Deduplicate a bunch of emerald related code

- Add K_BattleOvertimeKiller
  - Kills an object if it is outside of the Overtime
    Barrier in Battle

- Add Obj_SpawnEmeraldSparks
  - Use this function for MT_EMERALD, MT_MONITOR and
    MT_SPECIAL_UFO

- Move thinking code for MT_EMERALD and MT_MONITOR to
  objects/monitor.c and objects/emerald.c

src/k_battle.c

@@ -853,3 +853,22 @@ INT32 K_BumpersToHealth(UINT8 bumpers)
 {
 	return (bumpers + 1);
 }
+
+boolean K_BattleOvertimeKiller(mobj_t *mobj)
+{
+	if (battleovertime.enabled < 10*TICRATE)
+	{
+		return false;
+	}
+
+	fixed_t distance = R_PointToDist2(mobj->x, mobj->y, battleovertime.x, battleovertime.y);
+
+	if (distance <= battleovertime.radius)
+	{
+		return false;
+	}
+
+	P_KillMobj(mobj, NULL, NULL, DMG_NORMAL);
+
+	return true;
+}

src/k_battle.h

@@ -51,6 +51,7 @@ void K_SpawnPlayerBattleBumpers(player_t *p);
 void K_BattleInit(boolean singleplayercontext);
 UINT8 K_Bumpers(player_t *player);
 INT32 K_BumpersToHealth(UINT8 bumpers);
+boolean K_BattleOvertimeKiller(mobj_t *mobj);
 
 #ifdef __cplusplus
 } // extern "C"

src/k_objects.h

@@ -86,6 +86,7 @@ UINT32 K_GetSpecialUFODistance(void);
 /* Monitors */
 mobj_t *Obj_SpawnMonitor(mobj_t *origin, UINT8 numItemTypes, UINT8 emerald);
 void Obj_MonitorSpawnParts(mobj_t *monitor);
+void Obj_MonitorThink(mobj_t *monitor);
 void Obj_MonitorPartThink(mobj_t *part);
 fixed_t Obj_MonitorGetDamage(mobj_t *monitor, mobj_t *inflictor, UINT8 damagetype);
 void Obj_MonitorOnDamage(mobj_t *monitor, mobj_t *inflictor, INT32 damage);
@@ -201,6 +202,10 @@ void Obj_SneakerPanelSpawn(mobj_t *mobj);
 void Obj_SneakerPanelSetup(mobj_t *mobj, mapthing_t *mthing);
 void Obj_SneakerPanelCollide(mobj_t *pad, mobj_t *mo);
 
+/* Emerald */
+void Obj_SpawnEmeraldSparks(mobj_t *source);
+void Obj_EmeraldThink(mobj_t *emerald);
+
 #ifdef __cplusplus
 } // extern "C"
 #endif

src/objects/CMakeLists.txt

@@ -27,4 +27,5 @@ target_sources(SRB2SDL2 PRIVATE
 	symbol.c
 	dash-rings.c
 	sneaker-panel.c
+	emerald.c
 )

src/objects/battle-ufo.cpp

@@ -137,6 +137,8 @@ void Obj_BattleUFOThink(mobj_t *mobj)
 	{
 		Obj_PointPlayersToXY(mobj->x, mobj->y);
 	}
+
+	K_BattleOvertimeKiller(mobj);
 }
 
 void Obj_BattleUFODeath(mobj_t *mobj)

src/objects/emerald.c

@@ -0,0 +1,39 @@
+#include "../k_battle.h"
+#include "../k_objects.h"
+#include "../info.h"
+#include "../m_random.h"
+#include "../p_local.h"
+
+void Obj_SpawnEmeraldSparks(mobj_t *mobj)
+{
+	if (leveltime % 3 != 0)
+	{
+		return;
+	}
+
+	mobj_t *sparkle = P_SpawnMobjFromMobj(
+		mobj,
+		P_RandomRange(PR_SPARKLE, -48, 48) * FRACUNIT,
+		P_RandomRange(PR_SPARKLE, -48, 48) * FRACUNIT,
+		P_RandomRange(PR_SPARKLE, 0, 64) * FRACUNIT,
+		MT_EMERALDSPARK
+	);
+
+	sparkle->color = mobj->color;
+	sparkle->momz += 8 * mobj->scale * P_MobjFlip(mobj);
+	sparkle->sprzoff = mobj->sprzoff;
+}
+
+void Obj_EmeraldThink(mobj_t *emerald)
+{
+	if (emerald->threshold > 0)
+	{
+		emerald->threshold--;
+	}
+
+	A_AttractChase(emerald);
+
+	Obj_SpawnEmeraldSparks(emerald);
+
+	K_BattleOvertimeKiller(emerald);
+}

