RingRacers/src/p_map.c

// SONIC ROBO BLAST 2
//-----------------------------------------------------------------------------
// Copyright (C) 1993-1996 by id Software, Inc.
// Copyright (C) 1998-2000 by DooM Legacy Team.
// Copyright (C) 1999-2020 by Sonic Team Junior.
//
// This program is free software distributed under the
// terms of the GNU General Public License, version 2.
// See the 'LICENSE' file for more details.
//-----------------------------------------------------------------------------
/// \file  p_map.c
/// \brief Movement, collision handling
///
///	Shooting and aiming

#include "doomdef.h"
#include "g_game.h"
#include "m_bbox.h"
#include "m_random.h"
#include "p_local.h"
#include "p_setup.h" // NiGHTS stuff
#include "r_fps.h"
#include "r_state.h"
#include "r_main.h"
#include "r_sky.h"
#include "s_sound.h"
#include "w_wad.h"

#include "k_kart.h" // SRB2kart 011617
#include "k_collide.h"
#include "k_respawn.h"
#include "hu_stuff.h" // SRB2kart
#include "i_system.h" // SRB2kart
#include "k_terrain.h"
#include "k_objects.h"

#include "r_splats.h"

#include "p_slopes.h"

#include "z_zone.h"

#include "lua_hook.h"

#include "m_perfstats.h" // ps_checkposition_calls

tm_t tm = {0};

void P_RestoreTMStruct(tm_t tmrestore)
{
	// Reference count management
	if (tm.thing != tmrestore.thing)
	{
		P_SetTarget(&tm.thing, NULL);
	}

	if (tm.floorthing != tmrestore.floorthing)
	{
		P_SetTarget(&tm.floorthing, NULL);
	}

	if (tm.hitthing != tmrestore.hitthing)
	{
		P_SetTarget(&tm.hitthing, NULL);
	}

	// Restore state
	tm = tmrestore;

	// Validation
	if (tm.thing && P_MobjWasRemoved(tm.thing) == true)
	{
		P_SetTarget(&tm.thing, NULL);
	}

	if (tm.floorthing && P_MobjWasRemoved(tm.floorthing) == true)
	{
		P_SetTarget(&tm.floorthing, NULL);
	}

	if (tm.hitthing && P_MobjWasRemoved(tm.hitthing) == true)
	{
		P_SetTarget(&tm.hitthing, NULL);
	}
}


// Mostly re-ported from DOOM Legacy
// Keep track of special lines as they are hit, process them when the move is valid
static size_t *spechit = NULL;
static size_t spechit_max = 0U;
static size_t numspechit = 0U;

// Need a intermediate buffer for P_TryMove because it performs multiple moves
// the lines put into spechit will be moved into here after each checkposition,
// then and duplicates will be removed before processing
static size_t *spechitint = NULL;
static size_t spechitint_max = 0U;
static size_t numspechitint = 0U;


msecnode_t *sector_list = NULL;
mprecipsecnode_t *precipsector_list = NULL;
camera_t *mapcampointer;

//
// TELEPORT MOVE
//

//
// P_TeleportMove
//
static boolean P_TeleportMove(mobj_t *thing, fixed_t x, fixed_t y, fixed_t z)
{
	numspechit = 0U;

	// the move is ok,
	// so link the thing into its new position
	P_UnsetThingPosition(thing);

	// Remove touching_sectorlist from mobj.
	if (sector_list)
	{
		P_DelSeclist(sector_list);
		sector_list = NULL;
	}

	thing->x = x;
	thing->y = y;
	thing->z = z;

	P_SetThingPosition(thing);

	P_CheckPosition(thing, thing->x, thing->y, NULL);

	if (P_MobjWasRemoved(thing))
		return true;

	thing->floorz = tm.floorz;
	thing->ceilingz = tm.ceilingz;
	thing->floorrover = tm.floorrover;
	thing->ceilingrover = tm.ceilingrover;

	return true;
}

//
// P_SetOrigin - P_TeleportMove which RESETS interpolation values.
//
boolean P_SetOrigin(mobj_t *thing, fixed_t x, fixed_t y, fixed_t z)
{
	boolean result = P_TeleportMove(thing, x, y, z);

	if (result == true)
	{
		thing->old_x = thing->x;
		thing->old_y = thing->y;
		thing->old_z = thing->z;
	}

	return result;
}

//
// P_MoveOrigin - P_TeleportMove which KEEPS interpolation values.
//
boolean P_MoveOrigin(mobj_t *thing, fixed_t x, fixed_t y, fixed_t z)
{
	return P_TeleportMove(thing, x, y, z);
}

// =========================================================================
//                       MOVEMENT ITERATOR FUNCTIONS
// =========================================================================

// For our intermediate buffer, remove any duplicate entries by adding each one to
// a temprary buffer if it's not already in there, copy the temporary buffer back over the intermediate afterwards
static void spechitint_removedups(void)
{
	// Only needs to be run if there's more than 1 line crossed
	if (numspechitint > 1U)
	{
		boolean valueintemp = false;
		size_t i = 0U, j = 0U;
		size_t numspechittemp = 0U;
		size_t *spechittemp = Z_Calloc(numspechitint * sizeof(size_t), PU_STATIC, NULL);

		// Fill the hashtable
		for (i = 0U; i < numspechitint; i++)
		{
			valueintemp = false;
			for (j = 0; j < numspechittemp; j++)
			{
				if (spechitint[i] == spechittemp[j])
				{
					valueintemp = true;
					break;
				}
			}

			if (!valueintemp)
			{
				spechittemp[numspechittemp] = spechitint[i];
				numspechittemp++;
			}
		}

		// The hash table now IS the result we want to send back
		// easiest way to handle this is a memcpy
		if (numspechittemp != numspechitint)
		{
			memcpy(spechitint, spechittemp, numspechittemp * sizeof(size_t));
			numspechitint = numspechittemp;
		}

		Z_Free(spechittemp);
	}
}

// copy the contents of spechit into the end of spechitint
static void spechitint_copyinto(void)
{
	if (numspechit > 0U)
	{
		if (numspechitint + numspechit >= spechitint_max)
		{
			spechitint_max = spechitint_max + numspechit;
			spechitint = Z_Realloc(spechitint, spechitint_max * sizeof(size_t), PU_STATIC, NULL);
		}

		memcpy(&spechitint[numspechitint], spechit, numspechit * sizeof(size_t));
		numspechitint += numspechit;
	}
}

static void add_spechit(line_t *ld)
{
	if (numspechit >= spechit_max)
	{
		spechit_max = spechit_max ? spechit_max * 2U : 16U;
		spechit = Z_Realloc(spechit, spechit_max * sizeof(size_t), PU_STATIC, NULL);
	}

	spechit[numspechit] = ld - lines;
	numspechit++;
}

static boolean P_SpecialIsLinedefCrossType(line_t *ld)
{
	boolean linedefcrossspecial = false;

	// Take anything with any cross type for now,
	// we'll have to filter it down later...
	if (ld->activation & (SPAC_CROSS | SPAC_CROSSMONSTER | SPAC_CROSSMISSILE))
	{
		linedefcrossspecial = P_CanActivateSpecial(ld->special);
	}

	return linedefcrossspecial;
}

void
P_DoSpringEx
(		mobj_t * object,
		fixed_t scaleVal,
		fixed_t vertispeed,
		fixed_t horizspeed,
		angle_t finalAngle,
		UINT16 starcolor)
{
	if (object->eflags & MFE_SPRUNG)
	{
		// Object was already sprung this tic
		return;
	}

	if (horizspeed < 0)
	{
		horizspeed = -(horizspeed);
		finalAngle += ANGLE_180;
	}

	object->standingslope = NULL; // Okay, now we know it's not going to be relevant - no launching off at silly angles for you.
	object->terrain = NULL;

	object->eflags |= MFE_SPRUNG; // apply this flag asap!

	if ((vertispeed < 0) ^ P_IsObjectFlipped(object))
		vertispeed *= 2;

	if (vertispeed)
	{
		object->momz = FixedMul(vertispeed, scaleVal);
	}

	if (horizspeed)
	{
		fixed_t finalSpeed = FixedMul(horizspeed, scaleVal);
		fixed_t objectSpeed;

		if (object->player)
			objectSpeed = object->player->speed;
		else
			objectSpeed = R_PointToDist2(0, 0, object->momx, object->momy);

		if (!vertispeed)
		{
			// Scale to gamespeed
			finalSpeed = FixedMul(finalSpeed, K_GetKartGameSpeedScalar(gamespeed));

			// Reflect your momentum angle against the surface of horizontal springs.
			// This makes it a bit more interesting & unique than just being a speed boost in a pre-defined direction
			if (object->momx || object->momy)
			{
				finalAngle = K_ReflectAngle(
					R_PointToAngle2(0, 0, object->momx, object->momy), finalAngle,
					objectSpeed, finalSpeed
				);
			}
		}

		// Horizontal speed is used as a minimum thrust, not a direct replacement
		finalSpeed = max(objectSpeed, finalSpeed);

		P_InstaThrust(object, finalAngle, finalSpeed);
	}

	if (object->player)
	{
		K_TumbleInterrupt(object->player);
		P_ResetPlayer(object->player);

		object->player->springstars = max(abs(vertispeed), horizspeed) / FRACUNIT / 2;
		object->player->springcolor = starcolor;

		// Less friction when hitting springs
		if (!object->player->tiregrease)
		{
			UINT8 i;
			for (i = 0; i < 2; i++)
			{
				mobj_t *grease;
				grease = P_SpawnMobj(object->x, object->y, object->z, MT_TIREGREASE);
				P_SetTarget(&grease->target, object);
				grease->angle = K_MomentumAngle(object);
				grease->extravalue1 = i;
				K_ReduceVFX(grease, object->player);
			}
		}

		if (object->player->tiregrease < greasetics)
		{
			object->player->tiregrease = greasetics;
		}
	}
}

//
// P_DoSpring
//
// mass = vertical speed
// damage = horizontal speed
// raisestate = state to change spring to on collision
// painchance = star effect color
//
boolean P_DoSpring(mobj_t *spring, mobj_t *object)
{
	const fixed_t scaleVal = FixedSqrt(FixedMul(mapobjectscale, spring->scale));
	fixed_t vertispeed = spring->info->mass;
	fixed_t horizspeed = spring->info->damage;
	UINT16 starcolor = (spring->info->painchance % numskincolors);
	fixed_t savemomx = object->momx;
	fixed_t savemomy = object->momy;
	statenum_t raisestate = spring->info->raisestate;

	// Object was already sprung this tic
	if (object->eflags & MFE_SPRUNG)
		return false;

	// Spectators don't trigger springs.
	if (object->player && object->player->spectator)
		return false;

	// "Even in Death" is a song from Volume 8, not a command.
	if (!spring->health || !object->health)
		return false;

#if 0
	if (horizspeed && vertispeed) // Mimic SA
	{
		object->momx = object->momy = 0;
		P_TryMove(object, spring->x, spring->y, true, NULL);
	}
#endif

	// Does nothing?
	if (!vertispeed && !horizspeed)
	{
		return false;
	}

	spring->flags |= MF_NOCLIPTHING; // De-solidify

	if (spring->eflags & MFE_VERTICALFLIP)
		vertispeed *= -1;

	// Vertical springs teleport you on TOP of them.
	if (vertispeed > 0)
	{
		object->z = spring->z + spring->height + 1;
	}
	else if (vertispeed < 0)
	{
		object->z = spring->z - object->height - 1;
	}
	else
	{
		fixed_t offx, offy;

		// Horizontal springs teleport you in FRONT of them.
		savemomx = object->momx;
		savemomy = object->momy;
		object->momx = object->momy = 0;

		// Overestimate the distance to position you at
		offx = P_ReturnThrustX(spring, spring->angle, (spring->radius + object->radius + 1) * 2);
		offy = P_ReturnThrustY(spring, spring->angle, (spring->radius + object->radius + 1) * 2);

		// Then clip it down to a square, so it matches the hitbox size.
		if (offx > (spring->radius + object->radius + 1))
			offx = spring->radius + object->radius + 1;
		else if (offx < -(spring->radius + object->radius + 1))
			offx = -(spring->radius + object->radius + 1);

		P_TryMove(object, spring->x + offx, spring->y + offy, true, NULL);
	}

	object->momx = savemomx;
	object->momy = savemomy;

	P_DoSpringEx(object, scaleVal, vertispeed, horizspeed,
			spring->angle, starcolor);

	// Re-solidify
	spring->flags = (spring->flags & ~(MF_NOCLIPTHING)) | (spring->info->flags & (MF_NOCLIPTHING));

	if (object->player)
	{
		if (spring->flags & MF_ENEMY) // Spring shells
		{
			P_SetTarget(&spring->target, object);
		}

		if (spring->type == MT_POGOSPRING)
		{
			if (spring->reactiontime == 0)
			{
				object->player->tricktime = 0; // Reset post-hitlag timer
				// Setup the boost for potential upwards trick, at worse, make it your regular max speed. (boost = curr speed*1.25)
				object->player->trickboostpower = max(FixedDiv(object->player->speed, K_GetKartSpeed(object->player, false, false)) - FRACUNIT, 0)*125/100;
				//CONS_Printf("Got boost: %d%\n", mo->player->trickboostpower*100 / FRACUNIT);
				object->player->trickpanel = 1;
				object->player->pflags |= PF_TRICKDELAY;
			}
			else
			{
				raisestate = spring->info->seestate;

				object->player->tumbleBounces = 1;
				object->player->pflags &= ~PF_TUMBLESOUND;
				object->player->tumbleHeight = 50;
				P_SetPlayerMobjState(object->player->mo, S_KART_SPINOUT);

				// FIXME: try to compensate tumbling gravity
				object->momz = 3 * object->momz / 2;
			}

			spring->reactiontime++;
		}
	}

	P_SetMobjState(spring, raisestate);

	return true;
}

static void P_DoFanAndGasJet(mobj_t *spring, mobj_t *object)
{
	player_t *p = object->player; // will be NULL if not a player
	fixed_t zdist; // distance between bottoms
	fixed_t speed = spring->info->mass; // conveniently, both fans and gas jets use this for the vertical thrust
	SINT8 flipval = P_MobjFlip(spring); // virtually everything here centers around the thruster's gravity, not the object's!

	if (p && object->state == &states[object->info->painstate]) // can't use fans and gas jets when player is in pain!
		return;

	// is object's top below thruster's position? if not, calculate distance between their bottoms
	if (spring->eflags & MFE_VERTICALFLIP)
	{
		if (object->z > spring->z + spring->height)
			return;
		zdist = (spring->z + spring->height) - (object->z + object->height);
	}
	else
	{
		if (object->z + object->height < spring->z)
			return;
		zdist = object->z - spring->z;
	}

	object->standingslope = NULL; // No launching off at silly angles for you.
	object->terrain = NULL;

	switch (spring->type)
	{
		case MT_FAN: // fan
			if (zdist > (spring->health << FRACBITS)) // max z distance determined by health (set by map thing args[0])
				break;
			if (flipval*object->momz >= FixedMul(speed, spring->scale)) // if object's already moving faster than your best, don't bother
				break;

			object->momz += flipval*FixedMul(speed/4, spring->scale);

			// limit the speed if too high
			if (flipval*object->momz > FixedMul(speed, spring->scale))
				object->momz = flipval*FixedMul(speed, spring->scale);
			break;
		case MT_STEAM: // Steam
			if (zdist > FixedMul(16*FRACUNIT, spring->scale))
				break;
			if (spring->state != &states[S_STEAM1]) // Only when it bursts
				break;
			if (object->eflags & MFE_SPRUNG)
				break;

			if (spring->spawnpoint && spring->spawnpoint->args[1])
			{
				if (object->player)
				{
					object->player->trickpanel = 1;
					object->player->pflags |= PF_TRICKDELAY;
				}

				K_DoPogoSpring(object, 32<<FRACBITS, 0);
			}
			else
			{
				object->momz = flipval*FixedMul(speed, FixedSqrt(FixedMul(spring->scale, object->scale))); // scale the speed with both objects' scales, just like with springs!
			}

			object->eflags |= MFE_SPRUNG;
			break;
		default:
			break;
	}
}

//
// PIT_CheckThing
//
static BlockItReturn_t PIT_CheckThing(mobj_t *thing)
{
	fixed_t blockdist;

	if (tm.thing == NULL || P_MobjWasRemoved(tm.thing) == true)
		return BMIT_STOP; // func just popped our tm.thing, cannot continue.

	// Ignore... things.
	if (thing == NULL || P_MobjWasRemoved(thing) == true)
		return BMIT_CONTINUE;

	// don't clip against self
	if (thing == tm.thing)
		return BMIT_CONTINUE;

	// Ignore spectators
	if ((tm.thing->player && tm.thing->player->spectator)
	|| (thing->player && thing->player->spectator))
		return BMIT_CONTINUE;

	// Ignore the collision if BOTH things are in hitlag.
	if (thing->hitlag > 0 && tm.thing->hitlag > 0)
		return BMIT_CONTINUE;

	if ((thing->flags & MF_NOCLIPTHING) || !(thing->flags & (MF_SOLID|MF_SPECIAL|MF_PAIN|MF_SHOOTABLE|MF_SPRING)))
		return BMIT_CONTINUE;

	blockdist = thing->radius + tm.thing->radius;

	if (abs(thing->x - tm.x) >= blockdist || abs(thing->y - tm.y) >= blockdist)
		return BMIT_CONTINUE; // didn't hit it

	if (thing->flags & MF_PAPERCOLLISION) // CAUTION! Very easy to get stuck inside MF_SOLID objects. Giving the player MF_PAPERCOLLISION is a bad idea unless you know what you're doing.
	{
		fixed_t cosradius, sinradius;
		vertex_t v1, v2; // fake vertexes
		line_t junk; // fake linedef

		cosradius = FixedMul(thing->radius, FINECOSINE(thing->angle>>ANGLETOFINESHIFT));
		sinradius = FixedMul(thing->radius, FINESINE(thing->angle>>ANGLETOFINESHIFT));

		v1.x = thing->x - cosradius;
		v1.y = thing->y - sinradius;
		v2.x = thing->x + cosradius;
		v2.y = thing->y + sinradius;

		junk.v1 = &v1;
		junk.v2 = &v2;
		junk.dx = 2*cosradius; // v2.x - v1.x;
		junk.dy = 2*sinradius; // v2.y - v1.y;

		if (tm.thing->flags & MF_PAPERCOLLISION) // more strenuous checking to prevent clipping issues
		{
			INT32 check1, check2, check3, check4;
			fixed_t tmcosradius = FixedMul(tm.thing->radius, FINECOSINE(tm.thing->angle>>ANGLETOFINESHIFT));
			fixed_t tmsinradius = FixedMul(tm.thing->radius, FINESINE(tm.thing->angle>>ANGLETOFINESHIFT));
			if (abs(thing->x - tm.x) >= (abs(tmcosradius) + abs(cosradius)) || abs(thing->y - tm.y) >= (abs(tmsinradius) + abs(sinradius)))
				return BMIT_CONTINUE; // didn't hit it
			check1 = P_PointOnLineSide(tm.x - tmcosradius, tm.y - tmsinradius, &junk);
			check2 = P_PointOnLineSide(tm.x + tmcosradius, tm.y + tmsinradius, &junk);
			check3 = P_PointOnLineSide(tm.x + tm.thing->momx - tmcosradius, tm.y + tm.thing->momy - tmsinradius, &junk);
			check4 = P_PointOnLineSide(tm.x + tm.thing->momx + tmcosradius, tm.y + tm.thing->momy + tmsinradius, &junk);
			if ((check1 == check2) && (check2 == check3) && (check3 == check4))
				return BMIT_CONTINUE; // the line doesn't cross between collider's start or end
		}
		else
		{
			if (abs(thing->x - tm.x) >= (tm.thing->radius + abs(cosradius)) || abs(thing->y - tm.y) >= (tm.thing->radius + abs(sinradius)))
				return BMIT_CONTINUE; // didn't hit it
			if ((P_PointOnLineSide(tm.x - tm.thing->radius, tm.y - tm.thing->radius, &junk)
			== P_PointOnLineSide(tm.x + tm.thing->radius, tm.y + tm.thing->radius, &junk))
			&& (P_PointOnLineSide(tm.x + tm.thing->radius, tm.y - tm.thing->radius, &junk)
			== P_PointOnLineSide(tm.x - tm.thing->radius, tm.y + tm.thing->radius, &junk)))
				return BMIT_CONTINUE; // the line doesn't cross between either pair of opposite corners
		}
	}
	else if (tm.thing->flags & MF_PAPERCOLLISION)
	{
		fixed_t tmcosradius, tmsinradius;
		vertex_t v1, v2; // fake vertexes
		line_t junk; // fake linedef

		tmcosradius = FixedMul(tm.thing->radius, FINECOSINE(tm.thing->angle>>ANGLETOFINESHIFT));
		tmsinradius = FixedMul(tm.thing->radius, FINESINE(tm.thing->angle>>ANGLETOFINESHIFT));

		if (abs(thing->x - tm.x) >= (thing->radius + abs(tmcosradius)) || abs(thing->y - tm.y) >= (thing->radius + abs(tmsinradius)))
			return BMIT_CONTINUE; // didn't hit it

		v1.x = tm.x - tmcosradius;
		v1.y = tm.y - tmsinradius;
		v2.x = tm.x + tmcosradius;
		v2.y = tm.y + tmsinradius;

		junk.v1 = &v1;
		junk.v2 = &v2;
		junk.dx = 2*tmcosradius; // v2.x - v1.x;
		junk.dy = 2*tmsinradius; // v2.y - v1.y;

