Spawn literal MT_EMERALD for UFO Catcher, remove MT_SPECIAL_UFO tracking

Side effects:

- HUD tracking icon now uses emerald's color in Sealed
  Stars.
- UFO emerald doesn't disappear when collected. This is
  WIP because the emerald is intended to orbit the player.

src/k_hud_track.cpp

@@ -8,6 +8,7 @@
 #include "k_hud.h"
 #include "k_kart.h"
 #include "k_objects.h"
+#include "k_specialstage.h"
 #include "m_fixed.h"
 #include "p_local.h"
 #include "p_mobj.h"
@@ -374,9 +375,6 @@ bool is_object_tracking_target(const mobj_t* mobj)
 	case MT_CDUFO:
 		return battleprisons;
 
-	case MT_SPECIAL_UFO:
-		return true;
-
 	case MT_PLAYER:
 		return is_player_tracking_target(mobj->player);
 
@@ -384,7 +382,7 @@ bool is_object_tracking_target(const mobj_t* mobj)
 		return inDuel == false && battleovertime.enabled;
 
 	case MT_EMERALD:
-		return is_player_tracking_target();
+		return specialstageinfo.valid || is_player_tracking_target();
 
 	case MT_MONITOR:
 		return is_player_tracking_target() && Obj_MonitorGetEmerald(mobj) != 0;

src/k_objects.h

@@ -82,6 +82,7 @@ void Obj_UFOPieceDead(mobj_t *piece);
 void Obj_UFOPieceRemoved(mobj_t *piece);
 mobj_t *Obj_CreateSpecialUFO(void);
 UINT32 K_GetSpecialUFODistance(void);
+void Obj_UFOEmeraldThink(mobj_t *emerald);
 
 /* Monitors */
 mobj_t *Obj_SpawnMonitor(mobj_t *origin, UINT8 numItemTypes, UINT8 emerald);

src/objects/emerald.c

@@ -26,6 +26,21 @@ void Obj_SpawnEmeraldSparks(mobj_t *mobj)
 
 void Obj_EmeraldThink(mobj_t *emerald)
 {
+	if (!P_MobjWasRemoved(emerald->target))
+	{
+		switch (emerald->target->type)
+		{
+			case MT_SPECIAL_UFO:
+				Obj_UFOEmeraldThink(emerald);
+				break;
+
+			default:
+				break;
+		}
+
+		return;
+	}
+
 	if (emerald->threshold > 0)
 	{
 		emerald->threshold--;

src/objects/ufo.c

@@ -459,15 +459,15 @@ static void UFOMove(mobj_t *ufo)
 	}
 }
 
-static void UFOEmeraldVFX(mobj_t *ufo)
+static void UFOEmeraldVFX(mobj_t *emerald)
 {
 	const INT32 bobS = 32;
 	const angle_t bobA = (leveltime & (bobS - 1)) * (ANGLE_MAX / bobS);
-	const fixed_t bobH = 16 * ufo->scale;
+	const fixed_t bobH = 16 * emerald->scale;
 
-	ufo->sprzoff = FixedMul(bobH, FINESINE(bobA >> ANGLETOFINESHIFT));
+	emerald->sprzoff = FixedMul(bobH, FINESINE(bobA >> ANGLETOFINESHIFT));
 
-	Obj_SpawnEmeraldSparks(ufo);
+	Obj_SpawnEmeraldSparks(emerald);
 }
 
 static boolean UFOHumPlaying(mobj_t *ufo) {
@@ -504,8 +504,6 @@ void Obj_SpecialUFOThinker(mobj_t *ufo)
 
 	if (UFOEmeraldChase(ufo) == true)
 	{
-		// Spawn emerald sparkles
-		UFOEmeraldVFX(ufo);
 		ufo_collectdelay(ufo)--;
 	}
 	else
@@ -1014,43 +1012,48 @@ static mobj_t *InitSpecialUFO(waypoint_t *start)
 
 	// Adjustable Special Stage emerald color/shape
 	{
-		overlay = P_SpawnMobjFromMobj(ufo, 0, 0, 0, MT_OVERLAY);
+		mobj_t *emerald = P_SpawnMobjFromMobj(ufo, 0, 0, 0, MT_EMERALD);
 
-		ufo->color = SKINCOLOR_CHAOSEMERALD1;
+		emerald->flags |= MF_NOGRAVITY | MF_NOCLIP | MF_NOCLIPTHING | MF_NOCLIPHEIGHT;
+
+		overlay = P_SpawnMobjFromMobj(emerald, 0, 0, 0, MT_OVERLAY);
+
+		emerald->color = SKINCOLOR_CHAOSEMERALD1;
 		i = ufo_emeraldnum(ufo) = P_GetNextEmerald();
 		if (i > 0)
 		{
-			ufo->color += (i - 1) % 7;
+			emerald->color += (i - 1) % 7;
 			if (i > 7)
 			{
 				// Super Emeralds
-				P_SetMobjState(ufo, S_SUPEREMERALD1);
+				P_SetMobjState(emerald, S_SUPEREMERALD1);
 				P_SetMobjState(overlay, S_SUPEREMERALD_UNDER);
 			}
 			else
 			{
 				// Chaos Emerald
-				P_SetMobjState(ufo, S_CHAOSEMERALD1);
+				P_SetMobjState(emerald, S_CHAOSEMERALD1);
 				P_SetMobjState(overlay, S_CHAOSEMERALD_UNDER);
 			}
 		}
 		else
 		{
 			// Prize -- todo, currently using standard Emerald
-			P_SetMobjState(ufo, S_CHAOSEMERALD1);
+			P_SetMobjState(emerald, S_CHAOSEMERALD1);
 			P_SetMobjState(overlay, S_CHAOSEMERALD_UNDER);
 		}
 
-		if (P_MobjWasRemoved(ufo)) // uh oh !
-		{
-			// Attempted crash prevention with custom SOC
-			return NULL;
-		}
+		P_SetTarget(&emerald->target, ufo);
 
-		overlay->color = ufo->color;
-		P_SetTarget(&overlay->target, ufo);
+		ufo->color = emerald->color; // for minimap
+		overlay->color = emerald->color;
 
+		P_SetTarget(&overlay->target, emerald);
+
+		// UFO needs this so Jawz reticle lines up!
 		ufo->sprzoff = 32 * mapobjectscale;
+
+		emerald->sprzoff = ufo->sprzoff;
 	}
 
 	// Create UFO pieces.
@@ -1172,3 +1175,16 @@ UINT32 K_GetSpecialUFODistance(void)
 
 	return UINT32_MAX;
 }
+
+void Obj_UFOEmeraldThink(mobj_t *emerald)
+{
+	mobj_t *ufo = emerald->target;
+
+	P_MoveOrigin(emerald, ufo->x, ufo->y, ufo->z);
+
+	if (UFOEmeraldChase(ufo) == true)
+	{
+		// Spawn emerald sparkles
+		UFOEmeraldVFX(emerald);
+	}
+}

src/p_mobj.c

@@ -5325,7 +5325,6 @@ static boolean P_IsTrackerType(INT32 type)
 		case MT_SPB:
 		case MT_BATTLECAPSULE:
 		case MT_CDUFO:
-		case MT_SPECIAL_UFO:
 			return true;
 
 		// Players sometimes get targeted with HUD tracking