Add "twinkle" lens flare to emeralds

- Battle: plays once the orbiting collection animation
  finishes and the player's emerald flags are updated
  - Centered on the player

- Sealed Star: plays as soon as the orbiting animation
  begins
  - Centered on the emerald

src/deh_tables.c

@@ -1208,6 +1208,8 @@ const char *const STATE_LIST[] = { // array length left dynamic for sanity testi
 	"S_EMERALDSPARK6",
 	"S_EMERALDSPARK7",
 
+	"S_EMERALDFLARE1",
+
 	// Emerald hunt shards
 	"S_SHRD1",
 	"S_SHRD2",
@@ -4807,6 +4809,7 @@ const char *const MOBJTYPE_LIST[] = {  // array length left dynamic for sanity t
 	"MT_EMBLEM",
 	"MT_EMERALD",
 	"MT_EMERALDSPARK",
+	"MT_EMERALDFLARE",
 	"MT_EMERHUNT", // Emerald Hunt
 	"MT_EMERALDSPAWN", // Emerald spawner w/ delay
 

src/info.c

@@ -1878,6 +1878,8 @@ state_t states[NUMSTATES] =
 	{SPR_ESPK, FF_FULLBRIGHT|5, 3, {NULL}, 0, 0, S_EMERALDSPARK7}, // S_EMERALDSPARK6
 	{SPR_ESPK, FF_FULLBRIGHT|6, 3, {NULL}, 0, 0, S_NULL}, // S_EMERALDSPARK7
 
+	{SPR_LENS, FF_FULLBRIGHT|FF_ADD|FF_TRANS10|FF_ANIMATE|11, 8, {NULL}, 7, 1, S_GAINAX_MID2}, // S_EMERALDFLARE1
+
 	// Emerald hunt shards
 	{SPR_SHRD, 0, -1, {NULL}, 0, 0, S_NULL}, // S_SHRD1
 	{SPR_SHRD, 1, -1, {NULL}, 0, 0, S_NULL}, // S_SHRD2
@@ -8330,6 +8332,33 @@ mobjinfo_t mobjinfo[NUMMOBJTYPES] =
 		S_NULL          // raisestate
 	},
 
+	{           // MT_EMERALDFLARE
+		-1,             // doomednum
+		S_INVISIBLE,    // spawnstate
+		1000,           // spawnhealth
+		S_NULL,         // seestate
+		sfx_None,       // seesound
+		8,              // reactiontime
+		sfx_None,       // attacksound
+		S_NULL,         // painstate
+		0,              // painchance
+		sfx_None,       // painsound
+		S_NULL,         // meleestate
+		S_NULL,         // missilestate
+		S_NULL,         // deathstate
+		S_NULL,         // xdeathstate
+		sfx_None,       // deathsound
+		0,              // speed
+		8*FRACUNIT,     // radius
+		8*FRACUNIT,     // height
+		0,              // display offset
+		16,             // mass
+		0,              // damage
+		sfx_None,       // activesound
+		MF_NOBLOCKMAP|MF_NOGRAVITY|MF_NOCLIP|MF_NOCLIPHEIGHT|MF_DONTENCOREMAP, // flags
+		S_NULL          // raisestate
+	},
+
 	{           // MT_EMERHUNT
 		320,            // doomednum
 		S_SHRD1,        // spawnstate

src/info.h

@@ -2362,6 +2362,8 @@ typedef enum state
 	S_EMERALDSPARK6,
 	S_EMERALDSPARK7,
 
+	S_EMERALDFLARE1,
+
 	// Emerald hunt shards
 	S_SHRD1,
 	S_SHRD2,
@@ -5996,6 +5998,7 @@ typedef enum mobj_type
 	MT_EMBLEM,
 	MT_EMERALD,
 	MT_EMERALDSPARK,
+	MT_EMERALDFLARE,
 	MT_EMERHUNT, // Emerald Hunt
 	MT_EMERALDSPAWN, // Emerald spawner w/ delay
 

src/k_objects.h

@@ -207,6 +207,7 @@ void Obj_SneakerPanelCollide(mobj_t *pad, mobj_t *mo);
 /* Emerald */
 void Obj_SpawnEmeraldSparks(mobj_t *source);
 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);
 

src/objects/emerald.c

@@ -1,5 +1,6 @@
 #include "../k_battle.h"
 #include "../k_objects.h"
+#include "../k_specialstage.h"
 #include "../info.h"
 #include "../m_random.h"
 #include "../p_local.h"
@@ -163,6 +164,70 @@ void Obj_EmeraldThink(mobj_t *emerald)
 	K_BattleOvertimeKiller(emerald);
 }
 
+void Obj_EmeraldFlareThink(mobj_t *flare)
+{
+	const INT32 kExtraTics = 3;
+	const INT32 flare_tics = states[S_EMERALDFLARE1].tics + kExtraTics;
+
+	if (P_MobjWasRemoved(flare->target))
+	{
+		P_RemoveMobj(flare);
+		return;
+	}
+
+	// Target is assumed to be the emerald in orbit. When
+	// emerald fuse runs out, it shall update player's emerald
+	// flags. Time the flare animation so it ends with the
+	// emerald fuse.
+	if (!flare->fuse && flare->target->fuse > flare_tics)
+	{
+		return;
+	}
+
+	if (flare->state == &states[S_INVISIBLE])
+	{
+		// In special stages, just follow the emerald.
+		if (specialstageinfo.valid == false)
+		{
+			// Update target to player. We don't need to track
+			// the emerald anymore.
+			P_SetTarget(&flare->target, flare->target->target);
+
+			if (P_MobjWasRemoved(flare->target))
+			{
+				P_RemoveMobj(flare);
+				return;
+			}
+		}
+
+		P_SetMobjState(flare, S_EMERALDFLARE1);
+		flare->fuse = flare_tics;
+	}
+
+	// Focus on center of player.
+	P_SetOrigin(flare, flare->target->x, flare->target->y, center_of(flare->target));
+}
+
+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);
+
+	flare->color = emerald->color;
+	flare->colorized = true;
+
+	flare->renderflags |= RF_ALWAYSONTOP;
+
+	// 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);
+	flare->flags2 |= MF2_LINKDRAW;
+	flare->dispoffset = 1000;
+#endif
+}
+
 void Obj_BeginEmeraldOrbit(mobj_t *emerald, mobj_t *target, fixed_t radius, INT32 revolution_time, tic_t fuse)
 {
 	P_SetTarget(&emerald->target, target);
@@ -185,6 +250,8 @@ void Obj_BeginEmeraldOrbit(mobj_t *emerald, mobj_t *target, fixed_t radius, INT3
 
 	emerald->flags |= MF_NOGRAVITY | MF_NOCLIP | MF_NOCLIPTHING | MF_NOCLIPHEIGHT;
 	emerald->shadowscale = 0;
+
+	spawn_lens_flare(emerald);
 }
 
 void Obj_GiveEmerald(mobj_t *emerald)

src/p_mobj.c

@@ -7551,6 +7551,14 @@ static boolean P_MobjRegularThink(mobj_t *mobj)
 	case MT_EMERALD:
 		Obj_EmeraldThink(mobj);
 
+		if (P_MobjWasRemoved(mobj))
+		{
+			return false;
+		}
+		break;
+	case MT_EMERALDFLARE:
+		Obj_EmeraldFlareThink(mobj);
+
 		if (P_MobjWasRemoved(mobj))
 		{
 			return false;