		// no need to check whether other thing has MF_PAPERCOLLISION, since would fall under other condition
		if ((P_PointOnLineSide(thing->x - thing->radius, thing->y - thing->radius, &junk)
		== P_PointOnLineSide(thing->x + thing->radius, thing->y + thing->radius, &junk))
		&& (P_PointOnLineSide(thing->x + thing->radius, thing->y - thing->radius, &junk)
		== P_PointOnLineSide(thing->x - thing->radius, thing->y + thing->radius, &junk)))
			return BMIT_CONTINUE; // the line doesn't cross between either pair of opposite corners
	}

	{
		UINT8 shouldCollide = LUA_Hook2Mobj(thing, tm.thing, MOBJ_HOOK(MobjCollide)); // checks hook for thing's type
		if (P_MobjWasRemoved(tm.thing) || P_MobjWasRemoved(thing))
			return BMIT_CONTINUE; // one of them was removed???
		if (shouldCollide == 1)
			return BMIT_ABORT; // force collide
		else if (shouldCollide == 2)
			return BMIT_CONTINUE; // force no collide

		shouldCollide = LUA_Hook2Mobj(tm.thing, thing, MOBJ_HOOK(MobjMoveCollide)); // checks hook for tm.thing's type
		if (P_MobjWasRemoved(tm.thing) || P_MobjWasRemoved(thing))
			return BMIT_CONTINUE; // one of them was removed???
		if (shouldCollide == 1)
			return BMIT_ABORT; // force collide
		else if (shouldCollide == 2)
			return BMIT_CONTINUE; // force no collide
	}

	// When solid spikes move, assume they just popped up and teleport things on top of them to hurt.
	if (tm.thing->type == MT_SPIKE && tm.thing->flags & MF_SOLID)
	{
		if (thing->z > tm.thing->z + tm.thing->height)
			return BMIT_CONTINUE; // overhead
		if (thing->z + thing->height < tm.thing->z)
			return BMIT_CONTINUE; // underneath

		if (tm.thing->eflags & MFE_VERTICALFLIP)
			P_SetOrigin(thing, thing->x, thing->y, tm.thing->z - thing->height - FixedMul(FRACUNIT, tm.thing->scale));
		else
			P_SetOrigin(thing, thing->x, thing->y, tm.thing->z + tm.thing->height + FixedMul(FRACUNIT, tm.thing->scale));
		if (thing->flags & MF_SHOOTABLE)
			P_DamageMobj(thing, tm.thing, tm.thing, 1, 0);
		return BMIT_CONTINUE;
	}

	if (thing->flags & MF_PAIN)
	{ // Player touches painful thing sitting on the floor
		// see if it went over / under
		if (thing->z > tm.thing->z + tm.thing->height)
			return BMIT_CONTINUE; // overhead
		if (thing->z + thing->height < tm.thing->z)
			return BMIT_CONTINUE; // underneath
		if (tm.thing->flags & MF_SHOOTABLE && thing->health > 0)
		{
			UINT32 damagetype = (thing->info->mass & 0xFF);

			if (P_DamageMobj(tm.thing, thing, thing, 1, damagetype) && (damagetype = (thing->info->mass>>8)))
				S_StartSound(thing, damagetype);
		}
		return BMIT_CONTINUE;
	}
	else if (tm.thing->flags & MF_PAIN && thing->player)
	{ // Painful thing splats player in the face
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath
		if (thing->flags & MF_SHOOTABLE && tm.thing->health > 0)
		{
			UINT32 damagetype = (tm.thing->info->mass & 0xFF);

			if (P_DamageMobj(thing, tm.thing, tm.thing, 1, damagetype) && (damagetype = (tm.thing->info->mass>>8)))
				S_StartSound(tm.thing, damagetype);
		}
		return BMIT_CONTINUE;
	}

	// check for skulls slamming into things
	if (tm.thing->flags2 & MF2_SKULLFLY)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		tm.thing->flags2 &= ~MF2_SKULLFLY;
		tm.thing->momx = tm.thing->momy = tm.thing->momz = 0;
		return BMIT_ABORT; // stop moving
	}

	// SRB2kart 011617 - Colission[sic] code for kart items //{

	if (thing->type == MT_SPB)
	{
		if (tm.thing->type != MT_PLAYER
			&& thing->tracer != tm.thing)
		{
			// Needs to be a player or the
			// thing that we're chasing.
			return BMIT_CONTINUE;
		}

		if (tm.thing->z > thing->z + thing->height)
		{
			return BMIT_CONTINUE; // overhead
		}

		if (tm.thing->z + tm.thing->height < thing->z)
		{
			return BMIT_CONTINUE; // underneath
		}

		Obj_SPBTouch(thing, tm.thing);
		return BMIT_CONTINUE;
	}
	else if (tm.thing->type == MT_SPB)
	{
		if (thing->type != MT_PLAYER
			&& tm.thing->tracer != thing)
		{
			// Needs to be a player or the
			// thing that we're chasing.
			return BMIT_CONTINUE;
		}

		if (tm.thing->z > thing->z + thing->height)
		{
			return BMIT_CONTINUE; // overhead
		}

		if (tm.thing->z + tm.thing->height < thing->z)
		{
			return BMIT_CONTINUE; // underneath
		}

		Obj_SPBTouch(tm.thing, thing);
		return BMIT_CONTINUE;
	}

	if (thing->type == MT_SHRINK_GUN || thing->type == MT_SHRINK_PARTICLE)
	{
		if (tm.thing->type != MT_PLAYER)
		{
			return BMIT_CONTINUE;
		}

		if (thing->type == MT_SHRINK_GUN)
		{
			// Use special collision for the laser gun.
			// The laser sprite itself is just a visual,
			// the gun itself does the colliding for us.
			if (tm.thing->z > thing->z)
			{
				return BMIT_CONTINUE; // overhead
			}

			if (tm.thing->z + tm.thing->height < thing->floorz)
			{
				return BMIT_CONTINUE; // underneath
			}
		}
		else
		{
			if (tm.thing->z > thing->z + thing->height)
			{
				return BMIT_CONTINUE; // overhead
			}

			if (tm.thing->z + tm.thing->height < thing->z)
			{
				return BMIT_CONTINUE; // underneath
			}
		}

		return Obj_ShrinkLaserCollide(thing, tm.thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}
	else if (tm.thing->type == MT_SHRINK_GUN || tm.thing->type == MT_SHRINK_PARTICLE)
	{
		if (thing->type != MT_PLAYER)
		{
			return BMIT_CONTINUE;
		}

		if (tm.thing->type == MT_SHRINK_GUN)
		{
			// Use special collision for the laser gun.
			// The laser sprite itself is just a visual,
			// the gun itself does the colliding for us.
			if (thing->z > tm.thing->z)
			{
				return BMIT_CONTINUE; // overhead
			}

			if (thing->z + thing->height < tm.thing->floorz)
			{
				return BMIT_CONTINUE; // underneath
			}
		}
		else
		{
			if (tm.thing->z > thing->z + thing->height)
			{
				return BMIT_CONTINUE; // overhead
			}

			if (tm.thing->z + tm.thing->height < thing->z)
			{
				return BMIT_CONTINUE; // underneath
			}
		}

		return Obj_ShrinkLaserCollide(tm.thing, thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}

	if (tm.thing->type == MT_SMK_ICEBLOCK)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_SMKIceBlockCollide(tm.thing, thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}
	else if (thing->type == MT_SMK_ICEBLOCK)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_SMKIceBlockCollide(thing, tm.thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}

	if (tm.thing->type == MT_EGGMANITEM || tm.thing->type == MT_EGGMANITEM_SHIELD)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_EggItemCollide(tm.thing, thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}
	else if (thing->type == MT_EGGMANITEM || thing->type == MT_EGGMANITEM_SHIELD)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_EggItemCollide(thing, tm.thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}

	if (tm.thing->type == MT_RANDOMITEM)
		return BMIT_CONTINUE;

	// Bubble Shield reflect
	if (((thing->type == MT_BUBBLESHIELD && thing->target->player && thing->target->player->bubbleblowup)
		|| (thing->player && thing->player->bubbleblowup))
		&& (tm.thing->type == MT_ORBINAUT || tm.thing->type == MT_JAWZ || tm.thing->type == MT_GACHABOM
		|| tm.thing->type == MT_BANANA || tm.thing->type == MT_EGGMANITEM || tm.thing->type == MT_BALLHOG
		|| tm.thing->type == MT_SSMINE || tm.thing->type == MT_LANDMINE || tm.thing->type == MT_SINK
		|| tm.thing->type == MT_GARDENTOP
		|| (tm.thing->type == MT_PLAYER && thing->target != tm.thing)))
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_BubbleShieldCollide(thing, tm.thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}
	else if (((tm.thing->type == MT_BUBBLESHIELD && tm.thing->target->player && tm.thing->target->player->bubbleblowup)
		|| (tm.thing->player && tm.thing->player->bubbleblowup))
		&& (thing->type == MT_ORBINAUT || thing->type == MT_JAWZ || thing->type == MT_GACHABOM
		|| thing->type == MT_BANANA || thing->type == MT_EGGMANITEM || thing->type == MT_BALLHOG
		|| thing->type == MT_SSMINE || tm.thing->type == MT_LANDMINE || thing->type == MT_SINK
		|| thing->type == MT_GARDENTOP
		|| (thing->type == MT_PLAYER && tm.thing->target != thing)))
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_BubbleShieldCollide(tm.thing, thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}

	// double make sure bubbles won't collide with anything else
	if (thing->type == MT_BUBBLESHIELD || tm.thing->type == MT_BUBBLESHIELD)
		return BMIT_CONTINUE;

	// Droptarget reflect
	if ((thing->type == MT_DROPTARGET || thing->type == MT_DROPTARGET_SHIELD)
		&& (tm.thing->type == MT_ORBINAUT || tm.thing->type == MT_JAWZ || tm.thing->type == MT_GACHABOM
		|| tm.thing->type == MT_BANANA || tm.thing->type == MT_EGGMANITEM || tm.thing->type == MT_BALLHOG
		|| tm.thing->type == MT_SSMINE || tm.thing->type == MT_LANDMINE || tm.thing->type == MT_SINK
		|| tm.thing->type == MT_GARDENTOP
		|| (tm.thing->type == MT_PLAYER)))
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_DropTargetCollide(thing, tm.thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}
	else if ((tm.thing->type == MT_DROPTARGET || tm.thing->type == MT_DROPTARGET_SHIELD)
		&& (thing->type == MT_ORBINAUT || thing->type == MT_JAWZ || thing->type == MT_GACHABOM
		|| thing->type == MT_BANANA || thing->type == MT_EGGMANITEM || thing->type == MT_BALLHOG
		|| thing->type == MT_SSMINE || tm.thing->type == MT_LANDMINE || thing->type == MT_SINK
		|| thing->type == MT_GARDENTOP
		|| (thing->type == MT_PLAYER)))
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_DropTargetCollide(tm.thing, thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}

	// double make sure drop targets won't collide with anything else
	if (thing->type == MT_DROPTARGET || tm.thing->type == MT_DROPTARGET
		|| thing->type == MT_DROPTARGET_SHIELD || tm.thing->type == MT_DROPTARGET_SHIELD)
		return BMIT_CONTINUE;

	if (tm.thing->type == MT_ORBINAUT || tm.thing->type == MT_JAWZ || tm.thing->type == MT_GACHABOM
		|| tm.thing->type == MT_ORBINAUT_SHIELD || tm.thing->type == MT_JAWZ_SHIELD
		|| tm.thing->type == MT_GARDENTOP)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return Obj_OrbinautJawzCollide(tm.thing, thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}
	else if (thing->type == MT_ORBINAUT || thing->type == MT_JAWZ || thing->type == MT_GACHABOM
		|| thing->type == MT_ORBINAUT_SHIELD || thing->type == MT_JAWZ_SHIELD
		|| thing->type == MT_GARDENTOP)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return Obj_OrbinautJawzCollide(thing, tm.thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}

	if (tm.thing->type == MT_BANANA || tm.thing->type == MT_BANANA_SHIELD || tm.thing->type == MT_BALLHOG)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_BananaBallhogCollide(tm.thing, thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}
	else if (thing->type == MT_BANANA || thing->type == MT_BANANA_SHIELD || thing->type == MT_BALLHOG)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_BananaBallhogCollide(thing, tm.thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}

	if (tm.thing->type == MT_SSMINE || tm.thing->type == MT_SSMINE_SHIELD)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_MineCollide(tm.thing, thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}
	else if (thing->type == MT_SSMINE || thing->type == MT_SSMINE_SHIELD)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_MineCollide(thing, tm.thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}

	if (tm.thing->type == MT_LANDMINE)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_LandMineCollide(tm.thing, thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}
	else if (thing->type == MT_LANDMINE)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_LandMineCollide(thing, tm.thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}

	if (tm.thing->type == MT_SINK)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_KitchenSinkCollide(tm.thing, thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}
	else if (thing->type == MT_SINK)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_KitchenSinkCollide(thing, tm.thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}

	if (tm.thing->type == MT_FALLINGROCK)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_FallingRockCollide(tm.thing, thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}
	else if (thing->type == MT_FALLINGROCK)
	{
		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		return K_FallingRockCollide(thing, tm.thing) ? BMIT_CONTINUE : BMIT_ABORT;
	}

	//}

	if ((thing->type == MT_SPRINGSHELL || thing->type == MT_YELLOWSHELL) && thing->health > 0
	 && (tm.thing->player || (tm.thing->flags & MF_PUSHABLE)) && tm.thing->health > 0)
	{
		// Multiplying by -1 inherently flips "less than" and "greater than"
		fixed_t tmz     = ((thing->eflags & MFE_VERTICALFLIP) ? -(tm.thing->z + tm.thing->height) : tm.thing->z);
		fixed_t tmznext = ((thing->eflags & MFE_VERTICALFLIP) ? -tm.thing->momz : tm.thing->momz) + tmz;
		fixed_t thzh    = ((thing->eflags & MFE_VERTICALFLIP) ? -thing->z : thing->z + thing->height);
		//fixed_t sprarea = FixedMul(8*FRACUNIT, thing->scale) * P_MobjFlip(thing);

		//if ((tmznext <= thzh && tmz > thzh) || (tmznext > thzh - sprarea && tmznext < thzh))
		if (tmznext <= thzh)
		{
			P_DoSpring(thing, tm.thing);
		//	return BMIT_CONTINUE;
		}
		//else if (tmz > thzh - sprarea && tmz < thzh) // Don't damage people springing up / down
			return BMIT_CONTINUE;
	}

	// missiles can hit other things
	if (tm.thing->flags & MF_MISSILE)
	{
		UINT8 damagetype = (tm.thing->info->mass ^ DMG_WOMBO);

		// see if it went over / under
		if (tm.thing->z > thing->z + thing->height)
			return BMIT_CONTINUE; // overhead
		if (tm.thing->z + tm.thing->height < thing->z)
			return BMIT_CONTINUE; // underneath

		if (tm.thing->target && tm.thing->target->type == thing->type)
		{
			// Don't hit same species as originator.
			if (thing == tm.thing->target)
				return BMIT_CONTINUE;

			if (thing->type != MT_PLAYER)
			{
				// Explode, but do no damage.
				// Let players missile other players.
				return BMIT_ABORT;
			}
		}

		if (!(thing->flags & MF_SHOOTABLE))
		{
			// didn't do any damage
			return (thing->flags & MF_SOLID) ? BMIT_ABORT : BMIT_CONTINUE;
		}

		// damage / explode
		P_DamageMobj(thing, tm.thing, tm.thing->target, 1, damagetype);

		// don't traverse any more
		return BMIT_ABORT;
	}

	if (thing->flags & MF_PUSHABLE && (tm.thing->player || tm.thing->flags & MF_PUSHABLE)
		&& tm.thing->z + tm.thing->height > thing->z && tm.thing->z < thing->z + thing->height
		&& !(netgame && tm.thing->player && tm.thing->player->spectator)) // Push thing!
	{
		if (thing->flags2 & MF2_SLIDEPUSH) // Make it slide
		{
			if (tm.thing->momy > 0 && tm.thing->momy > FixedMul(4*FRACUNIT, thing->scale) && tm.thing->momy > thing->momy)
			{
				thing->momy += FixedMul(PUSHACCEL, thing->scale);
				tm.thing->momy -= FixedMul(PUSHACCEL, thing->scale);
			}
			else if (tm.thing->momy < 0 && tm.thing->momy < FixedMul(-4*FRACUNIT, thing->scale)
				&& tm.thing->momy < thing->momy)
			{
				thing->momy -= FixedMul(PUSHACCEL, thing->scale);
				tm.thing->momy += FixedMul(PUSHACCEL, thing->scale);
			}
			if (tm.thing->momx > 0 && tm.thing->momx > FixedMul(4*FRACUNIT, thing->scale)
				&& tm.thing->momx > thing->momx)
			{
				thing->momx += FixedMul(PUSHACCEL, thing->scale);
				tm.thing->momx -= FixedMul(PUSHACCEL, thing->scale);
			}
			else if (tm.thing->momx < 0 && tm.thing->momx < FixedMul(-4*FRACUNIT, thing->scale)
				&& tm.thing->momx < thing->momx)
			{
				thing->momx -= FixedMul(PUSHACCEL, thing->scale);
				tm.thing->momx += FixedMul(PUSHACCEL, thing->scale);
			}

			if (thing->momx > FixedMul(thing->info->speed, thing->scale))
				thing->momx = FixedMul(thing->info->speed, thing->scale);
			else if (thing->momx < -FixedMul(thing->info->speed, thing->scale))
				thing->momx = -FixedMul(thing->info->speed, thing->scale);
			if (thing->momy > FixedMul(thing->info->speed, thing->scale))
				thing->momy = FixedMul(thing->info->speed, thing->scale);
			else if (thing->momy < -FixedMul(thing->info->speed, thing->scale))
				thing->momy = -FixedMul(thing->info->speed, thing->scale);
		}
		else
		{
			if (tm.thing->momx > FixedMul(4*FRACUNIT, thing->scale))
				tm.thing->momx = FixedMul(4*FRACUNIT, thing->scale);
			else if (tm.thing->momx < FixedMul(-4*FRACUNIT, thing->scale))
				tm.thing->momx = FixedMul(-4*FRACUNIT, thing->scale);
			if (tm.thing->momy > FixedMul(4*FRACUNIT, thing->scale))
				tm.thing->momy = FixedMul(4*FRACUNIT, thing->scale);
			else if (tm.thing->momy < FixedMul(-4*FRACUNIT, thing->scale))
				tm.thing->momy = FixedMul(-4*FRACUNIT, thing->scale);

			thing->momx = tm.thing->momx;
			thing->momy = tm.thing->momy;
		}

		if (thing->type != MT_GARGOYLE || P_IsObjectOnGround(thing))
			S_StartSound(thing, thing->info->activesound);

		P_SetTarget(&thing->target, tm.thing);
	}

	// check for special pickup
	if (thing->flags & MF_SPECIAL && tm.thing->player)
	{
		P_TouchSpecialThing(thing, tm.thing, true); // can remove thing
		return BMIT_CONTINUE;
	}
	// check again for special pickup
	if (tm.thing->flags & MF_SPECIAL && thing->player)
	{
		P_TouchSpecialThing(tm.thing, thing, true); // can remove thing
		return BMIT_CONTINUE;
	}

	// Sprite Spikes!
	// Do not return because solidity code comes below.
	if (tm.thing->type == MT_SPIKE && tm.thing->flags & MF_SOLID && thing->player) // moving spike rams into player?!
	{
		if (tm.thing->eflags & MFE_VERTICALFLIP)
		{
			if (thing->z + thing->height <= tm.thing->z + FixedMul(FRACUNIT, tm.thing->scale)
			&& thing->z + thing->height + thing->momz  >= tm.thing->z + FixedMul(FRACUNIT, tm.thing->scale) + tm.thing->momz)
				P_DamageMobj(thing, tm.thing, tm.thing, 1, DMG_NORMAL);
		}
		else if (thing->z >= tm.thing->z + tm.thing->height - FixedMul(FRACUNIT, tm.thing->scale)
		&& thing->z + thing->momz <= tm.thing->z + tm.thing->height - FixedMul(FRACUNIT, tm.thing->scale) + tm.thing->momz)
			P_DamageMobj(thing, tm.thing, tm.thing, 1, DMG_NORMAL);
	}
	else if (thing->type == MT_SPIKE && thing->flags & MF_SOLID && tm.thing->player) // unfortunate player falls into spike?!
	{
		if (thing->eflags & MFE_VERTICALFLIP)
		{
			if (tm.thing->z + tm.thing->height <= thing->z - FixedMul(FRACUNIT, thing->scale)
			&& tm.thing->z + tm.thing->height + tm.thing->momz >= thing->z - FixedMul(FRACUNIT, thing->scale))
				P_DamageMobj(tm.thing, thing, thing, 1, DMG_NORMAL);
		}
		else if (tm.thing->z >= thing->z + thing->height + FixedMul(FRACUNIT, thing->scale)
		&& tm.thing->z + tm.thing->momz <= thing->z + thing->height + FixedMul(FRACUNIT, thing->scale))
			P_DamageMobj(tm.thing, thing, thing, 1, DMG_NORMAL);
	}

	if (tm.thing->type == MT_WALLSPIKE && tm.thing->flags & MF_SOLID && thing->player) // wall spike impales player
	{
		fixed_t bottomz, topz;
		bottomz = tm.thing->z;
		topz = tm.thing->z + tm.thing->height;
		if (tm.thing->eflags & MFE_VERTICALFLIP)
			bottomz -= FixedMul(FRACUNIT, tm.thing->scale);
		else
			topz += FixedMul(FRACUNIT, tm.thing->scale);

		if (thing->z + thing->height > bottomz // above bottom
		&&  thing->z < topz) // below top
		// don't check angle, the player was clearly in the way in this case
			P_DamageMobj(thing, tm.thing, tm.thing, 1, DMG_NORMAL);
	}
	else if (thing->type == MT_WALLSPIKE && thing->flags & MF_SOLID && tm.thing->player)
	{
		fixed_t bottomz, topz;
		angle_t touchangle = R_PointToAngle2(thing->tracer->x, thing->tracer->y, tm.thing->x, tm.thing->y);

		if (P_PlayerInPain(tm.thing->player) && (tm.thing->momx || tm.thing->momy))
		{
			angle_t playerangle = R_PointToAngle2(0, 0, tm.thing->momx, tm.thing->momy) - touchangle;
			if (playerangle > ANGLE_180)
				playerangle = InvAngle(playerangle);
			if (playerangle < ANGLE_90)
				return BMIT_CONTINUE; // Yes, this is intentionally outside the z-height check. No standing on spikes whilst moving away from them.
		}

		bottomz = thing->z;
		topz = thing->z + thing->height;

		if (thing->eflags & MFE_VERTICALFLIP)
			bottomz -= FixedMul(FRACUNIT, thing->scale);
		else
			topz += FixedMul(FRACUNIT, thing->scale);

		if (tm.thing->z + tm.thing->height > bottomz // above bottom
		&&  tm.thing->z < topz // below top
		&& !P_MobjWasRemoved(thing->tracer)) // this probably wouldn't work if we didn't have a tracer
		{ // use base as a reference point to determine what angle you touched the spike at
			touchangle = thing->angle - touchangle;
			if (touchangle > ANGLE_180)
				touchangle = InvAngle(touchangle);
			if (touchangle <= ANGLE_22h) // if you touched it at this close an angle, you get poked!
				P_DamageMobj(tm.thing, thing, thing, 1, DMG_NORMAL);
		}
	}

	if (thing->flags & MF_PUSHABLE)
	{
		if (tm.thing->type == MT_FAN || tm.thing->type == MT_STEAM)
			P_DoFanAndGasJet(tm.thing, thing);
	}

	if (tm.thing->flags & MF_PUSHABLE)
	{
		if (thing->type == MT_FAN || thing->type == MT_STEAM)
		{
			P_DoFanAndGasJet(thing, tm.thing);
			return BMIT_CONTINUE;
		}
		else if (thing->flags & MF_SPRING)
		{
			if ( thing->z <= tm.thing->z + tm.thing->height
			&& tm.thing->z <= thing->z + thing->height)
				if (P_DoSpring(thing, tm.thing))
					return BMIT_ABORT;
			return BMIT_CONTINUE;
		}
	}

	// thanks to sal for solidenemies dot lua
	if (thing->flags & (MF_ENEMY|MF_BOSS) && tm.thing->flags & (MF_ENEMY|MF_BOSS))
	{
		if ((thing->z + thing->height >= tm.thing->z)
		&& (tm.thing->z + tm.thing->height >= thing->z))
			return BMIT_ABORT;
	}

	if (thing->player)
	{
		if (tm.thing->type == MT_FAN || tm.thing->type == MT_STEAM)
			P_DoFanAndGasJet(tm.thing, thing);
	}

	if (tm.thing->player) // Is the moving/interacting object the player?
	{
		if (!tm.thing->health)
			return BMIT_CONTINUE;

		if (thing->type == MT_FAN || thing->type == MT_STEAM)
			P_DoFanAndGasJet(thing, tm.thing);
		else if (thing->flags & MF_SPRING)
		{
			if ( thing->z <= tm.thing->z + tm.thing->height
			&& tm.thing->z <= thing->z + thing->height)
				if (P_DoSpring(thing, tm.thing))
					return BMIT_ABORT;
			return BMIT_CONTINUE;
		}
		else if (thing->player) // bounce when players collide
		{
			// see if it went over / under
			if (tm.thing->z > thing->z + thing->height)
				return BMIT_CONTINUE; // overhead
			if (tm.thing->z + tm.thing->height < thing->z)
				return BMIT_CONTINUE; // underneath

			if (thing->player->hyudorotimer || tm.thing->player->hyudorotimer)
			{
				return BMIT_CONTINUE;
			}

			if ((gametyperules & GTR_BUMPERS)
				&& ((thing->player->bumpers && !tm.thing->player->bumpers)
				|| (tm.thing->player->bumpers && !thing->player->bumpers)))
			{
				return BMIT_CONTINUE;
			}

			// The bump has to happen last
			if (P_IsObjectOnGround(thing) && tm.thing->momz < 0 && tm.thing->player->trickpanel)
			{
				P_DamageMobj(thing, tm.thing, tm.thing, 1, DMG_WIPEOUT|DMG_STEAL);
			}
			else if (P_IsObjectOnGround(tm.thing) && thing->momz < 0 && thing->player->trickpanel)
			{
				P_DamageMobj(tm.thing, thing, thing, 1, DMG_WIPEOUT|DMG_STEAL);
			}

			if (K_KartBouncing(tm.thing, thing) == true)
			{
				K_PvPTouchDamage(tm.thing, thing);
			}

			return BMIT_CONTINUE;
		}
		else if (thing->type == MT_SPECIAL_UFO)
		{
			if (!(thing->flags & MF_SPECIAL))
			{
				Obj_PlayerUFOCollide(thing, tm.thing);
				return BMIT_CONTINUE;
			}
		}
		else if (thing->type == MT_BLUEROBRA_HEAD || thing->type == MT_BLUEROBRA_JOINT)
		{
			// see if it went over / under
			if (tm.thing->z > thing->z + thing->height)
				return BMIT_CONTINUE; // overhead
			if (tm.thing->z + tm.thing->height < thing->z)
				return BMIT_CONTINUE; // underneath

			if (!thing->health)
				return BMIT_CONTINUE; // dead

			if (tm.thing->player->invincibilitytimer > 0
				|| K_IsBigger(tm.thing, thing) == true)
			{
				if (thing->type == MT_BLUEROBRA_JOINT)
					P_KillMobj(thing->target, tm.thing, tm.thing, DMG_NORMAL);
				else
					P_KillMobj(thing, tm.thing, tm.thing, DMG_NORMAL);
				return BMIT_CONTINUE;
			}
			else
			{
				K_KartSolidBounce(tm.thing, thing);
				return BMIT_CONTINUE;
			}
		}
		else if (thing->type == MT_SMK_PIPE)
		{
			// see if it went over / under
			if (tm.thing->z > thing->z + thing->height)
				return BMIT_CONTINUE; // overhead
			if (tm.thing->z + tm.thing->height < thing->z)
				return BMIT_CONTINUE; // underneath

			if (!thing->health)
				return BMIT_CONTINUE; // dead

			if (tm.thing->player->invincibilitytimer > 0
				|| K_IsBigger(tm.thing, thing) == true)
			{
				P_KillMobj(thing, tm.thing, tm.thing, DMG_NORMAL);
				return BMIT_CONTINUE; // kill
			}

			K_KartSolidBounce(tm.thing, thing);
			return BMIT_CONTINUE;
		}
		else if (thing->type == MT_SMK_THWOMP)
		{
			if (!thing->health)
				return BMIT_CONTINUE; // dead

			if (!thwompsactive)
				return BMIT_CONTINUE; // not active yet

			if ((tm.thing->z < thing->z) && (thing->z >= thing->movefactor-(256<<FRACBITS)))
			{
				thing->extravalue1 = 1; // purposely try to stomp on players early
				//S_StartSound(thing, sfx_s1bb);
			}

			// see if it went over / under
			if (tm.thing->z > thing->z + thing->height)
				return BMIT_CONTINUE; // overhead
			if (tm.thing->z + tm.thing->height < thing->z)
				return BMIT_CONTINUE; // underneath

			// kill
			if (tm.thing->player->invincibilitytimer > 0
				|| K_IsBigger(tm.thing, thing) == true)
			{
				P_KillMobj(thing, tm.thing, tm.thing, DMG_NORMAL);
				return BMIT_CONTINUE;
			}

			// no interaction
			if (tm.thing->player->flashing > 0 || tm.thing->player->hyudorotimer > 0 || tm.thing->player->spinouttimer > 0)
				return BMIT_CONTINUE;

			// collide
			if (tm.thing->z < thing->z && thing->momz < 0)
				P_DamageMobj(tm.thing, thing, thing, 1, DMG_TUMBLE);
			else
			{
				if ((K_KartSolidBounce(tm.thing, thing) == true) && (thing->flags2 & MF2_AMBUSH))
				{
					P_DamageMobj(tm.thing, thing, thing, 1, DMG_WIPEOUT);
				}
			}

			return BMIT_CONTINUE;
		}
		else if (thing->type == MT_KART_LEFTOVER)
		{
			// see if it went over / under
			if (tm.thing->z > thing->z + thing->height)
				return BMIT_CONTINUE; // overhead
			if (tm.thing->z + tm.thing->height < thing->z)
				return BMIT_CONTINUE; // underneath

			K_KartBouncing(tm.thing, thing);
			return BMIT_CONTINUE;
		}
		else if (thing->type == MT_MONITOR)
		{
			// see if it went over / under
			if (tm.thing->z > thing->z + thing->height)
				return BMIT_CONTINUE; // overhead
			if (tm.thing->z + tm.thing->height < thing->z)
				return BMIT_CONTINUE; // underneath

			P_DamageMobj(thing, tm.thing, tm.thing, 1, DMG_NORMAL);
			K_KartBouncing(tm.thing, thing);
			return BMIT_CONTINUE;
		}
		else if (thing->flags & MF_SOLID)
		{
			// see if it went over / under
			if (tm.thing->z > thing->z + thing->height)
				return BMIT_CONTINUE; // overhead
			if (tm.thing->z + tm.thing->height < thing->z)
				return BMIT_CONTINUE; // underneath

			K_KartSolidBounce(tm.thing, thing);
			return BMIT_CONTINUE;
		}
	}

	// This code is causing conflicts for Ring Racers,
	// as solid objects cause bumping. If you need to
	// bring back this code for a moving platform-style
	// object, separate it properly.
#if 0
	if ((tm.thing->flags & MF_SPRING || tm.thing->type == MT_STEAM || tm.thing->type == MT_SPIKE || tm.thing->type == MT_WALLSPIKE) && (thing->player))
		; // springs, gas jets and springs should never be able to step up onto a player
	// z checking at last
	// Treat noclip things as non-solid!
	else if ((thing->flags & (MF_SOLID|MF_NOCLIP)) == MF_SOLID
		&& (tm.thing->flags & (MF_SOLID|MF_NOCLIP)) == MF_SOLID)
	{
		fixed_t topz, tmtopz;

		if (tm.thing->eflags & MFE_VERTICALFLIP)
		{
			// pass under
			tmtopz = tm.thing->z;

			if (tmtopz > thing->z + thing->height)
			{
				if (thing->z + thing->height > tm.floorz)
				{
					tm.floorz = thing->z + thing->height;
					tm.floorrover = NULL;
					tm.floorslope = NULL;
					tm.floorpic = -1;
				}
				return BMIT_CONTINUE;
			}

			topz = thing->z - thing->scale; // FixedMul(FRACUNIT, thing->scale), but thing->scale == FRACUNIT in base scale anyways

			// block only when jumping not high enough,
			// (dont climb max. 24units while already in air)
			// since return false doesn't handle momentum properly,
			// we lie to P_TryMove() so it's always too high
			if (tm.thing->player && tm.thing->z + tm.thing->height > topz
				&& tm.thing->z + tm.thing->height < tm.thing->ceilingz)
			{
				if (thing->flags & MF_GRENADEBOUNCE && (thing->flags & MF_MONITOR || thing->info->flags & MF_MONITOR)) // Gold monitor hack...
					return BMIT_ABORT;

				tm.floorz = tm.ceilingz = topz; // block while in air
				tm.ceilingrover = NULL;
				tm.ceilingslope = NULL;
				tm.ceilingpic = -1;
				P_SetTarget(&tm.floorthing, thing); // needed for side collision
			}
			else if (topz < tm.ceilingz && tm.thing->z <= thing->z+thing->height)
			{
				tm.ceilingz = topz;
				tm.ceilingrover = NULL;
				tm.ceilingslope = NULL;
				tm.ceilingpic = -1;
				P_SetTarget(&tm.floorthing, thing); // thing we may stand on
			}
		}
		else
		{
			// pass under
			tmtopz = tm.thing->z + tm.thing->height;

			if (tmtopz < thing->z)
			{
				if (thing->z < tm.ceilingz)
				{
					tm.ceilingz = thing->z;
					tm.ceilingrover = NULL;
					tm.ceilingslope = NULL;
					tm.ceilingpic = -1;
				}
				return BMIT_CONTINUE;
			}

			topz = thing->z + thing->height + thing->scale; // FixedMul(FRACUNIT, thing->scale), but thing->scale == FRACUNIT in base scale anyways

			// block only when jumping not high enough,
			// (dont climb max. 24units while already in air)
			// since return false doesn't handle momentum properly,
			// we lie to P_TryMove() so it's always too high
			if (tm.thing->player && tm.thing->z < topz
				&& tm.thing->z > tm.thing->floorz)
			{
				if (thing->flags & MF_GRENADEBOUNCE && (thing->flags & MF_MONITOR || thing->info->flags & MF_MONITOR)) // Gold monitor hack...
					return BMIT_ABORT;

				tm.floorz = tm.ceilingz = topz; // block while in air
				tm.floorrover = NULL;
				tm.floorslope = NULL;
				tm.floorpic = -1;
				P_SetTarget(&tm.floorthing, thing); // needed for side collision
			}
			else if (topz > tm.floorz && tm.thing->z+tm.thing->height >= thing->z)
			{
				tm.floorz = topz;
				tm.floorrover = NULL;
				tm.floorslope = NULL;
				tm.floorpic = -1;
				P_SetTarget(&tm.floorthing, thing); // thing we may stand on
			}
		}
	}
#endif

	// not solid not blocked
	return BMIT_CONTINUE;
}

// PIT_CheckCameraLine
// Adjusts tm.floorz and tm.ceilingz as lines are contacted - FOR CAMERA ONLY
static BlockItReturn_t PIT_CheckCameraLine(line_t *ld)
{
	if (ld->polyobj && !(ld->polyobj->flags & POF_SOLID))
		return BMIT_CONTINUE;

	if (tm.bbox[BOXRIGHT] <= ld->bbox[BOXLEFT] || tm.bbox[BOXLEFT] >= ld->bbox[BOXRIGHT]
		|| tm.bbox[BOXTOP] <= ld->bbox[BOXBOTTOM] || tm.bbox[BOXBOTTOM] >= ld->bbox[BOXTOP])
	{
		return BMIT_CONTINUE;
	}

	if (P_BoxOnLineSide(tm.bbox, ld) != -1)
		return BMIT_CONTINUE;

	// A line has been hit

	// The moving thing's destination position will cross
	// the given line.
	// If this should not be allowed, return false.
	// If the line is special, keep track of it
	// to process later if the move is proven ok.
	// NOTE: specials are NOT sorted by order,
	// so two special lines that are only 8 pixels apart
	// could be crossed in either order.

	// this line is out of the if so upper and lower textures can be hit by a splat
	tm.blockingline = ld;
	if (!ld->backsector) // one sided line
	{
		if (P_PointOnLineSide(mapcampointer->x, mapcampointer->y, ld))
			return BMIT_CONTINUE; // don't hit the back side
		return BMIT_ABORT;
	}

	// set openrange, opentop, openbottom
	P_CameraLineOpening(ld);

	// adjust floor / ceiling heights
	if (opentop < tm.ceilingz)
	{
		tm.ceilingz = opentop;
		tm.ceilingline = ld;
	}

	if (openbottom > tm.floorz)
	{
		tm.floorz = openbottom;
	}

	if (highceiling > tm.drpoffceilz)
		tm.drpoffceilz = highceiling;

	if (lowfloor < tm.dropoffz)
		tm.dropoffz = lowfloor;

	return BMIT_CONTINUE;
}

boolean P_IsLineBlocking(const line_t *ld, const mobj_t *thing)
{
	// missiles can cross uncrossable lines
	if ((thing->flags & MF_MISSILE))
	{
		return false;
	}
	else
	{
		if (thing->player && thing->player->spectator)
		{
			// Allow spectators thru blocking lines.
			return false;
		}

		if (ld->flags & ML_IMPASSABLE)
		{
			// block objects from moving through this linedef.
			return true;
		}

		if (thing->player)
		{
			return (ld->flags & ML_BLOCKPLAYERS);
		}
		else if (thing->flags & (MF_ENEMY|MF_BOSS))
		{
			return (ld->flags & ML_BLOCKMONSTERS);
		}
	}

	return false;
}

boolean P_IsLineTripWire(const line_t *ld)
{
	return ld->tripwire;
}

//
// PIT_CheckLine
// Adjusts tm.floorz and tm.ceilingz as lines are contacted
//
static BlockItReturn_t PIT_CheckLine(line_t *ld)
{
	const fixed_t thingtop = tm.thing->z + tm.thing->height;

	if (ld->polyobj && !(ld->polyobj->flags & POF_SOLID))
		return BMIT_CONTINUE;

	if (tm.bbox[BOXRIGHT] <= ld->bbox[BOXLEFT] || tm.bbox[BOXLEFT] >= ld->bbox[BOXRIGHT]
	|| tm.bbox[BOXTOP] <= ld->bbox[BOXBOTTOM] || tm.bbox[BOXBOTTOM] >= ld->bbox[BOXTOP])
		return BMIT_CONTINUE;

	if (P_BoxOnLineSide(tm.bbox, ld) != -1)
		return BMIT_CONTINUE;

	if (tm.thing->flags & MF_PAPERCOLLISION) // Caution! Turning whilst up against a wall will get you stuck. You probably shouldn't give the player this flag.
	{
		fixed_t cosradius, sinradius;
		cosradius = FixedMul(tm.thing->radius, FINECOSINE(tm.thing->angle>>ANGLETOFINESHIFT));
		sinradius = FixedMul(tm.thing->radius, FINESINE(tm.thing->angle>>ANGLETOFINESHIFT));
		if (P_PointOnLineSide(tm.x - cosradius, tm.y - sinradius, ld)
		== P_PointOnLineSide(tm.x + cosradius, tm.y + sinradius, ld))
			return BMIT_CONTINUE; // the line doesn't cross between collider's start or end
#ifdef PAPER_COLLISIONCORRECTION
		{
			fixed_t dist;
			vertex_t result;
			angle_t langle;
			P_ClosestPointOnLine(tm.x, tm.y, ld, &result);
			langle = R_PointToAngle2(ld->v1->x, ld->v1->y, ld->v2->x, ld->v2->y);
			langle += ANGLE_90*(P_PointOnLineSide(tm.x, tm.y, ld) ? -1 : 1);
			dist = abs(FixedMul(tm.thing->radius, FINECOSINE((tm.thing->angle - langle)>>ANGLETOFINESHIFT)));
			cosradius = FixedMul(dist, FINECOSINE(langle>>ANGLETOFINESHIFT));
			sinradius = FixedMul(dist, FINESINE(langle>>ANGLETOFINESHIFT));
			tm.thing->flags |= MF_NOCLIP;
			P_MoveOrigin(tm.thing, result.x + cosradius - tm.thing->momx, result.y + sinradius - tm.thing->momy, tm.thing->z);
			tm.thing->flags &= ~MF_NOCLIP;
		}
#endif
	}

	// A line has been hit

	// The moving thing's destination position will cross
	// the given line.
	// If this should not be allowed, return false.
	// If the line is special, keep track of it
	// to process later if the move is proven ok.
	// NOTE: specials are NOT sorted by order,
	// so two special lines that are only 8 pixels apart
	// could be crossed in either order.

	// this line is out of the if so upper and lower textures can be hit by a splat
	tm.blockingline = ld;

	{
		UINT8 shouldCollide = LUA_HookMobjLineCollide(tm.thing, tm.blockingline); // checks hook for thing's type
		if (P_MobjWasRemoved(tm.thing))
			return BMIT_CONTINUE; // one of them was removed???
		if (shouldCollide == 1)
			return BMIT_ABORT; // force collide
		else if (shouldCollide == 2)
			return BMIT_CONTINUE; // force no collide
	}

	if (!ld->backsector) // one sided line
	{
		if (P_PointOnLineSide(tm.thing->x, tm.thing->y, ld))
			return BMIT_CONTINUE; // don't hit the back side
		return BMIT_ABORT;
	}

	if (P_IsLineBlocking(ld, tm.thing))
		return BMIT_ABORT;

	// set openrange, opentop, openbottom
	P_LineOpening(ld, tm.thing);

	// adjust floor / ceiling heights
	if (opentop < tm.ceilingz)
	{
		tm.ceilingz = opentop;
		tm.ceilingline = ld;
		tm.ceilingrover = openceilingrover;
		tm.ceilingslope = opentopslope;
		tm.ceilingpic = opentoppic;
		tm.ceilingstep = openceilingstep;
		if (thingtop == tm.thing->ceilingz)
		{
			tm.thing->ceilingdrop = openceilingdrop;
		}
	}

	if (openbottom > tm.floorz)
	{
		tm.floorz = openbottom;
		tm.floorrover = openfloorrover;
		tm.floorslope = openbottomslope;
		tm.floorpic = openbottompic;
		tm.floorstep = openfloorstep;
		if (tm.thing->z == tm.thing->floorz)
		{
			tm.thing->floordrop = openfloordrop;
		}
	}

	if (highceiling > tm.drpoffceilz)
		tm.drpoffceilz = highceiling;

	if (lowfloor < tm.dropoffz)
		tm.dropoffz = lowfloor;

	// we've crossed the line
	if (P_SpecialIsLinedefCrossType(ld))
	{
		add_spechit(ld);
	}
	else if (P_IsLineTripWire(ld))
	{
		fixed_t textop, texbottom;

		P_GetMidtextureTopBottom(ld, tm.x, tm.y,
				&textop, &texbottom);

		/* The effect handling is done later but it won't
			know the height values anymore. So don't even add
			this line to the list unless this thing clips the
			tripwire's midtexture. */
		if (tm.thing->z <= textop && thingtop >= texbottom)
			add_spechit(ld);
	}

	return BMIT_CONTINUE;
}

// =========================================================================
//                         MOVEMENT CLIPPING
// =========================================================================

//
// P_CheckPosition
// This is purely informative, nothing is modified
// (except things picked up).
//
// in:
//  a mobj_t (can be valid or invalid)
//  a position to be checked
//   (doesn't need to be related to the mobj_t->x,y)
//
// during:
//  special things are touched if MF_PICKUP
//  early out on solid lines?
//
// out:
//  newsubsec
//  tm.floorz
//  tm.ceilingz
//  tm.dropoffz
//  tm.drpoffceilz
//   the lowest point contacted
//   (monsters won't move to a dropoff)
//  speciallines[]
//  numspeciallines
//

// tm.floorz
//     the nearest floor or thing's top under tm.thing
// tm.ceilingz
//     the nearest ceiling or thing's bottom over tm.thing
//
boolean P_CheckPosition(mobj_t *thing, fixed_t x, fixed_t y, TryMoveResult_t *result)
{
	INT32 thingtop = thing->z + thing->height;
	INT32 xl, xh, yl, yh, bx, by;
	subsector_t *newsubsec;
	boolean blockval = true;

	ps_checkposition_calls++;

	I_Assert(thing != NULL);
#ifdef PARANOIA
	if (P_MobjWasRemoved(thing))
		I_Error("Previously-removed Thing of type %u crashes P_CheckPosition!", thing->type);
#endif

	P_SetTarget(&tm.thing, thing);
	tm.flags = thing->flags;

	tm.x = x;
	tm.y = y;

	tm.bbox[BOXTOP] = y + tm.thing->radius;
	tm.bbox[BOXBOTTOM] = y - tm.thing->radius;
	tm.bbox[BOXRIGHT] = x + tm.thing->radius;
	tm.bbox[BOXLEFT] = x - tm.thing->radius;

	newsubsec = R_PointInSubsector(x, y);
	tm.ceilingline = tm.blockingline = NULL;

	// The base floor / ceiling is from the subsector
	// that contains the point.
	// Any contacted lines the step closer together
	// will adjust them.
	tm.floorz = tm.dropoffz = P_GetFloorZ(thing, newsubsec->sector, x, y, NULL); //newsubsec->sector->floorheight;
	tm.ceilingz = P_GetCeilingZ(thing, newsubsec->sector, x, y, NULL); //newsubsec->sector->ceilingheight;
	tm.floorrover = NULL;
	tm.ceilingrover = NULL;
	tm.floorslope = newsubsec->sector->f_slope;
	tm.ceilingslope = newsubsec->sector->c_slope;
	tm.floorpic = newsubsec->sector->floorpic;
	tm.ceilingpic = newsubsec->sector->ceilingpic;

	tm.floorstep = 0;
	tm.ceilingstep = 0;

	if (thingtop < thing->ceilingz)
	{
		thing->ceilingdrop = 0;
	}

	if (thing->z > thing->floorz)
	{
		thing->floordrop = 0;
	}

	// Check list of fake floors and see if tm.floorz/tm.ceilingz need to be altered.
	if (newsubsec->sector->ffloors)
	{
		ffloor_t *rover;
		fixed_t delta1, delta2;

		for (rover = newsubsec->sector->ffloors; rover; rover = rover->next)
		{
			fixed_t topheight, bottomheight;

			if (!(rover->fofflags & FOF_EXISTS))
				continue;

			topheight = P_GetFOFTopZ(thing, newsubsec->sector, rover, x, y, NULL);
			bottomheight = P_GetFOFBottomZ(thing, newsubsec->sector, rover, x, y, NULL);

			if ((rover->fofflags & (FOF_SWIMMABLE|FOF_GOOWATER)) == (FOF_SWIMMABLE|FOF_GOOWATER) && !(thing->flags & MF_NOGRAVITY))
			{
				// If you're inside goowater and slowing down
				fixed_t sinklevel = FixedMul(thing->info->height/6, thing->scale);
				fixed_t minspeed = FixedMul(thing->info->height/9, thing->scale);
				if (thing->z < topheight && bottomheight < thingtop
				&& abs(thing->momz) < minspeed)
				{
					// Oh no! The object is stick in between the surface of the goo and sinklevel! help them out!
					if (!(thing->eflags & MFE_VERTICALFLIP) && thing->z > topheight - sinklevel
					&& thing->momz >= 0 && thing->momz < (minspeed>>2))
						thing->momz += minspeed>>2;
					else if (thing->eflags & MFE_VERTICALFLIP && thingtop < bottomheight + sinklevel
					&& thing->momz <= 0 && thing->momz > -(minspeed>>2))
						thing->momz -= minspeed>>2;

					// Land on the top or the bottom, depending on gravity flip.
					if (!(thing->eflags & MFE_VERTICALFLIP) && thing->z >= topheight - sinklevel && thing->momz <= 0)
					{
						if (tm.floorz < topheight - sinklevel)
						{
							tm.floorz = topheight - sinklevel;
							tm.floorrover = rover;
							tm.floorslope = *rover->t_slope;
							tm.floorpic = *rover->toppic;
						}
					}
					else if (thing->eflags & MFE_VERTICALFLIP && thingtop <= bottomheight + sinklevel && thing->momz >= 0)
					{
						if (tm.ceilingz > bottomheight + sinklevel)
						{
							tm.ceilingz = bottomheight + sinklevel;
							tm.ceilingrover = rover;
							tm.ceilingslope = *rover->b_slope;
							tm.ceilingpic = *rover->bottompic;
						}
					}
				}
				continue;
			}

			if (P_CheckSolidFFloorSurface(thing, rover))
				;
			else if (thing->type == MT_SKIM && (rover->fofflags & FOF_SWIMMABLE))
				;
			else if (!((rover->fofflags & FOF_BLOCKPLAYER && thing->player)
			    || (rover->fofflags & FOF_BLOCKOTHERS && !thing->player)
				|| rover->fofflags & FOF_QUICKSAND))
				continue;

			if (rover->fofflags & FOF_QUICKSAND)
			{
				if (thing->z < topheight && bottomheight < thingtop)
				{
					if (tm.floorz < thing->z)
					{
						tm.floorz = thing->z;
						tm.floorrover = rover;
						tm.floorslope = NULL;
						tm.floorpic = *rover->toppic;
					}
				}
				// Quicksand blocks never change heights otherwise.
				continue;
			}

			delta1 = thing->z - (bottomheight
				+ ((topheight - bottomheight)/2));
			delta2 = thingtop - (bottomheight
				+ ((topheight - bottomheight)/2));

			if (topheight > tm.floorz && abs(delta1) < abs(delta2)
				&& !(rover->fofflags & FOF_REVERSEPLATFORM))
			{
				tm.floorz = tm.dropoffz = topheight;
				tm.floorrover = rover;
				tm.floorslope = *rover->t_slope;
				tm.floorpic = *rover->toppic;
			}

			if (bottomheight < tm.ceilingz && abs(delta1) >= abs(delta2)
				&& !(rover->fofflags & FOF_PLATFORM)
				&& !(thing->type == MT_SKIM && (rover->fofflags & FOF_SWIMMABLE)))
			{
				tm.ceilingz = tm.drpoffceilz = bottomheight;
				tm.ceilingrover = rover;
				tm.ceilingslope = *rover->b_slope;
				tm.ceilingpic = *rover->bottompic;
			}
		}
	}

	// The bounding box is extended by MAXRADIUS
	// because mobj_ts are grouped into mapblocks
	// based on their origin point, and can overlap
	// into adjacent blocks by up to MAXRADIUS units.

	xl = (unsigned)(tm.bbox[BOXLEFT] - bmaporgx - MAXRADIUS)>>MAPBLOCKSHIFT;
	xh = (unsigned)(tm.bbox[BOXRIGHT] - bmaporgx + MAXRADIUS)>>MAPBLOCKSHIFT;
	yl = (unsigned)(tm.bbox[BOXBOTTOM] - bmaporgy - MAXRADIUS)>>MAPBLOCKSHIFT;
	yh = (unsigned)(tm.bbox[BOXTOP] - bmaporgy + MAXRADIUS)>>MAPBLOCKSHIFT;

	BMBOUNDFIX(xl, xh, yl, yh);

	// Check polyobjects and see if tm.floorz/tm.ceilingz need to be altered
	{
		validcount++;

		for (by = yl; by <= yh; by++)
		{
			for (bx = xl; bx <= xh; bx++)
			{
				INT32 offset;
				polymaplink_t *plink; // haleyjd 02/22/06

				if (bx < 0 || by < 0 || bx >= bmapwidth || by >= bmapheight)
					continue;

				offset = by*bmapwidth + bx;

				// haleyjd 02/22/06: consider polyobject lines
				plink = polyblocklinks[offset];

				while (plink)
				{
					polyobj_t *po = plink->po;

					if (po->validcount != validcount) // if polyobj hasn't been checked
					{
						sector_t *polysec;
						fixed_t delta1, delta2;
						fixed_t polytop, polybottom;

						po->validcount = validcount;

						if (!P_BBoxInsidePolyobj(po, tm.bbox)
							|| !(po->flags & POF_SOLID))
						{
							plink = (polymaplink_t *)(plink->link.next);
							continue;
						}

						// We're inside it! Yess...
						polysec = po->lines[0]->backsector;

						if (po->flags & POF_CLIPPLANES)
						{
							polytop = polysec->ceilingheight;
							polybottom = polysec->floorheight;
						}
						else
						{
							polytop = INT32_MAX;
							polybottom = INT32_MIN;
						}

						delta1 = thing->z - (polybottom + ((polytop - polybottom)/2));
						delta2 = thingtop - (polybottom + ((polytop - polybottom)/2));

						if (polytop > tm.floorz && abs(delta1) < abs(delta2))
						{
							tm.floorz = tm.dropoffz = polytop;
							tm.floorslope = NULL;
							tm.floorrover = NULL;
							tm.floorpic = polysec->ceilingpic;
						}

						if (polybottom < tm.ceilingz && abs(delta1) >= abs(delta2))
						{
							tm.ceilingz = tm.drpoffceilz = polybottom;
							tm.ceilingslope = NULL;
							tm.ceilingrover = NULL;
							tm.ceilingpic = polysec->floorpic;
						}
					}
					plink = (polymaplink_t *)(plink->link.next);
				}
			}
		}
	}

	// tm.floorthing is set when tm.floorz comes from a thing's top
	P_SetTarget(&tm.floorthing, NULL);
	P_SetTarget(&tm.hitthing, NULL);

	validcount++;

	// reset special lines
	numspechit = 0U;

	// Check things first, possibly picking things up.

	// MF_NOCLIPTHING: used by camera to not be blocked by things
	if (!(thing->flags & MF_NOCLIPTHING))
	{
		for (bx = xl; bx <= xh; bx++)
		{
			for (by = yl; by <= yh; by++)
			{
				if (!P_BlockThingsIterator(bx, by, PIT_CheckThing))
				{
					blockval = false;
				}
				else
				{
					P_SetTarget(&tm.hitthing, tm.floorthing);
				}

				if (P_MobjWasRemoved(tm.thing))
				{
					return false;
				}
			}
		}
	}

	if (tm.flags & MF_NOCLIP)
	{
		// Sal 12/19/2022 -- PIT_CheckThing code will still run
		// with MF_NOCLIP enabled, but they won't be blocked
		// regardless of the result. This allows for SPBs and
		// the UFO to collide.
		return true;
	}

	validcount++;

	// check lines
	for (bx = xl; bx <= xh; bx++)
	{
		for (by = yl; by <= yh; by++)
		{
			if (!P_BlockLinesIterator(bx, by, PIT_CheckLine))
			{
				blockval = false;
			}
		}
	}

	if (result != NULL)
	{
		result->line = tm.blockingline;
		result->mo = tm.hitthing;
	}

	return blockval;
}

static const fixed_t hoopblockdist = 16*FRACUNIT + 8*FRACUNIT;
static const fixed_t hoophalfheight = (56*FRACUNIT)/2;

// P_CheckPosition optimized for the MT_HOOPCOLLIDE object. This needs to be as fast as possible!
void P_CheckHoopPosition(mobj_t *hoopthing, fixed_t x, fixed_t y, fixed_t z, fixed_t radius)
{
	INT32 i;

	(void)radius; //unused
	for (i = 0; i < MAXPLAYERS; i++)
	{
		if (!playeringame[i] || !players[i].mo || players[i].spectator)
			continue;

		if (abs(players[i].mo->x - x) >= hoopblockdist ||
			abs(players[i].mo->y - y) >= hoopblockdist ||
			abs((players[i].mo->z+hoophalfheight) - z) >= hoopblockdist)
			continue; // didn't hit it

		// can remove thing
		P_TouchSpecialThing(hoopthing, players[i].mo, false);
		break;
	}

	return;
}

//
// P_CheckCameraPosition
//
boolean P_CheckCameraPosition(fixed_t x, fixed_t y, camera_t *thiscam)
{
	INT32 xl, xh, yl, yh, bx, by;
	subsector_t *newsubsec;

	tm.x = x;
	tm.y = y;

	tm.bbox[BOXTOP] = y + thiscam->radius;
	tm.bbox[BOXBOTTOM] = y - thiscam->radius;
	tm.bbox[BOXRIGHT] = x + thiscam->radius;
	tm.bbox[BOXLEFT] = x - thiscam->radius;

	newsubsec = R_PointInSubsector(x, y);
	tm.ceilingline = tm.blockingline = NULL;

	mapcampointer = thiscam;

	if (newsubsec->sector->flags & MSF_NOCLIPCAMERA)
	{ // Camera noclip on entire sector.
		tm.floorz = tm.dropoffz = thiscam->z;
		tm.ceilingz = tm.drpoffceilz = thiscam->z + thiscam->height;
		return true;
	}

	// The base floor / ceiling is from the subsector
	// that contains the point.
	// Any contacted lines the step closer together
	// will adjust them.
	tm.floorz = tm.dropoffz = P_CameraGetFloorZ(thiscam, newsubsec->sector, x, y, NULL);

	tm.ceilingz = P_CameraGetCeilingZ(thiscam, newsubsec->sector, x, y, NULL);

	// Cameras use the heightsec's heights rather then the actual sector heights.
	// If you can see through it, why not move the camera through it too?
	if (newsubsec->sector->heightsec >= 0)
	{
		tm.floorz = tm.dropoffz = sectors[newsubsec->sector->heightsec].floorheight;
		tm.ceilingz = tm.drpoffceilz = sectors[newsubsec->sector->heightsec].ceilingheight;
	}

	// Use preset camera clipping heights if set with Sector Special Parameters whose control sector has Camera Intangible special -Red
	if (newsubsec->sector->camsec >= 0)
	{
		tm.floorz = tm.dropoffz = sectors[newsubsec->sector->camsec].floorheight;
		tm.ceilingz = tm.drpoffceilz = sectors[newsubsec->sector->camsec].ceilingheight;
	}

	// Check list of fake floors and see if tm.floorz/tm.ceilingz need to be altered.
	if (newsubsec->sector->ffloors)
	{
		ffloor_t *rover;
		fixed_t delta1, delta2;
		INT32 thingtop = thiscam->z + thiscam->height;

		for (rover = newsubsec->sector->ffloors; rover; rover = rover->next)
		{
			fixed_t topheight, bottomheight;
			if (!(rover->fofflags & FOF_BLOCKOTHERS) || !(rover->fofflags & FOF_EXISTS) || !(rover->fofflags & FOF_RENDERALL) || (rover->master->frontsector->flags & MSF_NOCLIPCAMERA))
				continue;

			topheight = P_CameraGetFOFTopZ(thiscam, newsubsec->sector, rover, x, y, NULL);
			bottomheight = P_CameraGetFOFBottomZ(thiscam, newsubsec->sector, rover, x, y, NULL);

			delta1 = thiscam->z - (bottomheight
				+ ((topheight - bottomheight)/2));
			delta2 = thingtop - (bottomheight
				+ ((topheight - bottomheight)/2));
			if (topheight > tm.floorz && abs(delta1) < abs(delta2))
			{
				tm.floorz = tm.dropoffz = topheight;
			}
			if (bottomheight < tm.ceilingz && abs(delta1) >= abs(delta2))
			{
				tm.ceilingz = tm.drpoffceilz = bottomheight;
			}
		}
	}

	// The bounding box is extended by MAXRADIUS
	// because mobj_ts are grouped into mapblocks
	// based on their origin point, and can overlap
	// into adjacent blocks by up to MAXRADIUS units.

	xl = (unsigned)(tm.bbox[BOXLEFT] - bmaporgx)>>MAPBLOCKSHIFT;
	xh = (unsigned)(tm.bbox[BOXRIGHT] - bmaporgx)>>MAPBLOCKSHIFT;
	yl = (unsigned)(tm.bbox[BOXBOTTOM] - bmaporgy)>>MAPBLOCKSHIFT;
	yh = (unsigned)(tm.bbox[BOXTOP] - bmaporgy)>>MAPBLOCKSHIFT;

	BMBOUNDFIX(xl, xh, yl, yh);

	// Check polyobjects and see if tm.floorz/tm.ceilingz need to be altered
	{
		validcount++;

		for (by = yl; by <= yh; by++)
			for (bx = xl; bx <= xh; bx++)
			{
				INT32 offset;
				polymaplink_t *plink; // haleyjd 02/22/06

				if (bx < 0 || by < 0 || bx >= bmapwidth || by >= bmapheight)
					continue;

				offset = by*bmapwidth + bx;

				// haleyjd 02/22/06: consider polyobject lines
				plink = polyblocklinks[offset];

				while (plink)
				{
					polyobj_t *po = plink->po;

					if (po->validcount != validcount) // if polyobj hasn't been checked
					{
						sector_t *polysec;
						fixed_t delta1, delta2, thingtop;
						fixed_t polytop, polybottom;

						po->validcount = validcount;

						if (!P_PointInsidePolyobj(po, x, y) || !(po->flags & POF_SOLID))
						{
							plink = (polymaplink_t *)(plink->link.next);
							continue;
						}

						// We're inside it! Yess...
						polysec = po->lines[0]->backsector;

						if (polysec->flags & MSF_NOCLIPCAMERA)
						{ // Camera noclip polyobj.
							plink = (polymaplink_t *)(plink->link.next);
							continue;
						}

						if (po->flags & POF_CLIPPLANES)
						{
							polytop = polysec->ceilingheight;
							polybottom = polysec->floorheight;
						}
						else
						{
							polytop = INT32_MAX;
							polybottom = INT32_MIN;
						}

						thingtop = thiscam->z + thiscam->height;
						delta1 = thiscam->z - (polybottom + ((polytop - polybottom)/2));
						delta2 = thingtop - (polybottom + ((polytop - polybottom)/2));

						if (polytop > tm.floorz && abs(delta1) < abs(delta2))
							tm.floorz = tm.dropoffz = polytop;

						if (polybottom < tm.ceilingz && abs(delta1) >= abs(delta2))
							tm.ceilingz = tm.drpoffceilz = polybottom;
					}
					plink = (polymaplink_t *)(plink->link.next);
				}
			}
	}

	// check lines
	for (bx = xl; bx <= xh; bx++)
		for (by = yl; by <= yh; by++)
			if (!P_BlockLinesIterator(bx, by, PIT_CheckCameraLine))
				return false;

	return true;
}

// The highest the camera will "step up" onto another floor.
#define MAXCAMERASTEPMOVE MAXSTEPMOVE

//
// P_TryCameraMove
//
// Attempt to move the camera to a new position
//
// Return true if the move succeeded and no sliding should be done.
//
boolean P_TryCameraMove(fixed_t x, fixed_t y, camera_t *thiscam)
{
	subsector_t *s = R_PointInSubsector(x, y);
	boolean retval = true;

	UINT8 i;

	tm.floatok = false;

	for (i = 0; i <= r_splitscreen; i++)
	{
		if (thiscam == &camera[i])
		{
			// i is now splitscreen cam num
			break;
		}
	}

	if (i > r_splitscreen)
	{
		// Shouldn't happen
		return false;
	}

	if (players[displayplayers[i]].mo)
	{
		fixed_t tryx = thiscam->x;
		fixed_t tryy = thiscam->y;

		if (!(players[displayplayers[i]].pflags & PF_NOCONTEST)) // Time Over should not clip through walls
		{
			tm.floatok = true;
			thiscam->floorz = thiscam->z;
			thiscam->ceilingz = thiscam->z + thiscam->height;
			thiscam->x = x;
			thiscam->y = y;
			thiscam->subsector = s;
			return true;
		}

		do {
			if (x-tryx > MAXRADIUS)
				tryx += MAXRADIUS;
			else if (x-tryx < -MAXRADIUS)
				tryx -= MAXRADIUS;
			else
				tryx = x;
			if (y-tryy > MAXRADIUS)
				tryy += MAXRADIUS;
			else if (y-tryy < -MAXRADIUS)
				tryy -= MAXRADIUS;
			else
				tryy = y;

			if (!P_CheckCameraPosition(tryx, tryy, thiscam))
				return false; // solid wall or thing

			if (tm.ceilingz - tm.floorz < thiscam->height)
				return false; // doesn't fit

			tm.floatok = true;

			if (tm.ceilingz - thiscam->z < thiscam->height)
			{
				if (s == thiscam->subsector && tm.ceilingz >= thiscam->z)
				{
					tm.floatok = true;
					thiscam->floorz = tm.floorz;
					thiscam->ceilingz = tm.floorz + thiscam->height;
					thiscam->x = x;
					thiscam->y = y;
					thiscam->subsector = s;
					return true;
				}
				else
					return false; // mobj must lower itself to fit
			}

			if ((tm.floorz - thiscam->z > MAXCAMERASTEPMOVE))
				return false; // too big a step up
		} while(tryx != x || tryy != y);
	}
	else
	{
		tm.floorz = P_CameraGetFloorZ(thiscam, thiscam->subsector->sector, x, y, NULL);
		tm.ceilingz = P_CameraGetCeilingZ(thiscam, thiscam->subsector->sector, x, y, NULL);
	}

	// the move is ok,
	// so link the thing into its new position

	thiscam->floorz = tm.floorz;
	thiscam->ceilingz = tm.ceilingz;
	thiscam->x = x;
	thiscam->y = y;
	thiscam->subsector = s;

	return retval;
}

//
// PIT_PushableMoved
//
// Move things standing on top
// of pushable things being pushed.
//
static mobj_t *stand;
static fixed_t standx, standy;

BlockItReturn_t PIT_PushableMoved(mobj_t *thing)
{
	fixed_t blockdist;

	if (!(thing->flags & MF_SOLID)
		|| (thing->flags & MF_NOGRAVITY))
		return BMIT_CONTINUE; // Don't move something non-solid!

	// Only pushables are supported... in 2.0. Now players can be moved too!
	if (!(thing->flags & MF_PUSHABLE || thing->player))
		return BMIT_CONTINUE;

	if (thing == stand)
		return BMIT_CONTINUE;

	blockdist = stand->radius + thing->radius;

	if (abs(thing->x - stand->x) >= blockdist || abs(thing->y - stand->y) >= blockdist)
		return BMIT_CONTINUE; // didn't hit it

	if ((!(stand->eflags & MFE_VERTICALFLIP) && thing->z != stand->z + stand->height + FixedMul(FRACUNIT, stand->scale))
	|| ((stand->eflags & MFE_VERTICALFLIP) && thing->z + thing->height != stand->z - FixedMul(FRACUNIT, stand->scale)))
		return BMIT_CONTINUE; // Not standing on top

	if (!stand->momx && !stand->momy)
		return BMIT_CONTINUE;

	// Move this guy!
	if (thing->player)
	{
		// Monster Iestyn - 29/11/13
		// Ridiculous amount of newly declared stuff so players can't get stuck in walls AND so gargoyles don't break themselves at the same time either
		// These are all non-static map variables that are changed for each and every single mobj
		// See, changing player's momx/y would possibly trigger stuff as if the player were running somehow, so this must be done to keep the player standing
		// All this so players can ride gargoyles!
		tm_t oldtm = tm;

		// Move the player
		P_TryMove(thing, thing->x + stand->momx, thing->y + stand->momy, true, NULL);

		// Now restore EVERYTHING so the gargoyle doesn't keep the player's tmstuff and break
		P_RestoreTMStruct(oldtm);

		thing->momz = stand->momz;
	}
	else
	{
		thing->momx = stand->momx;
		thing->momy = stand->momy;
		thing->momz = stand->momz;
	}
	return BMIT_CONTINUE;
}

static boolean P_WaterRunning(mobj_t *thing)
{
	ffloor_t *rover = thing->floorrover;
	return rover && (rover->fofflags & FOF_SWIMMABLE) &&
		P_IsObjectOnGround(thing);
}

static boolean P_WaterStepUp(mobj_t *thing)
{
	return (thing->waterskip > 0 || P_WaterRunning(thing));
}

fixed_t P_BaseStepUp(void)
{
	return FixedMul(MAXSTEPMOVE, mapobjectscale);
}

fixed_t P_GetThingStepUp(mobj_t *thing, fixed_t destX, fixed_t destY)
{
	const fixed_t maxstepmove = P_BaseStepUp();
	fixed_t maxstep = maxstepmove;

	if (P_WaterStepUp(thing) == true)
	{
		// Add some extra stepmove when waterskipping
		maxstep += maxstepmove;
	}

	if (P_MobjTouchingSectorSpecialFlag(thing, SSF_DOUBLESTEPUP)
		|| (R_PointInSubsector(destX, destY)->sector->specialflags & SSF_DOUBLESTEPUP))
	{
		// If using type Section1:13, double the maxstep.
		maxstep <<= 1;
	}
	else if (P_MobjTouchingSectorSpecialFlag(thing, SSF_NOSTEPUP)
		|| (R_PointInSubsector(destX, destY)->sector->specialflags & SSF_NOSTEPUP))
	{
		// If using type Section1:12, no maxstep. For short walls, like Egg Zeppelin
		maxstep = 0;
	}

	return maxstep;
}

static boolean
increment_move
(		mobj_t * thing,
		fixed_t x,
		fixed_t y,
		boolean allowdropoff,
		fixed_t * return_stairjank,
		TryMoveResult_t * result)
{
	fixed_t tryx = thing->x;
	fixed_t tryy = thing->y;
	fixed_t radius = thing->radius;
	fixed_t thingtop;
	fixed_t stairjank = 0;
	tm.floatok = false;

	// reset this to 0 at the start of each trymove call as it's only used here
	numspechitint = 0U;

	// This makes sure that there are no freezes from computing extremely small movements.
	// Originally was MAXRADIUS/2, but that causes some inconsistencies for small players.
	radius = max(radius, mapobjectscale);

	// And Big Large (tm) movements can skip over slopes.
	radius = min(radius, 16*mapobjectscale);

	do {
		// Sal 12/19/2022 -- PIT_CheckThing code now runs
		// with MF_NOCLIP enabled, so we want step-by-step
		// for anything that doesn't have both enabled.
		if ((thing->flags & (MF_NOCLIP|MF_NOCLIPTHING)) == (MF_NOCLIP|MF_NOCLIPTHING))
		{
			tryx = x;
			tryy = y;
		}
		else
		{
			if (x-tryx > radius)
				tryx += radius;
			else if (x-tryx < -radius)
				tryx -= radius;
			else
				tryx = x;

			if (y-tryy > radius)
				tryy += radius;
			else if (y-tryy < -radius)
				tryy -= radius;
			else
				tryy = y;
		}

		if (!P_CheckPosition(thing, tryx, tryy, result))
		{
			return false; // solid wall or thing
		}

		// copy into the spechitint buffer from spechit
		spechitint_copyinto();

		if (!(thing->flags & MF_NOCLIP))
		{
			// All things are affected by their scale.
			fixed_t maxstep = P_GetThingStepUp(thing, tryx, tryy);

			if (tm.ceilingz - tm.floorz < thing->height)
			{
				if (tm.floorthing != NULL)
				{
					P_SetTarget(&tm.hitthing, tm.floorthing);
				}

				return false; // doesn't fit
			}

			tm.floatok = true;

			if (maxstep > 0)
			{
				const boolean flipped =
					(thing->eflags & MFE_VERTICALFLIP) != 0;

				thingtop = thing->z + thing->height;

				// Step up
				if (thing->z < tm.floorz)
				{
					if (tm.floorstep <= maxstep)
					{
						if (!flipped)
							stairjank = tm.floorstep;

						thing->z = thing->floorz = tm.floorz;
						thing->floorrover = tm.floorrover;
						thing->eflags |= MFE_JUSTSTEPPEDDOWN;
					}
					else
					{
						return false; // mobj must raise itself to fit
					}
				}
				else if (tm.ceilingz < thingtop)
				{
					if (tm.ceilingstep <= maxstep)
					{
						if (flipped)
							stairjank = tm.ceilingstep;

						thing->z = ( thing->ceilingz = tm.ceilingz ) - thing->height;
						thing->ceilingrover = tm.ceilingrover;
						thing->eflags |= MFE_JUSTSTEPPEDDOWN;
					}
					else
					{
						return false; // mobj must lower itself to fit
					}
				}
				else if (thing->momz * P_MobjFlip(thing) <= 0 // Step down requires moving down.
					&& !(P_MobjTouchingSectorSpecialFlag(thing, SSF_NOSTEPDOWN)
					|| (R_PointInSubsector(x, y)->sector->specialflags & SSF_NOSTEPDOWN)))
				{
					// If the floor difference is MAXSTEPMOVE or less, and the sector isn't Section1:14, ALWAYS
					// step down! Formerly required a Section1:13 sector for the full MAXSTEPMOVE, but no more.

					if (thingtop == thing->ceilingz && tm.ceilingz > thingtop && tm.ceilingz - thingtop <= maxstep)
					{
						if (flipped)
							stairjank = (tm.ceilingz - thingtop);

						thing->z = (thing->ceilingz = tm.ceilingz) - thing->height;
						thing->ceilingrover = tm.ceilingrover;
						thing->eflags |= MFE_JUSTSTEPPEDDOWN;
						thing->ceilingdrop = 0;
					}
					else if (thing->z == thing->floorz && tm.floorz < thing->z && thing->z - tm.floorz <= maxstep)
					{
						if (!flipped)
							stairjank = (thing->z - tm.floorz);

						thing->z = thing->floorz = tm.floorz;
						thing->floorrover = tm.floorrover;
						thing->eflags |= MFE_JUSTSTEPPEDDOWN;
						thing->floordrop = 0;
					}
				}
			}

			if (!allowdropoff && !(thing->flags & MF_FLOAT) && thing->type != MT_SKIM && !tm.floorthing)
			{
				if (thing->eflags & MFE_VERTICALFLIP)
				{
					if (tm.drpoffceilz - tm.ceilingz > maxstep)
						return false;
				}
				else if (tm.floorz - tm.dropoffz > maxstep)
					return false; // don't stand over a dropoff
			}
		}
	} while (tryx != x || tryy != y);

	if (return_stairjank)
	{
		*return_stairjank = stairjank;
	}

	return true;
}

//
// P_CheckMove
// Check if a P_TryMove would be successful.
//
boolean P_CheckMove(mobj_t *thing, fixed_t x, fixed_t y, boolean allowdropoff, TryMoveResult_t *result)
{
	boolean moveok = false;
	mobj_t *hack = P_SpawnMobjFromMobj(thing, 0, 0, 0, MT_RAY);

	hack->radius = thing->radius;
	hack->height = thing->height;

	moveok = increment_move(hack, x, y, allowdropoff, NULL, result);
	P_RemoveMobj(hack);

	return moveok;
}

//
// P_TryMove
// Attempt to move to a new position.
//
boolean P_TryMove(mobj_t *thing, fixed_t x, fixed_t y, boolean allowdropoff, TryMoveResult_t *result)
{
	fixed_t oldx = thing->x;
	fixed_t oldy = thing->y;
	fixed_t startingonground = P_IsObjectOnGround(thing);
	fixed_t stairjank = 0;
	pslope_t *oldslope = thing->standingslope;

	// Is the move OK?
	if (increment_move(thing, x, y, allowdropoff, &stairjank, result) == false)
	{
		if (result != NULL)
		{
			result->success = false;
		}
		return false;
	}

	// If it's a pushable object, check if anything is
	// standing on top and move it, too.
	if (thing->flags & MF_PUSHABLE)
	{
		INT32 bx, by, xl, xh, yl, yh;

		yh = (unsigned)(thing->y + MAXRADIUS - bmaporgy)>>MAPBLOCKSHIFT;
		yl = (unsigned)(thing->y - MAXRADIUS - bmaporgy)>>MAPBLOCKSHIFT;
		xh = (unsigned)(thing->x + MAXRADIUS - bmaporgx)>>MAPBLOCKSHIFT;
		xl = (unsigned)(thing->x - MAXRADIUS - bmaporgx)>>MAPBLOCKSHIFT;

		BMBOUNDFIX(xl, xh, yl, yh);

		stand = thing;
		standx = x;
		standy = y;

		for (by = yl; by <= yh; by++)
			for (bx = xl; bx <= xh; bx++)
				P_BlockThingsIterator(bx, by, PIT_PushableMoved);
	}

	// Link the thing into its new position
	P_UnsetThingPosition(thing);

	thing->floorz = tm.floorz;
	thing->ceilingz = tm.ceilingz;
	thing->floorrover = tm.floorrover;
	thing->ceilingrover = tm.ceilingrover;

	if (!(thing->flags & MF_NOCLIPHEIGHT))
	{
		// Assign thing's standingslope if needed
		if (thing->z <= tm.floorz && !(thing->eflags & MFE_VERTICALFLIP))
		{
			K_UpdateMobjTerrain(thing, tm.floorpic);

			if (!startingonground && tm.floorslope)
			{
				P_HandleSlopeLanding(thing, tm.floorslope);
			}

			if (thing->momz <= 0)
			{
				angle_t oldPitch = thing->pitch;
				angle_t oldRoll = thing->roll;

				thing->standingslope = tm.floorslope;
				P_SetPitchRollFromSlope(thing, thing->standingslope);

				if (thing->player)
				{
					P_PlayerHitFloor(thing->player, !startingonground, oldPitch, oldRoll);
				}
			}
		}
		else if (thing->z+thing->height >= tm.ceilingz && (thing->eflags & MFE_VERTICALFLIP))
		{
			K_UpdateMobjTerrain(thing, tm.ceilingpic);

			if (!startingonground && tm.ceilingslope)
			{
				P_HandleSlopeLanding(thing, tm.ceilingslope);
			}

			if (thing->momz >= 0)
			{
				angle_t oldPitch = thing->pitch;
				angle_t oldRoll = thing->roll;

				thing->standingslope = tm.ceilingslope;
				P_SetPitchRollFromSlope(thing, thing->standingslope);

				if (thing->player)
				{
					P_PlayerHitFloor(thing->player, !startingonground, oldPitch, oldRoll);
				}
			}
		}
	}
	else
	{
		// don't set standingslope if you're not going to clip against it
		thing->standingslope = NULL;
		thing->terrain = NULL;
	}

	if (thing->player && K_IsRidingFloatingTop(thing->player))
	{
		stairjank = false;
	}

	/* FIXME: slope step down (even up) has some false
		positives, so just ignore them entirely. */
	if (stairjank && !oldslope && !thing->standingslope &&
			thing->player && !thing->player->spectator)
	{
		/* use a shorter sound if not two tics have passed
		 * since the last step */
		S_ReducedVFXSound(thing, thing->player->stairjank
				>= 16 ?  sfx_s23b : sfx_s268, NULL);

		if (!thing->player->stairjank)
		{
			mobj_t * spark = P_SpawnMobjFromMobj(thing,
					0, 0, 0, MT_JANKSPARK);
			spark->fuse = 9;
			spark->cusval = K_StairJankFlip(ANGLE_90);
			P_SetTarget(&spark->target, thing);
			K_ReduceVFX(spark, thing->player);
		}

		thing->player->stairjank = 17;
	}

	thing->x = x;
	thing->y = y;

	if (tm.floorthing)
		thing->eflags &= ~MFE_ONGROUND; // not on real floor
	else
		thing->eflags |= MFE_ONGROUND;

	P_SetThingPosition(thing);

	// remove any duplicates that may be in spechitint
	spechitint_removedups();

	// handle any of the special lines that were crossed
	if (!(thing->flags & (MF_NOCLIP)))
	{
		line_t *ld = NULL;
		INT32 side = 0, oldside = 0;
		while (numspechitint--)
		{
			ld = &lines[spechitint[numspechitint]];
			side = P_PointOnLineSide(thing->x, thing->y, ld);
			oldside = P_PointOnLineSide(oldx, oldy, ld);
			if (side != oldside)
			{
				P_CrossSpecialLine(ld, oldside, thing);
			}
		}
	}

	if (result != NULL)
	{
		result->success = true;
	}

	return true;
}

boolean P_SceneryTryMove(mobj_t *thing, fixed_t x, fixed_t y, TryMoveResult_t *result)
{
	fixed_t tryx, tryy;

	tryx = thing->x;
	tryy = thing->y;
	do {
		if (x-tryx > MAXRADIUS)
			tryx += MAXRADIUS;
		else if (x-tryx < -MAXRADIUS)
			tryx -= MAXRADIUS;
		else
			tryx = x;
		if (y-tryy > MAXRADIUS)
			tryy += MAXRADIUS;
		else if (y-tryy < -MAXRADIUS)
			tryy -= MAXRADIUS;
		else
			tryy = y;

		if (!P_CheckPosition(thing, tryx, tryy, result))
			return false; // solid wall or thing

		if (!(thing->flags & MF_NOCLIP))
		{
			const fixed_t maxstep = P_BaseStepUp();

			if (tm.ceilingz - tm.floorz < thing->height)
				return false; // doesn't fit

			if (tm.ceilingz - thing->z < thing->height)
				return false; // mobj must lower itself to fit

			if (tm.floorz - thing->z > maxstep)
				return false; // too big a step up
		}
	} while(tryx != x || tryy != y);

	// the move is ok,
	// so link the thing into its new position
	P_UnsetThingPosition(thing);

	thing->floorz = tm.floorz;
	thing->ceilingz = tm.ceilingz;
	thing->floorrover = tm.floorrover;
	thing->ceilingrover = tm.ceilingrover;
	thing->x = x;
	thing->y = y;

	if (tm.floorthing)
		thing->eflags &= ~MFE_ONGROUND; // not on real floor
	else
		thing->eflags |= MFE_ONGROUND;

	P_SetThingPosition(thing);
	return true;
}

//
// PTR_GetSpecialLines
//
static boolean PTR_GetSpecialLines(intercept_t *in)
{
	line_t *ld;

	I_Assert(in->isaline);

	ld = in->d.line;

	if (!ld->backsector)
	{
		return true;
	}

	if (P_SpecialIsLinedefCrossType(ld))
	{
		add_spechit(ld);
	}

	return true;
}

//
// P_HitSpecialLines
// Finds all special lines in the provided path and tries to cross them.
// For zoom tubes and respawning, which noclip but need to cross finish lines.
//
void P_HitSpecialLines(mobj_t *thing, fixed_t x, fixed_t y, fixed_t momx, fixed_t momy)
{
	fixed_t leadx, leady;
	fixed_t trailx, traily;
	line_t *ld = NULL;
	INT32 side = 0, oldside = 0;

	I_Assert(thing != NULL);
#ifdef PARANOIA
	if (P_MobjWasRemoved(thing))
		I_Error("Previously-removed Thing of type %u crashes P_CheckPosition!", thing->type);
#endif

	// reset special lines
	numspechitint = 0U;
	numspechit = 0U;

	// trace along the three leading corners
	if (momx > 0)
	{
		leadx = x + thing->radius;
		trailx = x - thing->radius;
	}
	else
	{
		leadx = x - thing->radius;
		trailx = x + thing->radius;
	}

	if (momy > 0)
	{
		leady = y + thing->radius;
		traily = y - thing->radius;
	}
	else
	{
		leady = y - thing->radius;
		traily = y + thing->radius;
	}

	P_PathTraverse(leadx, leady, leadx + momx, leady + momy, PT_ADDLINES, PTR_GetSpecialLines);
	P_PathTraverse(trailx, leady, trailx + momx, leady + momy, PT_ADDLINES, PTR_GetSpecialLines);
	P_PathTraverse(leadx, traily, leadx + momx, traily + momy, PT_ADDLINES, PTR_GetSpecialLines);

	spechitint_copyinto();

	// remove any duplicates that may be in spechitint
	spechitint_removedups();

	// handle any of the special lines that were crossed
	while (numspechitint--)
	{
		ld = &lines[spechitint[numspechitint]];
		side = P_PointOnLineSide(x + momx, y + momy, ld);
		oldside = P_PointOnLineSide(x, y, ld);
		if (side != oldside)
		{
			P_CrossSpecialLine(ld, oldside, thing);
		}
	}
}

//
// P_ThingHeightClip
// Takes a valid thing and adjusts the thing->floorz,
// thing->ceilingz, and possibly thing->z.
// This is called for all nearby monsters
// whenever a sector changes height.
// If the thing doesn't fit,
// the z will be set to the lowest value
// and false will be returned.
//
static boolean P_ThingHeightClip(mobj_t *thing)
{
	boolean floormoved;
	fixed_t oldfloorz = thing->floorz, oldz = thing->z;
	ffloor_t *oldfloorrover = thing->floorrover;
	ffloor_t *oldceilingrover = thing->ceilingrover;
	boolean onfloor = P_IsObjectOnGround(thing);//(thing->z <= thing->floorz);
	ffloor_t *rover = NULL;
	boolean hitfloor = false;

	if (thing->flags & MF_NOCLIPHEIGHT)
		return true;

	P_CheckPosition(thing, thing->x, thing->y, NULL);

	if (P_MobjWasRemoved(thing))
		return true;

	floormoved = (thing->eflags & MFE_VERTICALFLIP && tm.ceilingz != thing->ceilingz)
		|| (!(thing->eflags & MFE_VERTICALFLIP) && tm.floorz != thing->floorz);

	thing->floorz = tm.floorz;
	thing->ceilingz = tm.ceilingz;
	thing->floorrover = tm.floorrover;
	thing->ceilingrover = tm.ceilingrover;

	// Ugly hack?!?! As long as just ceilingz is the lowest,
	// you'll still get crushed, right?
	if (tm.floorz > oldfloorz+thing->height)
		return true;

	if (onfloor && !(thing->flags & MF_NOGRAVITY) && floormoved)
	{
		rover = (thing->eflags & MFE_VERTICALFLIP) ? oldceilingrover : oldfloorrover;

		// Match the Thing's old floorz to an FOF and check for FOF_EXISTS
		// If ~FOF_EXISTS, don't set mobj Z.
		if (!rover || ((rover->fofflags & FOF_EXISTS) && (rover->fofflags & FOF_SOLID)))
		{
			hitfloor = false;
			if (thing->eflags & MFE_VERTICALFLIP)
				thing->pmomz = thing->ceilingz - (thing->z + thing->height);
			else
				thing->pmomz = thing->floorz - thing->z;
			thing->eflags |= MFE_APPLYPMOMZ;

			if (thing->eflags & MFE_VERTICALFLIP)
				thing->z = thing->ceilingz - thing->height;
			else
				thing->z = thing->floorz;
		}
	}
	else if (!tm.floorthing)
	{
		// don't adjust a floating monster unless forced to
		if (thing->eflags & MFE_VERTICALFLIP)
		{
			if (!onfloor && thing->z < tm.floorz)
				thing->z = thing->floorz;
		}
		else if (!onfloor && thing->z + thing->height > tm.ceilingz)
			thing->z = thing->ceilingz - thing->height;
	}

	if ((P_MobjFlip(thing)*(thing->z - oldz) > 0 || hitfloor) && thing->player)
		P_PlayerHitFloor(thing->player, !onfloor, thing->pitch, thing->roll);

	// debug: be sure it falls to the floor
	thing->eflags &= ~MFE_ONGROUND;

	if (thing->ceilingz - thing->floorz < thing->height && thing->z >= thing->floorz)
		// BP: i know that this code cause many trouble but this also fixes
		// a lot of problems, mainly this is implementation of the stepping
		// for mobj (walk on solid corpse without jumping or fake 3d bridge)
		// problem is imp into imp at map01 and monster going at top of others
		return false;

	return true;
}

//
// SLIDE MOVE
// Allows the player to slide along any angled walls.
//
static fixed_t bestslidefrac, secondslidefrac;
static line_t *bestslideline;
static line_t *secondslideline;
static mobj_t *slidemo;
static fixed_t tmxmove, tmymove;

//
// P_HitCameraSlideLine
//
static void P_HitCameraSlideLine(line_t *ld, camera_t *thiscam)
{
	INT32 side;
	angle_t lineangle, moveangle, deltaangle;
	fixed_t movelen, newlen;

	if (ld->slopetype == ST_HORIZONTAL)
	{
		tmymove = 0;
		return;
	}

	if (ld->slopetype == ST_VERTICAL)
	{
		tmxmove = 0;
		return;
	}

	side = P_PointOnLineSide(thiscam->x, thiscam->y, ld);
	lineangle = ld->angle;

	if (side == 1)
		lineangle += ANGLE_180;

	moveangle = R_PointToAngle2(0, 0, tmxmove, tmymove);
	deltaangle = moveangle-lineangle;

	if (deltaangle > ANGLE_180)
		deltaangle += ANGLE_180;

	lineangle >>= ANGLETOFINESHIFT;
	deltaangle >>= ANGLETOFINESHIFT;

	movelen = P_AproxDistance(tmxmove, tmymove);
	newlen = FixedMul(movelen, FINECOSINE(deltaangle));

	tmxmove = FixedMul(newlen, FINECOSINE(lineangle));
	tmymove = FixedMul(newlen, FINESINE(lineangle));
}

//
// P_HitSlideLine
// Adjusts the xmove / ymove
// so that the next move will slide along the wall.
//
static void P_HitSlideLine(line_t *ld)
{
	INT32 side;
	angle_t lineangle;
	fixed_t nx, ny;
	fixed_t d;

	side = P_PointOnLineSide(slidemo->x, slidemo->y, ld);
	lineangle = ld->angle - ANGLE_90;

	if (side == 1)
		lineangle += ANGLE_180;

	lineangle >>= ANGLETOFINESHIFT;

	nx = FINECOSINE(lineangle);
	ny = FINESINE(lineangle);

	d = FixedMul(tmxmove, nx) + FixedMul(tmymove, ny);

	tmxmove -= FixedMul(nx, d);
	tmymove -= FixedMul(ny, d);
}

//
// P_PlayerHitBounceLine
//
// HitBounceLine, for players
//
static void P_PlayerHitBounceLine(line_t *ld)
{
	INT32 side;
	angle_t lineangle;
	fixed_t movelen;
	fixed_t x, y;

	side = P_PointOnLineSide(slidemo->x, slidemo->y, ld);
	lineangle = ld->angle - ANGLE_90;

	if (side == 1)
		lineangle += ANGLE_180;

	lineangle >>= ANGLETOFINESHIFT;

	movelen = P_AproxDistance(tmxmove, tmymove);

	if (slidemo->player && movelen < (15*mapobjectscale))
		movelen = (15*mapobjectscale);

	x = FixedMul(movelen, FINECOSINE(lineangle));
	y = FixedMul(movelen, FINESINE(lineangle));

	if (P_IsLineTripWire(ld))
	{
		tmxmove = x * 4;
		tmymove = y * 4;
	}
	else
	{
		tmxmove += x;
		tmymove += y;
	}
}

//
// P_HitBounceLine
//
// Adjusts the xmove / ymove so that the next move will bounce off the wall.
//
static void P_HitBounceLine(line_t *ld)
{
	angle_t lineangle, moveangle, deltaangle;
	fixed_t movelen;

	if (ld->slopetype == ST_HORIZONTAL)
	{
		tmymove = -tmymove;
		return;
	}

	if (ld->slopetype == ST_VERTICAL)
	{
		tmxmove = -tmxmove;
		return;
	}

	lineangle = ld->angle;

	if (lineangle >= ANGLE_180)
		lineangle -= ANGLE_180;

	moveangle = R_PointToAngle2(0, 0, tmxmove, tmymove);
	deltaangle = moveangle + 2*(lineangle - moveangle);

	lineangle >>= ANGLETOFINESHIFT;
	deltaangle >>= ANGLETOFINESHIFT;

	movelen = P_AproxDistance(tmxmove, tmymove);

	tmxmove = FixedMul(movelen, FINECOSINE(deltaangle));
	tmymove = FixedMul(movelen, FINESINE(deltaangle));

	deltaangle = R_PointToAngle2(0, 0, tmxmove, tmymove);
}

//
// PTR_SlideCameraTraverse
//
static boolean PTR_SlideCameraTraverse(intercept_t *in)
{
	line_t *li;

	I_Assert(in->isaline);

	li = in->d.line;

	// one-sided linedef
	if (!li->backsector)
	{
		if (P_PointOnLineSide(mapcampointer->x, mapcampointer->y, li))
			return true; // don't hit the back side
		goto isblocking;
	}

	// set openrange, opentop, openbottom
	P_CameraLineOpening(li);

	if (openrange < mapcampointer->height)
		goto isblocking; // doesn't fit

	if (opentop - mapcampointer->z < mapcampointer->height)
		goto isblocking; // mobj is too high

	if (openbottom - mapcampointer->z > 0) // We don't want to make the camera step up.
		goto isblocking; // too big a step up

	// this line doesn't block movement
	return true;

	// the line does block movement,
	// see if it is closer than best so far
isblocking:
	{
		if (in->frac < bestslidefrac)
		{
			secondslidefrac = bestslidefrac;
			secondslideline = bestslideline;
			bestslidefrac = in->frac;
			bestslideline = li;
		}
	}

	return false; // stop
}

/*
static boolean PTR_LineIsBlocking(line_t *li)
{
	// one-sided linedefs are always solid to sliding movement.
	if (!li->backsector)
		return !P_PointOnLineSide(slidemo->x, slidemo->y, li);

	if (P_IsLineBlocking(li, slidemo))
		return true;

	// set openrange, opentop, openbottom
	P_LineOpening(li, slidemo);

	if (openrange < slidemo->height)
		return true; // doesn't fit

	if (opentop - slidemo->z < slidemo->height)
		return true; // mobj is too high

	if (openbottom - slidemo->z > P_GetThingStepUp(slidemo, slidemo->x, slidemo->y))
		return true; // too big a step up

	return false;
}
*/

/*
static boolean PTR_SlideTraverse(intercept_t *in)
{
	line_t *li;

	I_Assert(in->isaline);

	li = in->d.line;

	if (!PTR_LineIsBlocking(li))
		return true;

	// the line blocks movement,
	// see if it is closer than best so far
	if (li->polyobj && slidemo->player)
	{
		if ((li->polyobj->lines[0]->backsector->flags & MSF_TRIGGERSPECIAL_TOUCH) && !(li->polyobj->flags & POF_NOSPECIALS))
			P_ProcessSpecialSector(slidemo->player, slidemo->subsector->sector, li->polyobj->lines[0]->backsector);
	}

	if (in->frac < bestslidefrac)
	{
		secondslidefrac = bestslidefrac;
		secondslideline = bestslideline;
		bestslidefrac = in->frac;
		bestslideline = li;
	}

	return false; // stop
}
*/

//
// P_SlideCameraMove
//
// Tries to slide the camera along a wall.
//
void P_SlideCameraMove(camera_t *thiscam)
{
	fixed_t leadx, leady, trailx, traily, newx, newy;
	INT32 hitcount = 0;
	INT32 retval = 0;

	bestslideline = NULL;

retry:
	if (++hitcount == 3)
		goto stairstep; // don't loop forever

	// trace along the three leading corners
	if (thiscam->momx > 0)
	{
		leadx = thiscam->x + thiscam->radius;
		trailx = thiscam->x - thiscam->radius;
	}
	else
	{
		leadx = thiscam->x - thiscam->radius;
		trailx = thiscam->x + thiscam->radius;
	}

	if (thiscam->momy > 0)
	{
		leady = thiscam->y + thiscam->radius;
		traily = thiscam->y - thiscam->radius;
	}
	else
	{
		leady = thiscam->y - thiscam->radius;
		traily = thiscam->y + thiscam->radius;
	}

	bestslidefrac = FRACUNIT+1;

	mapcampointer = thiscam;

	P_PathTraverse(leadx, leady, leadx + thiscam->momx, leady + thiscam->momy,
		PT_ADDLINES, PTR_SlideCameraTraverse);
	P_PathTraverse(trailx, leady, trailx + thiscam->momx, leady + thiscam->momy,
		PT_ADDLINES, PTR_SlideCameraTraverse);
	P_PathTraverse(leadx, traily, leadx + thiscam->momx, traily + thiscam->momy,
		PT_ADDLINES, PTR_SlideCameraTraverse);

	// move up to the wall
	if (bestslidefrac == FRACUNIT+1)
	{
		retval = P_TryCameraMove(thiscam->x, thiscam->y + thiscam->momy, thiscam);
		// the move must have hit the middle, so stairstep
stairstep:
		if (!retval) // Allow things to drop off.
			P_TryCameraMove(thiscam->x + thiscam->momx, thiscam->y, thiscam);
		return;
	}

	// fudge a bit to make sure it doesn't hit
	bestslidefrac -= 0x800;
	if (bestslidefrac > 0)
	{
		newx = FixedMul(thiscam->momx, bestslidefrac);
		newy = FixedMul(thiscam->momy, bestslidefrac);

		retval = P_TryCameraMove(thiscam->x + newx, thiscam->y + newy, thiscam);

		if (!retval)
			goto stairstep;
	}

	// Now continue along the wall.
	// First calculate remainder.
	bestslidefrac = FRACUNIT - (bestslidefrac+0x800);

	if (bestslidefrac > FRACUNIT)
		bestslidefrac = FRACUNIT;

	if (bestslidefrac <= 0)
		return;

	tmxmove = FixedMul(thiscam->momx, bestslidefrac);
	tmymove = FixedMul(thiscam->momy, bestslidefrac);

	P_HitCameraSlideLine(bestslideline, thiscam); // clip the moves

	thiscam->momx = tmxmove;
	thiscam->momy = tmymove;

	retval = P_TryCameraMove(thiscam->x + tmxmove, thiscam->y + tmymove, thiscam);

	if (!retval)
		goto retry;
}

static void P_CheckLavaWall(mobj_t *mo, sector_t *sec)
{
	ffloor_t *rover;
	fixed_t topheight, bottomheight;

	for (rover = sec->ffloors; rover; rover = rover->next)
	{
		if (!(rover->fofflags & FOF_EXISTS))
			continue;

		if (!(rover->fofflags & FOF_SWIMMABLE))
			continue;

		if (rover->master->frontsector->damagetype != SD_LAVA)
			continue;

		topheight = P_GetFFloorTopZAt(rover, mo->x, mo->y);

		if (mo->eflags & MFE_VERTICALFLIP)
		{
			if (topheight < mo->z - mo->height)
				continue;
		}
		else
		{
			if (topheight < mo->z)
				continue;
		}

		bottomheight = P_GetFFloorBottomZAt(rover, mo->x, mo->y);

		if (mo->eflags & MFE_VERTICALFLIP)
		{
			if (bottomheight > mo->z)
				continue;
		}
		else
		{
			if (bottomheight > mo->z + mo->height)
				continue;
		}

		P_DamageMobj(mo, NULL, NULL, 1, DMG_NORMAL);
		return;
	}
}

//
// P_SlideMove
// The momx / momy move is bad, so try to slide
// along a wall.
// Find the first line hit, move flush to it,
// and slide along it
//
// This is a kludgy mess.
//
void P_SlideMove(mobj_t *mo, TryMoveResult_t *result)
{
	fixed_t newx, newy;
	boolean success = false;

	vertex_t v1, v2; // fake vertexes
	line_t junk; // fake linedef

	if (P_MobjWasRemoved(mo))
		return;

	if (result == NULL)
		return;

	if (result->mo && mo->z + mo->height > result->mo->z && mo->z < result->mo->z + result->mo->height)
	{
		// Don't mess with your momentum if it's a pushable object. Pushables do their own crazy things already.
		if (result->mo->flags & MF_PUSHABLE)
			return;

		if (result->mo->flags & MF_PAPERCOLLISION)
		{
			fixed_t cosradius, sinradius;

			slidemo = mo;
			bestslideline = &junk;

			cosradius = FixedMul(result->mo->radius, FINECOSINE(result->mo->angle>>ANGLETOFINESHIFT));
			sinradius = FixedMul(result->mo->radius, FINESINE(result->mo->angle>>ANGLETOFINESHIFT));

			v1.x = result->mo->x - cosradius;
			v1.y = result->mo->y - sinradius;
			v2.x = result->mo->x + cosradius;
			v2.y = result->mo->y + sinradius;

