Document some stuff with Entrance lightning (#1745)

Mostly just some light renaming.

I used my new entity animation viewer to figure out what this function
was, it's a very subtle cloud effect that would have been hard to
identify otherwise.

The driving factor for this was removing ext.generic from this entity,
which is also complete.

This applies to both NO3 and NP3.

config/symbols.us.stno3.txt

@@ -49,7 +49,7 @@ EntityStairwayPiece = 0x801BAEF0;
 EntityFallingRock = 0x801BB3BC;
 EntityDeathSkySwirl = 0x801BBB8C;
 EntityLightningThunder = 0x801BBDC0;
-EntityUnkId2A = 0x801BBE70;
+EntityLightningCloud = 0x801BBE70;
 EntitySwitch = 0x801BBF38;
 EntityHeartRoomGoldDoor = 0x801BC05C;
 EntityUnkId49 = 0x801BC3FC;

src/st/no3/377D4.c

@@ -188,7 +188,7 @@ void EntityBackgroundLightning(Entity* self) {
             }
             otherEnt = AllocEntity(&g_Entities[224], &g_Entities[256]);
             if (otherEnt != NULL) {
-                CreateEntityFromCurrentEntity(E_ID_2A, otherEnt);
+                CreateEntityFromCurrentEntity(E_LIGHTNING_CLOUD, otherEnt);
                 if (randOf3 > 2) {
                     randOf3 = 0;
                 }
@@ -1905,19 +1905,22 @@ void EntityLightningThunder(Entity* self) {
     }
 }
 
-void EntityUnkId2A(Entity* entity) {
-    if (entity->step == 0) {
+// When lightning strikes, we get a bright bolt, but it is against a cloud
+// as a background. It's subtle and hard to see, but it's there.
+void EntityLightningCloud(Entity* self) {
+    if (self->step == 0) {
         InitializeEntity(D_80180B18);
-        entity->zPriority = 0x29;
-        entity->flags &= ~FLAG_POS_CAMERA_LOCKED;
-        entity->animCurFrame = entity->params + 0x22;
-        entity->posX.i.hi = D_8018139C[entity->params << 1];
-        entity->posY.i.hi = D_8018139E[entity->params << 1];
-        entity->ext.generic.unk80.modeS16.unk0 = 5;
+        self->zPriority = 0x29;
+        self->flags &= ~FLAG_POS_CAMERA_LOCKED;
+        // There are 3 shapes of cloud, this picks which one.
+        self->animCurFrame = self->params + 0x22;
+        self->posX.i.hi = D_8018139C[self->params << 1];
+        self->posY.i.hi = D_8018139E[self->params << 1];
+        self->ext.backgroundLightning.timer = 5;
     }
-    entity->ext.generic.unk80.modeS16.unk0--;
-    if ((entity->ext.generic.unk80.modeS16.unk0 << 0x10) == 0) {
-        DestroyEntity(entity);
+
+    if (--self->ext.backgroundLightning.timer == 0) {
+        DestroyEntity(self);
     }
 }
 

src/st/no3/no3.h

@@ -49,7 +49,7 @@ typedef enum EntityIDs {
     /* 0x1E */ E_CAVERN_DOOR_LEVER_UNK0 = 0x1E,
     /* 0x27 */ E_FALLING_ROCK_2 = 0x27,
     /* 0x29 */ E_LIGHTNING_THUNDER = 0x29,
-    /* 0x2A */ E_ID_2A,
+    /* 0x2A */ E_LIGHTNING_CLOUD,
     /* 0x2E */ E_ID_2E = 0x2E,
     /* 0x30 */ E_ID_30 = 0x30,
     /* 0x31 */ E_ID_31,

src/st/np3/32830.c

@@ -50,7 +50,7 @@ void EntityBackgroundLightning(Entity* self) {
             }
             newEntity = AllocEntity(&g_Entities[224], &g_Entities[256]);
             if (newEntity != NULL) {
-                CreateEntityFromCurrentEntity(E_801B5E98, newEntity);
+                CreateEntityFromCurrentEntity(E_LIGHTNING_CLOUD, newEntity);
                 if (random0to3 >= 3) {
                     random0to3 = 0;
                 }
@@ -1583,18 +1583,21 @@ void EntityLightningThunder(Entity* self) {
     }
 }
 
-void func_801B5E98(Entity* self) {
+// When lightning strikes, we get a bright bolt, but it is against a cloud
+// as a background. It's subtle and hard to see, but it's there.
+void EntityLightningCloud(Entity* self) {
     if (self->step == 0) {
         InitializeEntity(D_80180AA8);
         self->zPriority = 0x29;
         self->flags &= ~FLAG_POS_CAMERA_LOCKED;
+        // There are 3 shapes of cloud, this picks which one.
         self->animCurFrame = self->params + 0x22;
         self->posX.i.hi = D_80181220[self->params][0];
         self->posY.i.hi = D_80181220[self->params][1];
-        self->ext.generic.unk80.modeS16.unk0 = 5;
+        self->ext.backgroundLightning.timer = 5;
     }
 
-    if (--self->ext.generic.unk80.modeS16.unk0 == 0) {
+    if (--self->ext.backgroundLightning.timer == 0) {
         DestroyEntity(self);
     }
 }

src/st/np3/e_init.c

@@ -41,7 +41,7 @@ void EntityMermanRockRightSide(Entity* self);
 void func_801B5488(Entity* self);
 void EntityFallingRock2(Entity* self);
 void EntityLightningThunder(Entity* self);
-void func_801B5E98(Entity* self);
+void EntityLightningCloud(Entity* self);
 void EntitySwitch(Entity* self);
 void EntityHeartRoomGoldDoor(Entity* self);
 void EntityAlucardWaterEffect(Entity* self);
@@ -134,7 +134,7 @@ PfnEntityUpdate PfnEntityUpdates[] = {
     func_801B5488,
     EntityFallingRock2,
     EntityLightningThunder,
-    func_801B5E98,
+    EntityLightningCloud,
     EntitySwitch,
     EntityHeartRoomGoldDoor,
     EntityAlucardWaterEffect,

src/st/np3/np3.h

@@ -30,7 +30,7 @@ typedef enum {
     /* 0x1E */ E_CAVERN_DOOR_LEVER_UNK0 = 0x1E,
     /* 0x27 */ E_FALLING_ROCK_2 = 0x27,
     /* 0x28 */ E_LIGHTNING_THUNDER,
-    /* 0x29 */ E_801B5E98,
+    /* 0x29 */ E_LIGHTNING_CLOUD,
     /* 0x2D */ E_SPLASH_WATER = 0x2D,
     /* 0x2E */ E_SURFACING_WATER,
     /* 0x2F */ E_SIDE_WATER_SPLASH,