src/objects/monitor.c

@@ -495,6 +495,17 @@ Obj_SpawnMonitor
 	return monitor;
 }
 
+void
+Obj_MonitorThink (mobj_t *monitor)
+{
+	if (Obj_MonitorGetEmerald(monitor))
+	{
+		Obj_SpawnEmeraldSparks(monitor);
+	}
+
+	K_BattleOvertimeKiller(monitor);
+}
+
 void
 Obj_MonitorPartThink (mobj_t *part)
 {

src/objects/ufo.c

@@ -467,19 +467,7 @@ static void UFOEmeraldVFX(mobj_t *ufo)
 
 	ufo->sprzoff = FixedMul(bobH, FINESINE(bobA >> ANGLETOFINESHIFT));
 
-	if (leveltime % 3 == 0)
-	{
-		mobj_t *sparkle = P_SpawnMobjFromMobj(
-			ufo,
-			P_RandomRange(PR_SPARKLE, -48, 48) * FRACUNIT,
-			P_RandomRange(PR_SPARKLE, -48, 48) * FRACUNIT,
-			(P_RandomRange(PR_SPARKLE, 0, 64) * FRACUNIT) + FixedDiv(ufo->sprzoff, ufo->scale),
-			MT_EMERALDSPARK
-		);
-
-		sparkle->color = ufo->color;
-		sparkle->momz += 8 * ufo->scale * P_MobjFlip(ufo);
-	}
+	Obj_SpawnEmeraldSparks(ufo);
 }
 
 static boolean UFOHumPlaying(mobj_t *ufo) {

src/p_mobj.c

@@ -7550,48 +7550,19 @@ static boolean P_MobjRegularThink(mobj_t *mobj)
 		break;
 	}
 	case MT_EMERALD:
-		{
-			if (mobj->threshold > 0)
-				mobj->threshold--;
+		Obj_EmeraldThink(mobj);
 
-			A_AttractChase(mobj);
+		if (P_MobjWasRemoved(mobj))
+		{
+			return false;
 		}
-		/*FALLTHRU*/
+		break;
 	case MT_MONITOR:
+		Obj_MonitorThink(mobj);
+
+		if (P_MobjWasRemoved(mobj))
 		{
-			if (battleovertime.enabled >= 10*TICRATE)
-			{
-				fixed_t distance = R_PointToDist2(mobj->x, mobj->y, battleovertime.x, battleovertime.y);
-
-				if (distance > battleovertime.radius)
-				{
-					// Delete emeralds to let them reappear
-					P_KillMobj(mobj, NULL, NULL, DMG_NORMAL);
-					return false;
-				}
-			}
-
-			// Don't spawn sparkles on a monitor with no
-			// emerald inside
-			if (mobj->type == MT_MONITOR &&
-					Obj_MonitorGetEmerald(mobj) == 0)
-			{
-				break;
-			}
-
-			if (leveltime % 3 == 0)
-			{
-				mobj_t *sparkle = P_SpawnMobjFromMobj(
-					mobj,
-					P_RandomRange(PR_SPARKLE, -48, 48) * FRACUNIT,
-					P_RandomRange(PR_SPARKLE, -48, 48) * FRACUNIT,
-					P_RandomRange(PR_SPARKLE, 0, 64) * FRACUNIT,
-					MT_EMERALDSPARK
-				);
-
-				sparkle->color = mobj->color;
-				sparkle->momz += 8 * mobj->scale * P_MobjFlip(mobj);
-			}
+			return false;
 		}
 		break;
 	case MT_DRIFTEXPLODE:
@@ -8466,19 +8437,12 @@ static boolean P_MobjRegularThink(mobj_t *mobj)
 	}
 	case MT_BATTLEUFO:
 	{
-		if (battleovertime.enabled >= 10*TICRATE)
-		{
-			fixed_t distance = R_PointToDist2(mobj->x, mobj->y, battleovertime.x, battleovertime.y);
-
-			if (distance > battleovertime.radius)
-			{
-				// Delete emeralds to let them reappear
-				P_KillMobj(mobj, NULL, NULL, DMG_NORMAL);
-				return false;
-			}
-		}
-
 		Obj_BattleUFOThink(mobj);
+
+		if (P_MobjWasRemoved(mobj))
+		{
+			return false;
+		}
 		break;
 	}
 	case MT_BATTLEUFO_LEG: