TRIPWIRE

Set a sidedef's midtexture to "TRIPWIRE" to turn that line
into a tripwire.

Players can't drive through a tripwire and will bounce
back at high speed if they're in one of the following
states:

1. Invincibility / Grow
2. Sneakers
3. Flame Shield dash
4. >200% on the speedometer

Hitting a tripwire plays a sound, sends you into hitlag,
then plays another sound when the hitlag is over. The
sounds used depend on whether you can drive through the
tripwire.

src/d_player.h

@@ -198,6 +198,13 @@ typedef enum
 #undef KSPIN_TYPE
 } kartspinoutflags_t;
 
+typedef enum
+{
+	TRIP_NONE,
+	TRIP_PASSED,
+	TRIP_BLOCKED,
+} tripwirestate_t;
+
 typedef enum
 {
 	// Unsynced, HUD or clientsided effects
@@ -470,6 +477,8 @@ typedef struct player_s
 
 	SINT8 glanceDir; // Direction the player is trying to look backwards in
 
+	UINT8 tripWireState; // see tripwirestate_t
+
 	//
 
 	SINT8 lives;

src/g_game.c

@@ -2287,6 +2287,7 @@ void G_PlayerReborn(INT32 player, boolean betweenmaps)
 	p->karthud[khud_fault] = khudfault;
 	p->nocontrol = nocontrol;
 	p->kickstartaccel = kickstartaccel;
+	p->tripWireState = TRIP_NONE;
 
 	memcpy(&p->respawn, &respawn, sizeof (p->respawn));
 

src/k_kart.c

@@ -2673,6 +2673,19 @@ boolean K_SlopeResistance(player_t *player)
 	return false;
 }
 
+boolean K_TripwirePass(player_t *player)
+{
+	if (
+			player->invincibilitytimer ||
+			player->sneakertimer ||
+			player->growshrinktimer > 0 ||
+			player->flamedash ||
+			player->speed > 2 * K_GetKartSpeed(player, false)
+	)
+		return true;
+	return false;
+}
+
 static fixed_t K_FlameShieldDashVar(INT32 val)
 {
 	// 1 second = 75% + 50% top speed
@@ -3300,6 +3313,17 @@ static void K_HandleTumbleSound(player_t *player)
 	}
 }
 
+void K_ApplyTripWire(player_t *player, tripwirestate_t state)
+{
+	if (state == TRIP_PASSED)
+		S_StartSound(player->mo, sfx_ssa015);
+	else if (state == TRIP_BLOCKED)
+		S_StartSound(player->mo, sfx_kc40);
+
+	player->tripWireState = state;
+	K_AddHitLag(player->mo, 10, false);
+}
+
 INT32 K_ExplodePlayer(player_t *player, mobj_t *inflictor, mobj_t *source) // A bit of a hack, we just throw the player up higher here and extend their spinout timer
 {
 	INT32 ringburst = 10;
@@ -6983,6 +7007,16 @@ void K_KartPlayerThink(player_t *player, ticcmd_t *cmd)
 
 	// Handle invincibility sfx
 	K_UpdateInvincibilitySounds(player); // Also thanks, VAda!
+
+	if (player->tripWireState != TRIP_NONE)
+	{
+		if (player->tripWireState == TRIP_PASSED)
+			S_StartSound(player->mo, sfx_cdfm63);
+		else if (player->tripWireState == TRIP_BLOCKED)
+			S_StartSound(player->mo, sfx_kc4c);
+
+		player->tripWireState = TRIP_NONE;
+	}
 }
 
 void K_KartPlayerAfterThink(player_t *player)

src/k_kart.h

@@ -105,6 +105,8 @@ void K_StripOther(player_t *player);
 void K_MomentumToFacing(player_t *player);
 boolean K_ApplyOffroad(player_t *player);
 boolean K_SlopeResistance(player_t *player);
+boolean K_TripwirePass(player_t *player);
+void K_ApplyTripWire(player_t *player, tripwirestate_t state);
 INT16 K_GetSpindashChargeTime(player_t *player);
 fixed_t K_GetSpindashChargeSpeed(player_t *player);
 fixed_t K_GetKartSpeedFromStat(UINT8 kartspeed);

src/p_local.h

@@ -398,6 +398,7 @@ void P_SetThingPosition(mobj_t *thing);
 void P_SetUnderlayPosition(mobj_t *thing);
 
 boolean P_IsLineBlocking(const line_t *ld, const mobj_t *thing);
+boolean P_IsLineTripWire(const line_t *ld);
 boolean P_CheckPosition(mobj_t *thing, fixed_t x, fixed_t y);
 boolean P_CheckCameraPosition(fixed_t x, fixed_t y, camera_t *thiscam);
 boolean P_TryMove(mobj_t *thing, fixed_t x, fixed_t y, boolean allowdropoff);

src/p_map.c

@@ -1552,6 +1552,12 @@ boolean P_IsLineBlocking(const line_t *ld, const mobj_t *thing)
 	}
 }
 
