Add basic Battle UFO object functionality

src/k_objects.h

@@ -161,6 +161,12 @@ void Obj_SuperFlickyPlayerCollide(mobj_t *flicky, mobj_t *player);
 void Obj_SuperFlickyLanding(mobj_t *flicky);
 boolean Obj_IsSuperFlickyWhippable(const mobj_t *flicky);
 
+/* Battle/Power-UP UFO */
+void Obj_BattleUFOLegThink(mobj_t *leg);
+void Obj_BattleUFOThink(mobj_t *ufo);
+void Obj_SpawnBattleUFOLegs(mobj_t *ufo);
+void Obj_BattleUFODeath(mobj_t *ufo);
+
 /* Power-Up Aura */
 void Obj_SpawnPowerUpAura(player_t* player);
 void Obj_PowerUpAuraThink(mobj_t* mobj);

src/objects/CMakeLists.txt

@@ -22,5 +22,6 @@ target_sources(SRB2SDL2 PRIVATE
 	gachabom-rebound.cpp
 	servant-hand.c
 	super-flicky.cpp
+	battle-ufo.c
 	powerup-aura.cpp
 )

src/objects/battle-ufo.c

@@ -0,0 +1,68 @@
+#include "../doomdef.h"
+#include "../p_local.h"
+#include "../k_objects.h"
+
+#define BATTLEUFO_LEG_ZOFFS (3*FRACUNIT) // Spawn height offset from the body
+#define BATTLEUFO_LEGS (3) // Number of UFO legs to spawn
+#define BATTLEUFO_BOB_AMP (4) // UFO bob strength
+#define BATTLEUFO_BOB_SPEED (TICRATE*2) // UFO bob speed
+
+void Obj_BattleUFOThink(mobj_t *ufo)
+{
+	// Copied and slightly modified from k_kart.c
+	fixed_t sine = FixedMul(ufo->scale, BATTLEUFO_BOB_AMP * FINESINE((((M_TAU_FIXED * BATTLEUFO_BOB_SPEED) * leveltime) >> ANGLETOFINESHIFT) & FINEMASK));
+	fixed_t targz = FixedMul(ufo->scale, sine) * P_MobjFlip(ufo);
+	ufo->momz = targz;
+}
+
+void Obj_BattleUFODeath(mobj_t *ufo)
+{
+	ufo->momz = -(8*mapobjectscale)/2;
+	ufo->fuse = TICRATE;
+}
+
+void Obj_SpawnBattleUFOLegs(mobj_t *ufo)
+{
+	INT32 i;
+	angle_t ang = 0;
+	const fixed_t angle_factor = ANGLE_MAX / BATTLEUFO_LEGS;
+
+	for (i = 0; i < BATTLEUFO_LEGS; i++)
+	{
+		mobj_t *leg = P_SpawnMobjFromMobj(ufo, 0, 0, BATTLEUFO_LEG_ZOFFS, MT_BATTLEUFO_LEG);
+		P_SetTarget(&leg->target, ufo);
+		ang += angle_factor;
+		leg->angle = ang;
+	}
+}
+
+void Obj_BattleUFOLegThink(mobj_t *leg)
+{
+	if (!leg->target || P_MobjWasRemoved(leg->target))
+	{
+		P_RemoveMobj(leg);
+		return;
+	}
+
+	// Rotate around the UFO
+	if (leg->target->health > 0)
+	{
+		leg->angle += FixedAngle(leg->info->speed);
+
+		const angle_t fa = leg->angle>>ANGLETOFINESHIFT;
+		const fixed_t radius = FixedMul(14*leg->info->speed, leg->target->scale);
+		fixed_t x = leg->target->x + FixedMul(FINECOSINE(fa),radius);
+		fixed_t y = leg->target->y + FixedMul(FINESINE(fa),radius);
+
+		// TODO: Take gravflip into account
+		P_MoveOrigin(leg, x, y, leg->z);
+	}
+
+	leg->momz = leg->target->momz;
+
+	if (leg->target->hitlag)
+	{
+		leg->hitlag = leg->target->hitlag;
+		leg->eflags |= (leg->target->eflags & MFE_DAMAGEHITLAG);
+	}
+}

src/p_inter.c

@@ -799,7 +799,7 @@ void P_CheckTimeLimit(void)
 			{
 				if (((timelimitintics + starttime - leveltime) % TICRATE) == 0)
 					S_StartSound(NULL, sfx_s3ka7);
-			}			
+			}
 		}
 		return;
 	}
@@ -1725,7 +1725,9 @@ void P_KillMobj(mobj_t *target, mobj_t *inflictor, mobj_t *source, UINT8 damaget
 		case MT_MONITOR:
 			Obj_MonitorOnDeath(target);
 			break;
-
+		case MT_BATTLEUFO:
+			Obj_BattleUFODeath(target);
+			break;
 		default:
 			break;
 	}

src/p_mobj.c

@@ -8069,7 +8069,7 @@ static boolean P_MobjRegularThink(mobj_t *mobj)
 		// cusval: responsible for disappear FX (should only happen once)
 
 		// S_MAGICANBOX: sides, starting angle is set in the spawner (SetRandomFakePlayerSkin)
-		// S_MAGICIANBOX_TOP, S_MAGICIANBOX_BOTTOM: splats with their own offset sprite sets  
+		// S_MAGICIANBOX_TOP, S_MAGICIANBOX_BOTTOM: splats with their own offset sprite sets
 
 		mobj->extravalue2--;
 
@@ -8436,6 +8436,16 @@ static boolean P_MobjRegularThink(mobj_t *mobj)
 		Obj_ItemDebrisThink(mobj);
 		break;
 	}
+	case MT_BATTLEUFO:
+	{
+		Obj_BattleUFOThink(mobj);
+		break;
+	}
+	case MT_BATTLEUFO_LEG:
+	{
+		Obj_BattleUFOLegThink(mobj);
+		break;
+	}
 	case MT_ROCKETSNEAKER:
 		if (!mobj->target || !mobj->target->health)
 		{
@@ -10920,6 +10930,9 @@ mobj_t *P_SpawnMobj(fixed_t x, fixed_t y, fixed_t z, mobjtype_t type)
 		case MT_SPHEREBOX:
 			Obj_RandomItemSpawn(mobj);
 			break;
+		case MT_BATTLEUFO:
+			Obj_SpawnBattleUFOLegs(mobj);
+			break;
 		default:
 			break;
 	}
@@ -12268,7 +12281,7 @@ static mobjtype_t P_GetMobjtypeSubstitute(mapthing_t *mthing, mobjtype_t i)
 
 	if ((i == MT_RANDOMITEM) && (gametyperules & (GTR_PAPERITEMS|GTR_CIRCUIT)) == (GTR_PAPERITEMS|GTR_CIRCUIT))
 		return MT_PAPERITEMSPOT;
-	
+
 	return i;
 }