			// gotta fuck around with a fake linedef!
			junk.v1 = &v1;
			junk.v2 = &v2;
			junk.dx = 2*cosradius; // v2.x - v1.x;
			junk.dy = 2*sinradius; // v2.y - v1.y;

			junk.slopetype = !cosradius ? ST_VERTICAL : !sinradius ? ST_HORIZONTAL :
				((sinradius > 0) == (cosradius > 0)) ? ST_POSITIVE : ST_NEGATIVE;

			goto papercollision;
		}

		// Thankfully box collisions are a lot simpler than arbitrary lines. There's only four possible cases.
		if (mo->y + mo->radius <= result->mo->y - result->mo->radius)
		{
			mo->momy = 0;
			P_TryMove(mo, mo->x + mo->momx, result->mo->y - result->mo->radius - mo->radius, true, NULL);
		}
		else if (mo->y - mo->radius >= result->mo->y + result->mo->radius)
		{
			mo->momy = 0;
			P_TryMove(mo, mo->x + mo->momx, result->mo->y + result->mo->radius + mo->radius, true, NULL);
		}
		else if (mo->x + mo->radius <= result->mo->x - result->mo->radius)
		{
			mo->momx = 0;
			P_TryMove(mo, result->mo->x - result->mo->radius - mo->radius, mo->y + mo->momy, true, NULL);
		}
		else if (mo->x - mo->radius >= result->mo->x + result->mo->radius)
		{
			mo->momx = 0;
			P_TryMove(mo, result->mo->x + result->mo->radius + mo->radius, mo->y + mo->momy, true, NULL);
		}
		else
			mo->momx = mo->momy = 0;

		return;
	}

	slidemo = mo;
	bestslideline = result->line;

	if (bestslideline == NULL)
		return;

	if (bestslideline && mo->player && bestslideline->sidenum[1] != 0xffff)
	{
		sector_t *sec = P_PointOnLineSide(mo->x, mo->y, bestslideline) ? bestslideline->frontsector : bestslideline->backsector;
		P_CheckLavaWall(mo, sec);
	}

papercollision:
	tmxmove = mo->momx;
	tmymove = mo->momy;

	P_HitSlideLine(bestslideline); // clip the moves

	mo->momx = tmxmove;
	mo->momy = tmymove;

	do {
		if (tmxmove > mo->radius)
		{
			newx = mo->x + mo->radius;
			tmxmove -= mo->radius;
		}
		else if (tmxmove < -mo->radius)
		{
			newx = mo->x - mo->radius;
			tmxmove += mo->radius;
		}
		else
		{
			newx = mo->x + tmxmove;
			tmxmove = 0;
		}

		if (tmymove > mo->radius)
		{
			newy = mo->y + mo->radius;
			tmymove -= mo->radius;
		}
		else if (tmymove < -mo->radius)
		{
			newy = mo->y - mo->radius;
			tmymove += mo->radius;
		}
		else
		{
			newy = mo->y + tmymove;
			tmymove = 0;
		}

		if (!P_TryMove(mo, newx, newy, true, NULL))
		{
			if (success || P_MobjWasRemoved(mo))
				return; // Good enough!!

			// the move must have hit the middle, so stairstep
			if (!P_TryMove(mo, mo->x, mo->y + mo->momy, true, NULL)) // Allow things to drop off.
				P_TryMove(mo, mo->x + mo->momx, mo->y, true, NULL);
			return;
		}
		success = true;
	} while(tmxmove || tmymove);
}

//
// P_BouncePlayerMove
//
// Bounce move, for players.
//

static void P_BouncePlayerMove(mobj_t *mo, TryMoveResult_t *result)
{
	fixed_t mmomx = 0, mmomy = 0;
	fixed_t oldmomx = mo->momx, oldmomy = mo->momy;

	if (P_MobjWasRemoved(mo) == true)
		return;

	if (mo->player == NULL)
		return;

	if (result == NULL)
		return;

	if (mo->player->spectator)
	{
		P_SlideMove(mo, result);
		return;
	}

	mmomx = mo->player->rmomx;
	mmomy = mo->player->rmomy;

	slidemo = mo;
	bestslideline = result->line;

	if (bestslideline == NULL)
		return;

	if (mo->eflags & MFE_JUSTBOUNCEDWALL) // Stronger push-out
	{
		tmxmove = mmomx;
		tmymove = mmomy;
	}
	else
	{
		tmxmove = FixedMul(mmomx, (FRACUNIT - (FRACUNIT>>2) - (FRACUNIT>>3)));
		tmymove = FixedMul(mmomy, (FRACUNIT - (FRACUNIT>>2) - (FRACUNIT>>3)));
	}

	if (P_IsLineTripWire(bestslideline))
	{
		// TRIPWIRE CANNOT BE MADE NONBOUNCY
		K_ApplyTripWire(mo->player, TRIPSTATE_BLOCKED);
	}
	else
	{
		// Some walls aren't bouncy even if you are
		if (bestslideline && (bestslideline->flags & ML_NOTBOUNCY))
		{
			// SRB2Kart: Non-bouncy line!
			P_SlideMove(mo, result);
			return;
		}

		K_SpawnBumpEffect(mo);
	}

	P_PlayerHitBounceLine(bestslideline);
	mo->eflags |= MFE_JUSTBOUNCEDWALL;

	mo->momx = tmxmove;
	mo->momy = tmymove;
	mo->player->cmomx = tmxmove;
	mo->player->cmomy = tmymove;

	if (!P_IsLineTripWire(bestslideline))
	{
		if (!P_TryMove(mo, mo->x + tmxmove, mo->y + tmymove, true, NULL))
		{
			P_TryMove(mo, mo->x - oldmomx, mo->y - oldmomy, true, NULL);
		}
	}
}

//
// P_BounceMove
//
// The momx / momy move is bad, so try to bounce off a wall.
//
void P_BounceMove(mobj_t *mo, TryMoveResult_t *result)
{
	fixed_t mmomx = 0, mmomy = 0;

	if (P_MobjWasRemoved(mo))
		return;

	if (mo->player)
	{
		P_BouncePlayerMove(mo, result);
		return;
	}

	if (mo->eflags & MFE_JUSTBOUNCEDWALL)
	{
		P_SlideMove(mo, result);
		return;
	}

	mmomx = mo->momx;
	mmomy = mo->momy;

	slidemo = mo;
	bestslideline = result->line;

	if (bestslideline == NULL)
		return;

	if (mo->type == MT_SHELL)
	{
		tmxmove = mmomx;
		tmymove = mmomy;
	}
	else if (mo->type == MT_THROWNBOUNCE)
	{
		tmxmove = FixedMul(mmomx, (FRACUNIT - (FRACUNIT>>6) - (FRACUNIT>>5)));
		tmymove = FixedMul(mmomy, (FRACUNIT - (FRACUNIT>>6) - (FRACUNIT>>5)));
	}
	else if (mo->type == MT_THROWNGRENADE)
	{
		// Quickly decay speed as it bounces
		tmxmove = FixedDiv(mmomx, 2*FRACUNIT);
		tmymove = FixedDiv(mmomy, 2*FRACUNIT);
	}
	else
	{
		tmxmove = FixedMul(mmomx, (FRACUNIT - (FRACUNIT>>2) - (FRACUNIT>>3)));
		tmymove = FixedMul(mmomy, (FRACUNIT - (FRACUNIT>>2) - (FRACUNIT>>3)));
	}

	P_HitBounceLine(bestslideline); // clip the moves

	mo->momx = tmxmove;
	mo->momy = tmymove;

	if (!P_TryMove(mo, mo->x + tmxmove, mo->y + tmymove, true, NULL))
	{
		if (P_MobjWasRemoved(mo))
			return;

		// the move must have hit the middle, so bounce straight back
		mo->momx *= -1;
		mo->momy *= -1;
		mo->momx = FixedMul(mo->momx, (FRACUNIT - (FRACUNIT>>2) - (FRACUNIT>>3)));
		mo->momy = FixedMul(mo->momy, (FRACUNIT - (FRACUNIT>>2) - (FRACUNIT>>3)));
	}
}

//
// RADIUS ATTACK
//
static fixed_t bombdamage;
static mobj_t *bombsource;
static mobj_t *bombspot;
static UINT8 bombdamagetype;
static boolean bombsightcheck;

//
// PIT_RadiusAttack
// "bombsource" is the creature
// that caused the explosion at "bombspot".
//
static BlockItReturn_t PIT_RadiusAttack(mobj_t *thing)
{
	fixed_t dx, dy, dz, dist;

	if (thing == bombspot) // ignore the bomb itself (Deton fix)
		return BMIT_CONTINUE;

	if ((bombdamagetype & DMG_CANTHURTSELF) && bombsource && thing->type == bombsource->type) // ignore the type of guys who dropped the bomb (Jetty-Syn Bomber or Skim can bomb eachother, but not themselves.)
		return BMIT_CONTINUE;

	if ((thing->flags & (MF_MONITOR|MF_SHOOTABLE)) != MF_SHOOTABLE)
		return BMIT_CONTINUE;

	dx = abs(thing->x - bombspot->x);
	dy = abs(thing->y - bombspot->y);
	dz = abs(thing->z + (thing->height>>1) - bombspot->z);

	dist = P_AproxDistance(P_AproxDistance(dx, dy), dz);
	dist -= thing->radius;

	if (dist < 0)
		dist = 0;

	if (dist >= bombdamage)
		return BMIT_CONTINUE; // out of range

	if (thing->floorz > bombspot->z && bombspot->ceilingz < thing->z)
		return BMIT_CONTINUE;

	if (thing->ceilingz < bombspot->z && bombspot->floorz > thing->z)
		return BMIT_CONTINUE;

	if (!bombsightcheck || P_CheckSight(thing, bombspot))
	{	// must be in direct path
		P_DamageMobj(thing, bombspot, bombsource, 1, bombdamagetype); // Tails 01-11-2001
	}

	return BMIT_CONTINUE;
}

//
// P_RadiusAttack
// Source is the creature that caused the explosion at spot.
//
void P_RadiusAttack(mobj_t *spot, mobj_t *source, fixed_t damagedist, UINT8 damagetype, boolean sightcheck)
{
	INT32 x, y;
	INT32 xl, xh, yl, yh;
	fixed_t dist;

	dist = FixedMul(damagedist, spot->scale) + MAXRADIUS;
	yh = (unsigned)(spot->y + dist - bmaporgy)>>MAPBLOCKSHIFT;
	yl = (unsigned)(spot->y - dist - bmaporgy)>>MAPBLOCKSHIFT;
	xh = (unsigned)(spot->x + dist - bmaporgx)>>MAPBLOCKSHIFT;
	xl = (unsigned)(spot->x - dist - bmaporgx)>>MAPBLOCKSHIFT;

	BMBOUNDFIX(xl, xh, yl, yh);

	bombspot = spot;
	bombsource = source;
	bombdamage = FixedMul(damagedist, spot->scale);
	bombdamagetype = damagetype;
	bombsightcheck = sightcheck;

	for (y = yl; y <= yh; y++)
		for (x = xl; x <= xh; x++)
			P_BlockThingsIterator(x, y, PIT_RadiusAttack);
}

//
// SECTOR HEIGHT CHANGING
// After modifying a sectors floor or ceiling height,
// call this routine to adjust the positions
// of all things that touch the sector.
//
// If anything doesn't fit anymore, true will be returned.
// If crunch is true, they will take damage
//  as they are being crushed.
// If Crunch is false, you should set the sector height back
//  the way it was and call P_CheckSector (? was P_ChangeSector - Graue) again
//  to undo the changes.
//
static boolean crushchange;
static boolean nofit;

//
// PIT_ChangeSector
//
static boolean PIT_ChangeSector(mobj_t *thing, boolean realcrush)
{
	mobj_t *killer = NULL;
	//If a thing is both pushable and vulnerable, it doesn't block the crusher because it gets killed.
	boolean immunepushable = ((thing->flags & (MF_PUSHABLE | MF_SHOOTABLE)) == MF_PUSHABLE);

	if (P_ThingHeightClip(thing))
	{
		//thing fits, check next thing
		return true;
	}

	if (!(thing->flags & (MF_SHOOTABLE|MF_PUSHABLE))
	|| thing->flags & MF_NOCLIPHEIGHT)
	{
		//doesn't interact with the crusher, just ignore it
		return true;
	}

	// Thing doesn't fit. If thing is vulnerable, that means it's being crushed. If thing is pushable, it might
	// just be blocked by another object - check if it's really a ceiling!
	if (thing->z + thing->height > thing->ceilingz && thing->z <= thing->ceilingz)
	{
		if (immunepushable && thing->z + thing->height > thing->subsector->sector->ceilingheight)
		{
			//Thing is a pushable and blocks the moving ceiling
			nofit = true;
			return false;
		}

		//Check FOFs in the sector
		if (thing->subsector->sector->ffloors && (realcrush || immunepushable))
		{
			ffloor_t *rover;
			fixed_t topheight, bottomheight;
			fixed_t delta1, delta2;
			INT32 thingtop = thing->z + thing->height;

			for (rover = thing->subsector->sector->ffloors; rover; rover = rover->next)
			{
				if (!(((rover->fofflags & FOF_BLOCKPLAYER) && thing->player)
				|| ((rover->fofflags & FOF_BLOCKOTHERS) && !thing->player)) || !(rover->fofflags & FOF_EXISTS))
					continue;

				topheight = *rover->topheight;
				bottomheight = *rover->bottomheight;
				//topheight    = P_GetFFloorTopZAt   (rover, thing->x, thing->y);
				//bottomheight = P_GetFFloorBottomZAt(rover, thing->x, thing->y);

				delta1 = thing->z - (bottomheight + topheight)/2;
				delta2 = thingtop - (bottomheight + topheight)/2;
				if (bottomheight <= thing->ceilingz && abs(delta1) >= abs(delta2))
				{
					if (immunepushable)
					{
						//FOF is blocked by pushable
						nofit = true;
						return false;
					}
					else
					{
						//If the thing was crushed by a crumbling FOF, reward the player who made it crumble!
						thinker_t *think;
						crumble_t *crumbler;

						for (think = thlist[THINK_MAIN].next; think != &thlist[THINK_MAIN]; think = think->next)
						{
							if (think->function.acp1 != (actionf_p1)T_StartCrumble)
								continue;

							crumbler = (crumble_t *)think;

							if (crumbler->player && crumbler->player->mo
								&& crumbler->player->mo != thing
								&& crumbler->actionsector == thing->subsector->sector
								&& crumbler->sector == rover->master->frontsector)
							{
								killer = crumbler->player->mo;
							}
						}
					}
				}
			}
		}

		if (realcrush)
		{
			// Crush the object
			if (netgame && thing->player && thing->player->spectator)
				P_DamageMobj(thing, NULL, NULL, 1, DMG_SPECTATOR); // Respawn crushed spectators
			else
				P_DamageMobj(thing, killer, killer, 1, DMG_CRUSHED);
			return true;
		}
	}

	if (realcrush && crushchange)
		P_DamageMobj(thing, NULL, NULL, 1, DMG_NORMAL);

	// keep checking (crush other things)
	return true;
}

//
// P_CheckSector
//
boolean P_CheckSector(sector_t *sector, boolean crunch)
{
	msecnode_t *n;
	size_t i;

	nofit = false;
	crushchange = crunch;

	// killough 4/4/98: scan list front-to-back until empty or exhausted,
	// restarting from beginning after each thing is processed. Avoids
	// crashes, and is sure to examine all things in the sector, and only
	// the things which are in the sector, until a steady-state is reached.
	// Things can arbitrarily be inserted and removed and it won't mess up.
	//
	// killough 4/7/98: simplified to avoid using complicated counter


	// First, let's see if anything will keep it from crushing.

	// Sal: This stupid function chain is required to fix polyobjects not being able to crush.
	// Monster Iestyn: don't use P_CheckSector actually just look for objects in the blockmap instead
	validcount++;

	for (i = 0; i < sector->linecount; i++)
	{
		if (sector->lines[i]->polyobj)
		{
			polyobj_t *po = sector->lines[i]->polyobj;
			if (po->validcount == validcount)
				continue; // skip if already checked
			if (!(po->flags & POF_SOLID))
				continue;
			if (po->lines[0]->backsector == sector) // Make sure you're currently checking the control sector
			{
				INT32 x, y;
				po->validcount = validcount;

				for (y = po->blockbox[BOXBOTTOM]; y <= po->blockbox[BOXTOP]; ++y)
				{
					for (x = po->blockbox[BOXLEFT]; x <= po->blockbox[BOXRIGHT]; ++x)
					{
						mobj_t *mo;

						if (x < 0 || y < 0 || x >= bmapwidth || y >= bmapheight)
							continue;

						mo = blocklinks[y * bmapwidth + x];

						for (; mo; mo = mo->bnext)
						{
							// Monster Iestyn: do we need to check if a mobj has already been checked? ...probably not I suspect

							if (!P_MobjInsidePolyobj(po, mo))
								continue;

							if (!PIT_ChangeSector(mo, false))
							{
								nofit = true;
								return nofit;
							}
						}
					}
				}
			}
		}
	}

	if (sector->numattached)
	{
		sector_t *sec;
		for (i = 0; i < sector->numattached; i++)
		{
			sec = &sectors[sector->attached[i]];
			for (n = sec->touching_thinglist; n; n = n->m_thinglist_next)
				n->visited = false;

			sec->moved = true;

			P_RecalcPrecipInSector(sec);

			if (!sector->attachedsolid[i])
				continue;

			do
			{
				for (n = sec->touching_thinglist; n; n = n->m_thinglist_next)
				if (!n->visited)
				{
					n->visited = true;
					if (!(n->m_thing->flags & MF_NOBLOCKMAP))
					{
						if (!PIT_ChangeSector(n->m_thing, false))
						{
							nofit = true;
							return nofit;
						}
					}
					break;
				}
			} while (n);
		}
	}

	// Mark all things invalid
	sector->moved = true;

	for (n = sector->touching_thinglist; n; n = n->m_thinglist_next)
		n->visited = false;

	do
	{
		for (n = sector->touching_thinglist; n; n = n->m_thinglist_next) // go through list
			if (!n->visited) // unprocessed thing found
			{
				n->visited = true; // mark thing as processed
				if (!(n->m_thing->flags & MF_NOBLOCKMAP)) //jff 4/7/98 don't do these
				{
					if (!PIT_ChangeSector(n->m_thing, false)) // process it
					{
						nofit = true;
						return nofit;
					}
				}
				break; // exit and start over
			}
	} while (n); // repeat from scratch until all things left are marked valid

	// Nothing blocked us, so lets crush for real!