+boolean P_IsLineTripWire(const line_t *ld)
+{
+	return (sides[ld->sidenum[0]].midtexture ==
+			R_TextureNumForName("TRIPWIRE"));
+}
+
 //
 // PIT_CheckLine
 // Adjusts tmfloorz and tmceilingz as lines are contacted
@@ -1666,7 +1672,8 @@ static boolean PIT_CheckLine(line_t *ld)
 		tmdropoffz = lowfloor;
 
 	// we've crossed the line
-	if (P_SpecialIsLinedefCrossType(ld->special))
+	if (P_SpecialIsLinedefCrossType(ld->special) ||
+			P_IsLineTripWire(ld))
 	{
 		add_spechit(ld);
 	}
@@ -3022,6 +3029,7 @@ 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 = R_PointToAngle2(0, 0, ld->dx, ld->dy)-ANGLE_90;
@@ -3036,8 +3044,19 @@ static void P_PlayerHitBounceLine(line_t *ld)
 	if (slidemo->player && movelen < (15*mapobjectscale))
 		movelen = (15*mapobjectscale);
 
-	tmxmove += FixedMul(movelen, FINECOSINE(lineangle));
-	tmymove += FixedMul(movelen, FINESINE(lineangle));
+	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;
+	}
 }
 
 //
@@ -3675,6 +3694,11 @@ void P_BouncePlayerMove(mobj_t *mo)
 		tmymove = FixedMul(mmomy, (FRACUNIT - (FRACUNIT>>2) - (FRACUNIT>>3)));
 	}
 
+	if (P_IsLineTripWire(bestslideline))
+	{
+		K_ApplyTripWire(mo->player, TRIP_BLOCKED);
+	}
+	else
 	{
 		mobj_t *fx = P_SpawnMobj(mo->x, mo->y, mo->z, MT_BUMP);
 		if (mo->eflags & MFE_VERTICALFLIP)
@@ -3694,8 +3718,11 @@ void P_BouncePlayerMove(mobj_t *mo)
 	mo->player->cmomx = tmxmove;
 	mo->player->cmomy = tmymove;
 
-	if (!P_TryMove(mo, mo->x + tmxmove, mo->y + tmymove, true)) {
-		P_TryMove(mo, mo->x - oldmomx, mo->y - oldmomy, true);
+	if (!P_IsLineTripWire(bestslideline))
+	{
+		if (!P_TryMove(mo, mo->x + tmxmove, mo->y + tmymove, true)) {
+			P_TryMove(mo, mo->x - oldmomx, mo->y - oldmomy, true);
+		}
 	}
 }
 

src/p_maputl.c

@@ -15,6 +15,7 @@
 #include "doomdef.h"
 #include "doomstat.h"
 
+#include "k_kart.h"
 #include "p_local.h"
 #include "r_main.h"
 #include "r_data.h"
@@ -588,7 +589,7 @@ void P_LineOpening(line_t *linedef, mobj_t *mobj)
 	if (mobj)
 	{
 		// Check for collision with front side's midtexture if Effect 4 is set
-		if (linedef->flags & ML_EFFECT4
+		if ((linedef->flags & ML_EFFECT4 || (mobj->player && P_IsLineTripWire(linedef) && !K_TripwirePass(mobj->player)))
 			&& !linedef->polyobj // don't do anything for polyobjects! ...for now
 			) {
 			side_t *side = &sides[linedef->sidenum[0]];

src/p_saveg.c

@@ -318,6 +318,7 @@ static void P_NetArchivePlayers(void)
 		WRITEINT16(save_p, players[i].spheres);
 
 		WRITESINT8(save_p, players[i].glanceDir);
+		WRITEUINT8(save_p, players[i].tripWireState);
 
 		WRITEUINT8(save_p, players[i].typing_timer);
 		WRITEUINT8(save_p, players[i].typing_duration);
@@ -573,6 +574,7 @@ static void P_NetUnArchivePlayers(void)
 		players[i].spheres = READINT16(save_p);
 
 		players[i].glanceDir = READSINT8(save_p);
+		players[i].tripWireState = READUINT8(save_p);
 
 		players[i].typing_timer = READUINT8(save_p);
 		players[i].typing_duration = READUINT8(save_p);

src/p_spec.c

@@ -2018,6 +2018,13 @@ void P_CrossSpecialLine(line_t *line, INT32 side, mobj_t *thing)
 		return;
 	{
 		player_t *player = thing->player;
+
+		if (P_IsLineTripWire(line))
+		{
+			K_ApplyTripWire(player, TRIP_PASSED);
+			return;
+		}
+
 		switch (line->special)
 		{
 			case 2001: // Finish Line