MT_EMERALD: prepartion to let orbiting physics be used in a general-purpose manner

- Add Obj_SetEmeraldAwardee
  - Separate object receiving emerald from object being
    orbited
  - Obj_BeginEmeraldOrbit sets both, if the awardee isn't
    explicitly set
- Don't HUD track emeralds without emerald flag set

src/k_hud_track.cpp

@@ -448,7 +448,8 @@ bool is_object_tracking_target(const mobj_t* mobj)
 		return inDuel == false && battleovertime.enabled;
 
 	case MT_EMERALD:
-		return (specialstageinfo.valid && specialstageinfo.ufo) || is_player_tracking_target();
+		// extravalue1: emerald flag must be set
+		return mobj->extravalue1 && ((specialstageinfo.valid && specialstageinfo.ufo) || is_player_tracking_target());
 
 	case MT_MONITOR:
 		return is_player_tracking_target() && Obj_MonitorGetEmerald(mobj) != 0;

src/k_objects.h

@@ -213,6 +213,7 @@ void Obj_EmeraldThink(mobj_t *emerald);
 void Obj_EmeraldFlareThink(mobj_t *flare);
 void Obj_BeginEmeraldOrbit(mobj_t *emerald, mobj_t *target, fixed_t radius, INT32 revolution_time, tic_t fuse);
 void Obj_GiveEmerald(mobj_t *emerald);
+void Obj_SetEmeraldAwardee(mobj_t *emerald, mobj_t *awardee);
 
 /* Fake Shadow */
 mobj_t *Obj_SpawnFakeShadow(mobj_t *from);

src/objects/emerald.c

@@ -15,6 +15,8 @@
 #define emerald_target_radius(o) ((o)->extravalue2)
 #define emerald_z_shift(o) ((o)->reactiontime)
 #define emerald_scale_rate(o) ((o)->movefactor)
+#define emerald_orbit(o) ((o)->target)
+#define emerald_award(o) ((o)->tracer)
 
 // Think of this like EMERALD_SPEED_UP / EMERALD_SPEED_UP_RATE
 #define EMERALD_SPEED_UP (1) // speed up by this much...
@@ -84,7 +86,7 @@ static fixed_t get_target_z(mobj_t *emerald)
 {
 	fixed_t shift = FixedMul(emerald_z_shift(emerald), FRACUNIT - get_suck_factor(emerald));
 
-	return center_of(emerald->target) + get_bob(emerald) + shift;
+	return center_of(emerald_orbit(emerald)) + get_bob(emerald) + shift;
 }
 
 static void speed_up(mobj_t *emerald)
@@ -116,8 +118,8 @@ static void Obj_EmeraldOrbitPlayer(mobj_t *emerald)
 
 	P_MoveOrigin(
 			emerald,
-			emerald->target->x + x,
+			emerald_orbit(emerald)->x + x,
-			emerald->target->y + y,
+			emerald_orbit(emerald)->y + y,
 			get_target_z(emerald)
 	);
 
@@ -133,9 +135,9 @@ static void Obj_EmeraldOrbitPlayer(mobj_t *emerald)
 
 void Obj_EmeraldThink(mobj_t *emerald)
 {
-	if (!P_MobjWasRemoved(emerald->target))
+	if (!P_MobjWasRemoved(emerald_orbit(emerald)))
 	{
-		switch (emerald->target->type)
+		switch (emerald_orbit(emerald)->type)
 		{
 			case MT_SPECIAL_UFO:
 				Obj_UFOEmeraldThink(emerald);
@@ -256,7 +258,7 @@ static void spawn_lens_flare(mobj_t *emerald)
 	mobj_t *flare = P_SpawnMobjFromMobj(emerald, 0, 0, 0, MT_EMERALDFLARE);
 
 	P_SetTarget(&flare->target, emerald);
-	P_InstaScale(flare, emerald->target->scale);
+	P_InstaScale(flare, emerald_orbit(emerald)->scale);
 
 	flare->color = emerald->color;
 	flare->colorized = true;
@@ -265,7 +267,7 @@ static void spawn_lens_flare(mobj_t *emerald)
 
 	// FIXME: linkdraw doesn't work consistently, so I drew it on top of everyting (and through walls)
 #if 0
-	P_SetTarget(&flare->tracer, emerald->target);
+	P_SetTarget(&flare->tracer, emerald_orbit(emerald));
 	flare->flags2 |= MF2_LINKDRAW;
 	flare->dispoffset = 1000;
 #endif
@@ -273,7 +275,12 @@ static void spawn_lens_flare(mobj_t *emerald)
 
 void Obj_BeginEmeraldOrbit(mobj_t *emerald, mobj_t *target, fixed_t radius, INT32 revolution_time, tic_t fuse)
 {
-	P_SetTarget(&emerald->target, target);
+	P_SetTarget(&emerald_orbit(emerald), target);
+
+	if (P_MobjWasRemoved(emerald_award(emerald)))
+	{
+		P_SetTarget(&emerald_award(emerald), target);
+	}
 
 	emerald_anim_start(emerald) = leveltime;
 	emerald_revolution_time(emerald) = revolution_time;
@@ -299,12 +306,12 @@ void Obj_BeginEmeraldOrbit(mobj_t *emerald, mobj_t *target, fixed_t radius, INT3
 
 void Obj_GiveEmerald(mobj_t *emerald)
 {
-	if (P_MobjWasRemoved(emerald->target))
+	if (P_MobjWasRemoved(emerald_orbit(emerald)) || P_MobjWasRemoved(emerald_award(emerald)))
 	{
 		return;
 	}
 
-	player_t *player = emerald->target->player;
+	player_t *player = emerald_award(emerald)->player;
 
 	if (!player)
 	{
@@ -314,5 +321,10 @@ void Obj_GiveEmerald(mobj_t *emerald)
 	player->emeralds |= emerald_type(emerald);
 	K_CheckEmeralds(player);
 
-	S_StartSound(emerald->target, emerald->info->deathsound);
+	S_StartSound(emerald_award(emerald), emerald->info->deathsound);
+}
+
+void Obj_SetEmeraldAwardee(mobj_t *emerald, mobj_t *awardee)
+{
+	P_SetTarget(&emerald_award(emerald), awardee);
 }