	// Sal: This stupid function chain is required to fix polyobjects not being able to crush.
	// Monster Iestyn: don't use P_CheckSector actually just look for objects in the blockmap instead
	validcount++;

	for (i = 0; i < sector->linecount; i++)
	{
		if (sector->lines[i]->polyobj)
		{
			polyobj_t *po = sector->lines[i]->polyobj;
			if (po->validcount == validcount)
				continue; // skip if already checked
			if (!(po->flags & POF_SOLID))
				continue;
			if (po->lines[0]->backsector == sector) // Make sure you're currently checking the control sector
			{
				INT32 x, y;
				po->validcount = validcount;

				for (y = po->blockbox[BOXBOTTOM]; y <= po->blockbox[BOXTOP]; ++y)
				{
					for (x = po->blockbox[BOXLEFT]; x <= po->blockbox[BOXRIGHT]; ++x)
					{
						mobj_t *mo;

						if (x < 0 || y < 0 || x >= bmapwidth || y >= bmapheight)
							continue;

						mo = blocklinks[y * bmapwidth + x];

						for (; mo; mo = mo->bnext)
						{
							// Monster Iestyn: do we need to check if a mobj has already been checked? ...probably not I suspect

							if (!P_MobjInsidePolyobj(po, mo))
								continue;

							PIT_ChangeSector(mo, true);
							return nofit;
						}
					}
				}
			}
		}
	}
	if (sector->numattached)
	{
		sector_t *sec;
		for (i = 0; i < sector->numattached; i++)
		{
			sec = &sectors[sector->attached[i]];
			for (n = sec->touching_thinglist; n; n = n->m_thinglist_next)
				n->visited = false;

			sec->moved = true;

			P_RecalcPrecipInSector(sec);

			if (!sector->attachedsolid[i])
				continue;

			do
			{
				for (n = sec->touching_thinglist; n; n = n->m_thinglist_next)
				if (!n->visited)
				{
					n->visited = true;
					if (!(n->m_thing->flags & MF_NOBLOCKMAP))
					{
						PIT_ChangeSector(n->m_thing, true);
						return nofit;
					}
					break;
				}
			} while (n);
		}
	}

	// Mark all things invalid
	sector->moved = true;

	for (n = sector->touching_thinglist; n; n = n->m_thinglist_next)
		n->visited = false;

	do
	{
		for (n = sector->touching_thinglist; n; n = n->m_thinglist_next) // go through list
			if (!n->visited) // unprocessed thing found
			{
				n->visited = true; // mark thing as processed
				if (!(n->m_thing->flags & MF_NOBLOCKMAP)) //jff 4/7/98 don't do these
				{
					PIT_ChangeSector(n->m_thing, true); // process it
					return nofit;
				}
				break; // exit and start over
			}
	} while (n); // repeat from scratch until all things left are marked valid

	return nofit;
}

/*
 SoM: 3/15/2000
 Lots of new Boom functions that work faster and add functionality.
*/

static msecnode_t *headsecnode = NULL;
static mprecipsecnode_t *headprecipsecnode = NULL;

void P_Initsecnode(void)
{
	headsecnode = NULL;
	headprecipsecnode = NULL;
}

// P_GetSecnode() retrieves a node from the freelist. The calling routine
// should make sure it sets all fields properly.

static msecnode_t *P_GetSecnode(void)
{
	msecnode_t *node;

	if (headsecnode)
	{
		node = headsecnode;
		headsecnode = headsecnode->m_thinglist_next;
	}
	else
		node = Z_Calloc(sizeof (*node), PU_LEVEL, NULL);
	return node;
}

static mprecipsecnode_t *P_GetPrecipSecnode(void)
{
	mprecipsecnode_t *node;

	if (headprecipsecnode)
	{
		node = headprecipsecnode;
		headprecipsecnode = headprecipsecnode->m_thinglist_next;
	}
	else
		node = Z_Calloc(sizeof (*node), PU_LEVEL, NULL);
	return node;
}

// P_PutSecnode() returns a node to the freelist.

static inline void P_PutSecnode(msecnode_t *node)
{
	node->m_thinglist_next = headsecnode;
	headsecnode = node;
}

// Tails 08-25-2002
static inline void P_PutPrecipSecnode(mprecipsecnode_t *node)
{
	node->m_thinglist_next = headprecipsecnode;
	headprecipsecnode = node;
}

// P_AddSecnode() searches the current list to see if this sector is
// already there. If not, it adds a sector node at the head of the list of
// sectors this object appears in. This is called when creating a list of
// nodes that will get linked in later. Returns a pointer to the new node.

static msecnode_t *P_AddSecnode(sector_t *s, mobj_t *thing, msecnode_t *nextnode)
{
	msecnode_t *node;

	node = nextnode;
	while (node)
	{
		if (node->m_sector == s) // Already have a node for this sector?
		{
			node->m_thing = thing; // Yes. Setting m_thing says 'keep it'.
			return nextnode;
		}
		node = node->m_sectorlist_next;
	}

	// Couldn't find an existing node for this sector. Add one at the head
	// of the list.

	node = P_GetSecnode();

	// mark new nodes unvisited.
	node->visited = 0;

	node->m_sector = s; // sector
	node->m_thing = thing; // mobj
	node->m_sectorlist_prev = NULL; // prev node on Thing thread
	node->m_sectorlist_next = nextnode; // next node on Thing thread
	if (nextnode)
		nextnode->m_sectorlist_prev = node; // set back link on Thing

	// Add new node at head of sector thread starting at s->touching_thinglist

	node->m_thinglist_prev = NULL; // prev node on sector thread
	node->m_thinglist_next = s->touching_thinglist; // next node on sector thread
	if (s->touching_thinglist)
		node->m_thinglist_next->m_thinglist_prev = node;
	s->touching_thinglist = node;
	return node;
}

// More crazy crap Tails 08-25-2002
static mprecipsecnode_t *P_AddPrecipSecnode(sector_t *s, precipmobj_t *thing, mprecipsecnode_t *nextnode)
{
	mprecipsecnode_t *node;

	node = nextnode;
	while (node)
	{
		if (node->m_sector == s) // Already have a node for this sector?
		{
			node->m_thing = thing; // Yes. Setting m_thing says 'keep it'.
			return nextnode;
		}
		node = node->m_sectorlist_next;
	}

	// Couldn't find an existing node for this sector. Add one at the head
	// of the list.

	node = P_GetPrecipSecnode();

	// mark new nodes unvisited.
	node->visited = 0;

	node->m_sector = s; // sector
	node->m_thing = thing; // mobj
	node->m_sectorlist_prev = NULL; // prev node on Thing thread
	node->m_sectorlist_next = nextnode; // next node on Thing thread
	if (nextnode)
		nextnode->m_sectorlist_prev = node; // set back link on Thing

	// Add new node at head of sector thread starting at s->touching_thinglist

	node->m_thinglist_prev = NULL; // prev node on sector thread
	node->m_thinglist_next = s->touching_preciplist; // next node on sector thread
	if (s->touching_preciplist)
		node->m_thinglist_next->m_thinglist_prev = node;
	s->touching_preciplist = node;
	return node;
}

// P_DelSecnode() deletes a sector node from the list of
// sectors this object appears in. Returns a pointer to the next node
// on the linked list, or NULL.

static msecnode_t *P_DelSecnode(msecnode_t *node)
{
	msecnode_t *tp; // prev node on thing thread
	msecnode_t *tn; // next node on thing thread
	msecnode_t *sp; // prev node on sector thread
	msecnode_t *sn; // next node on sector thread

	if (!node)
		return NULL;

	// Unlink from the Thing thread. The Thing thread begins at
	// sector_list and not from mobj_t->touching_sectorlist.

	tp = node->m_sectorlist_prev;
	tn = node->m_sectorlist_next;
	if (tp)
		tp->m_sectorlist_next = tn;
	if (tn)
		tn->m_sectorlist_prev = tp;

	// Unlink from the sector thread. This thread begins at
	// sector_t->touching_thinglist.

	sp = node->m_thinglist_prev;
	sn = node->m_thinglist_next;
	if (sp)
		sp->m_thinglist_next = sn;
	else
		node->m_sector->touching_thinglist = sn;
	if (sn)
		sn->m_thinglist_prev = sp;

	// Return this node to the freelist

	P_PutSecnode(node);
	return tn;
}

// Tails 08-25-2002
static mprecipsecnode_t *P_DelPrecipSecnode(mprecipsecnode_t *node)
{
	mprecipsecnode_t *tp; // prev node on thing thread
	mprecipsecnode_t *tn; // next node on thing thread
	mprecipsecnode_t *sp; // prev node on sector thread
	mprecipsecnode_t *sn; // next node on sector thread

	if (!node)
		return NULL;

	// Unlink from the Thing thread. The Thing thread begins at
	// sector_list and not from mobj_t->touching_sectorlist.

	tp = node->m_sectorlist_prev;
	tn = node->m_sectorlist_next;
	if (tp)
		tp->m_sectorlist_next = tn;
	if (tn)
		tn->m_sectorlist_prev = tp;

	// Unlink from the sector thread. This thread begins at
	// sector_t->touching_thinglist.

	sp = node->m_thinglist_prev;
	sn = node->m_thinglist_next;
	if (sp)
		sp->m_thinglist_next = sn;
	else
		node->m_sector->touching_preciplist = sn;
	if (sn)
		sn->m_thinglist_prev = sp;

	// Return this node to the freelist

	P_PutPrecipSecnode(node);
	return tn;
}

// Delete an entire sector list
void P_DelSeclist(msecnode_t *node)
{
	while (node)
		node = P_DelSecnode(node);
}

// Tails 08-25-2002
void P_DelPrecipSeclist(mprecipsecnode_t *node)
{
	while (node)
		node = P_DelPrecipSecnode(node);
}

// PIT_GetSectors
// Locates all the sectors the object is in by looking at the lines that
// cross through it. You have already decided that the object is allowed
// at this location, so don't bother with checking impassable or
// blocking lines.

static inline BlockItReturn_t PIT_GetSectors(line_t *ld)
{
	if (tm.bbox[BOXRIGHT] <= ld->bbox[BOXLEFT] ||
		tm.bbox[BOXLEFT] >= ld->bbox[BOXRIGHT] ||
		tm.bbox[BOXTOP] <= ld->bbox[BOXBOTTOM] ||
		tm.bbox[BOXBOTTOM] >= ld->bbox[BOXTOP])
	return BMIT_CONTINUE;

	if (P_BoxOnLineSide(tm.bbox, ld) != -1)
		return BMIT_CONTINUE;

	if (ld->polyobj) // line belongs to a polyobject, don't add it
		return BMIT_CONTINUE;

	// This line crosses through the object.

	// Collect the sector(s) from the line and add to the
	// sector_list you're examining. If the Thing ends up being
	// allowed to move to this position, then the sector_list
	// will be attached to the Thing's mobj_t at touching_sectorlist.

	sector_list = P_AddSecnode(ld->frontsector,tm.thing,sector_list);

	// Don't assume all lines are 2-sided, since some Things
	// like MT_TFOG are allowed regardless of whether their radius takes
	// them beyond an impassable linedef.

	// Use sidedefs instead of 2s flag to determine two-sidedness.
	if (ld->backsector)
		sector_list = P_AddSecnode(ld->backsector, tm.thing, sector_list);

	return BMIT_CONTINUE;
}

// Tails 08-25-2002
static inline BlockItReturn_t PIT_GetPrecipSectors(line_t *ld)
{
	if (tm.precipbbox[BOXRIGHT] <= ld->bbox[BOXLEFT] ||
		tm.precipbbox[BOXLEFT] >= ld->bbox[BOXRIGHT] ||
		tm.precipbbox[BOXTOP] <= ld->bbox[BOXBOTTOM] ||
		tm.precipbbox[BOXBOTTOM] >= ld->bbox[BOXTOP])
	return BMIT_CONTINUE;

	if (P_BoxOnLineSide(tm.precipbbox, ld) != -1)
		return BMIT_CONTINUE;

	if (ld->polyobj) // line belongs to a polyobject, don't add it
		return BMIT_CONTINUE;

	// This line crosses through the object.

	// Collect the sector(s) from the line and add to the
	// sector_list you're examining. If the Thing ends up being
	// allowed to move to this position, then the sector_list
	// will be attached to the Thing's mobj_t at touching_sectorlist.

	precipsector_list = P_AddPrecipSecnode(ld->frontsector, tm.precipthing, precipsector_list);

	// Don't assume all lines are 2-sided, since some Things
	// like MT_TFOG are allowed regardless of whether their radius takes
	// them beyond an impassable linedef.

	// Use sidedefs instead of 2s flag to determine two-sidedness.
	if (ld->backsector)
		precipsector_list = P_AddPrecipSecnode(ld->backsector, tm.precipthing, precipsector_list);

	return BMIT_CONTINUE;
}

// P_CreateSecNodeList alters/creates the sector_list that shows what sectors
// the object resides in.

void P_CreateSecNodeList(mobj_t *thing, fixed_t x, fixed_t y)
{
	INT32 xl, xh, yl, yh, bx, by;
	msecnode_t *node = sector_list;
	tm_t ptm = tm; /* cph - see comment at func end */

	// First, clear out the existing m_thing fields. As each node is
	// added or verified as needed, m_thing will be set properly. When
	// finished, delete all nodes where m_thing is still NULL. These
	// represent the sectors the Thing has vacated.

	while (node)
	{
		node->m_thing = NULL;
		node = node->m_sectorlist_next;
	}

	P_SetTarget(&tm.thing, thing);
	tm.flags = thing->flags;

	tm.x = x;
	tm.y = y;

	tm.bbox[BOXTOP] = y + tm.thing->radius;
	tm.bbox[BOXBOTTOM] = y - tm.thing->radius;
	tm.bbox[BOXRIGHT] = x + tm.thing->radius;
	tm.bbox[BOXLEFT] = x - tm.thing->radius;

	validcount++; // used to make sure we only process a line once

	xl = (unsigned)(tm.bbox[BOXLEFT] - bmaporgx)>>MAPBLOCKSHIFT;
	xh = (unsigned)(tm.bbox[BOXRIGHT] - bmaporgx)>>MAPBLOCKSHIFT;
	yl = (unsigned)(tm.bbox[BOXBOTTOM] - bmaporgy)>>MAPBLOCKSHIFT;
	yh = (unsigned)(tm.bbox[BOXTOP] - bmaporgy)>>MAPBLOCKSHIFT;

	BMBOUNDFIX(xl, xh, yl, yh);

	for (bx = xl; bx <= xh; bx++)
		for (by = yl; by <= yh; by++)
			P_BlockLinesIterator(bx, by, PIT_GetSectors);

	// Add the sector of the (x, y) point to sector_list.
	sector_list = P_AddSecnode(thing->subsector->sector, thing, sector_list);

	// Now delete any nodes that won't be used. These are the ones where
	// m_thing is still NULL.
	node = sector_list;
	while (node)
	{
		if (!node->m_thing)
		{
			if (node == sector_list)
				sector_list = node->m_sectorlist_next;
			node = P_DelSecnode(node);
		}
		else
			node = node->m_sectorlist_next;
	}

	/* cph -
	* This is the strife we get into for using global variables. tm.thing
	*  is being used by several different functions calling
	*  P_BlockThingIterator, including functions that can be called *from*
	*  P_BlockThingIterator. Using a global tm.thing is not reentrant.
	* OTOH for Boom/MBF demos we have to preserve the buggy behavior.
	*  Fun. We restore its previous value unless we're in a Boom/MBF demo.
	*/
	P_RestoreTMStruct(ptm);
}

// More crazy crap Tails 08-25-2002
void P_CreatePrecipSecNodeList(precipmobj_t *thing,fixed_t x,fixed_t y)
{
	INT32 xl, xh, yl, yh, bx, by;
	mprecipsecnode_t *node = precipsector_list;
	tm_t ptm = tm; /* cph - see comment at func end */

	// First, clear out the existing m_thing fields. As each node is
	// added or verified as needed, m_thing will be set properly. When
	// finished, delete all nodes where m_thing is still NULL. These
	// represent the sectors the Thing has vacated.

	while (node)
	{
		node->m_thing = NULL;
		node = node->m_sectorlist_next;
	}

	tm.precipthing = thing;

	tm.precipbbox[BOXTOP] = y + 2*FRACUNIT;
	tm.precipbbox[BOXBOTTOM] = y - 2*FRACUNIT;
	tm.precipbbox[BOXRIGHT] = x + 2*FRACUNIT;
	tm.precipbbox[BOXLEFT] = x - 2*FRACUNIT;

	validcount++; // used to make sure we only process a line once

	xl = (unsigned)(tm.precipbbox[BOXLEFT] - bmaporgx)>>MAPBLOCKSHIFT;
	xh = (unsigned)(tm.precipbbox[BOXRIGHT] - bmaporgx)>>MAPBLOCKSHIFT;
	yl = (unsigned)(tm.precipbbox[BOXBOTTOM] - bmaporgy)>>MAPBLOCKSHIFT;
	yh = (unsigned)(tm.precipbbox[BOXTOP] - bmaporgy)>>MAPBLOCKSHIFT;

	BMBOUNDFIX(xl, xh, yl, yh);

	for (bx = xl; bx <= xh; bx++)
		for (by = yl; by <= yh; by++)
			P_BlockLinesIterator(bx, by, PIT_GetPrecipSectors);

	// Add the sector of the (x, y) point to sector_list.
	precipsector_list = P_AddPrecipSecnode(thing->subsector->sector, thing, precipsector_list);

	// Now delete any nodes that won't be used. These are the ones where
	// m_thing is still NULL.
	node = precipsector_list;
	while (node)
	{
		if (!node->m_thing)
		{
			if (node == precipsector_list)
				precipsector_list = node->m_sectorlist_next;
			node = P_DelPrecipSecnode(node);
		}
		else
			node = node->m_sectorlist_next;
	}

	/* cph -
	* This is the strife we get into for using global variables. tm.thing
	*  is being used by several different functions calling
	*  P_BlockThingIterator, including functions that can be called *from*
	*  P_BlockThingIterator. Using a global tm.thing is not reentrant.
	* OTOH for Boom/MBF demos we have to preserve the buggy behavior.
	*  Fun. We restore its previous value unless we're in a Boom/MBF demo.
	*/
	P_RestoreTMStruct(ptm);
}

/* cphipps 2004/08/30 -
 * Must clear tm.thing at tic end, as it might contain a pointer to a removed thinker, or the level might have ended/been ended and we clear the objects it was pointing too. Hopefully we don't need to carry this between tics for sync. */
void P_MapStart(void)
{
	if (tm.thing)
		I_Error("P_MapStart: tm.thing set!");
}

void P_MapEnd(void)
{
	P_SetTarget(&tm.thing, NULL);
}

// P_FloorzAtPos
// Returns the floorz of the XYZ position
// Tails 05-26-2003
fixed_t P_FloorzAtPos(fixed_t x, fixed_t y, fixed_t z, fixed_t height)
{
	sector_t *sec = R_PointInSubsector(x, y)->sector;
	fixed_t floorz = P_GetSectorFloorZAt(sec, x, y);

	// Intercept the stupid 'fall through 3dfloors' bug Tails 03-17-2002
	if (sec->ffloors)
	{
		ffloor_t *rover;
		fixed_t delta1, delta2, thingtop = z + height;

		for (rover = sec->ffloors; rover; rover = rover->next)
		{
			fixed_t topheight, bottomheight;
			if (!(rover->fofflags & FOF_EXISTS))
				continue;

			if (!((rover->fofflags & FOF_SOLID) || (rover->fofflags & FOF_QUICKSAND)) || (rover->fofflags & FOF_SWIMMABLE))
				continue;

			topheight    = P_GetFFloorTopZAt   (rover, x, y);
			bottomheight = P_GetFFloorBottomZAt(rover, x, y);

			if (rover->fofflags & FOF_QUICKSAND)
			{
				if (z < topheight && bottomheight < thingtop)
				{
					if (floorz < z)
						floorz = z;
				}
				continue;
			}

			delta1 = z - (bottomheight + ((topheight - bottomheight)/2));
			delta2 = thingtop - (bottomheight + ((topheight - bottomheight)/2));
			if (topheight > floorz && abs(delta1) < abs(delta2))
				floorz = topheight;
		}
	}

	return floorz;
}

// P_CeilingZAtPos
// Returns the ceilingz of the XYZ position
fixed_t P_CeilingzAtPos(fixed_t x, fixed_t y, fixed_t z, fixed_t height)
{
	sector_t *sec = R_PointInSubsector(x, y)->sector;
	fixed_t ceilingz = P_GetSectorCeilingZAt(sec, x, y);

	if (sec->ffloors)
	{
		ffloor_t *rover;
		fixed_t delta1, delta2, thingtop = z + height;

		for (rover = sec->ffloors; rover; rover = rover->next)
		{
			fixed_t topheight, bottomheight;
			if (!(rover->fofflags & FOF_EXISTS))
				continue;

			if ((!(rover->fofflags & FOF_SOLID || rover->fofflags & FOF_QUICKSAND) || (rover->fofflags & FOF_SWIMMABLE)))
				continue;

			topheight    = P_GetFFloorTopZAt   (rover, x, y);
			bottomheight = P_GetFFloorBottomZAt(rover, x, y);

			if (rover->fofflags & FOF_QUICKSAND)
			{
				if (thingtop > bottomheight && topheight > z)
				{
					if (ceilingz > z)
						ceilingz = z;
				}
				continue;
			}

			delta1 = z - (bottomheight + ((topheight - bottomheight)/2));
			delta2 = thingtop - (bottomheight + ((topheight - bottomheight)/2));
			if (bottomheight < ceilingz && abs(delta1) > abs(delta2))
				ceilingz = bottomheight;
		}
	}

	return ceilingz;
}

fixed_t
P_VeryTopOfFOF (ffloor_t *rover)
{
	if (*rover->t_slope)
		return (*rover->t_slope)->highz;
	else
		return *rover->topheight;
}

fixed_t
P_VeryBottomOfFOF (ffloor_t *rover)
{
	if (*rover->b_slope)
		return (*rover->b_slope)->lowz;
	else
		return *rover->bottomheight;
}