Minor documentation

Some things I figured out while working on my hack.
- The Subsprite tables do not use `DISPLAY_WIDTH`, but rather use -16, since they are signed bytes. The negative numbers better illustrate what the tables are doing.
- Figured out the as-of-yet undocumented data in SpriteCB_FlygonSilhouette

src/battle_interface.c

@@ -318,10 +318,17 @@ static const struct SpriteTemplate sHealthbarSpriteTemplates[MAX_BATTLERS_COUNT]
     }
 };
 
+/*   v-- Origin
+[0   +         ][1     ]
+[              ][      ]   sUnused_Subsprites_0
+[              ][      ]   
+[______________][______]   96x40
+[2     ][3     ][4     ]
+*/
 static const struct Subsprite sUnused_Subsprites_0[] =
 {
     {
-        .x = DISPLAY_WIDTH,
+        .x = -16,
         .y = 0,
         .shape = SPRITE_SHAPE(64x32),
         .size = SPRITE_SIZE(64x32),
@@ -337,7 +344,7 @@ static const struct Subsprite sUnused_Subsprites_0[] =
         .priority = 1
     },
     {
-        .x = DISPLAY_WIDTH,
+        .x = -16,
         .y = 32,
         .shape = SPRITE_SHAPE(32x8),
         .size = SPRITE_SIZE(32x8),
@@ -362,10 +369,11 @@ static const struct Subsprite sUnused_Subsprites_0[] =
     }
 };
 
+// This subsprite table has the same layout as above, but offset by 64 base tiles.
 static const struct Subsprite sUnused_Subsprites_2[] =
 {
     {
-        .x = DISPLAY_WIDTH,
+        .x = -16,
         .y = 0,
         .shape = SPRITE_SHAPE(64x32),
         .size = SPRITE_SIZE(64x32),
@@ -381,7 +389,7 @@ static const struct Subsprite sUnused_Subsprites_2[] =
         .priority = 1
     },
     {
-        .x = DISPLAY_WIDTH,
+        .x = -16,
         .y = 32,
         .shape = SPRITE_SHAPE(32x8),
         .size = SPRITE_SIZE(32x8),
@@ -406,10 +414,16 @@ static const struct Subsprite sUnused_Subsprites_2[] =
     }
 };
 
+/*   v-- Origin
+[0   +         ][1     ]
+[              ][      ]
+[              ][      ]
+[              ][      ]   96x32
+*/
 static const struct Subsprite sUnused_Subsprites_1[] =
 {
     {
-        .x = DISPLAY_WIDTH,
+        .x = -16,
         .y = 0,
         .shape = SPRITE_SHAPE(64x32),
         .size = SPRITE_SIZE(64x32),
@@ -426,10 +440,11 @@ static const struct Subsprite sUnused_Subsprites_1[] =
     }
 };
 
+// Same as above
 static const struct Subsprite sUnused_Subsprites_3[] =
 {
     {
-        .x = DISPLAY_WIDTH,
+        .x = -16,
         .y = 0,
         .shape = SPRITE_SHAPE(64x32),
         .size = SPRITE_SIZE(64x32),
@@ -446,10 +461,13 @@ static const struct Subsprite sUnused_Subsprites_3[] =
     }
 };
 
+/*  v-- Origin
+[0  +  ][1     ]   64x8
+*/
 static const struct Subsprite sHealthBar_Subsprites_Player[] =
 {
     {
-        .x = DISPLAY_WIDTH,
+        .x = -16,
         .y = 0,
         .shape = SPRITE_SHAPE(32x8),
         .size = SPRITE_SIZE(32x8),
@@ -466,10 +484,14 @@ static const struct Subsprite sHealthBar_Subsprites_Player[] =
     }
 };
 
+/*       v-- Origin
+[]  [0  +  ][1     ]   72x8
+2^ ^--- Note 8px space
+*/
 static const struct Subsprite sHealthBar_Subsprites_Opponent[] =
 {
     {
-        .x = DISPLAY_WIDTH,
+        .x = -16,
         .y = 0,
         .shape = SPRITE_SHAPE(32x8),
         .size = SPRITE_SIZE(32x8),
@@ -485,7 +507,7 @@ static const struct Subsprite sHealthBar_Subsprites_Opponent[] =
         .priority = 1
     },
     {
-        .x = DISPLAY_WIDTH - 16,
+        .x = -32,
         .y = 0,
         .shape = SPRITE_SHAPE(8x8),
         .size = SPRITE_SIZE(8x8),

src/intro.c

@@ -3322,24 +3322,29 @@ static u8 CreateGameFreakLogoSprites(s16 x, s16 y, s16 unused)
 #undef sLetterX
 #undef COLOR_CHANGES
 
+#define sScale   data[1]
+#define sRot     data[2]
+#define sPos     data[3]
+#define sTimer   data[7]
+
 static void SpriteCB_FlygonSilhouette(struct Sprite *sprite)
 {
-    sprite->data[7]++;
+    sprite->sTimer++;
 
     if (sprite->sState != 0)
     {
-        s16 sin1;
+        s16 sin;
-        s16 sin2;
+        s16 cos;
 
         s16 a, b, c, d;
-
+        // Determines rotation of the sprite
-        sin1 = gSineTable[(u8)sprite->data[2]];
+        sin = gSineTable[(u8)sprite->sRot];
-        sin2 = gSineTable[(u8)(sprite->data[2] + 64)];
+        cos = gSineTable[(u8)(sprite->sRot + 64)];
-
+        // Converts rotation and scale into the OAM matrix
-        d = Q_8_8_TO_INT(sin2 * sprite->data[1]);
+        d = Q_8_8_TO_INT( cos * sprite->sScale);
-        c = Q_8_8_TO_INT(-sin1 * sprite->data[1]);
+        c = Q_8_8_TO_INT(-sin * sprite->sScale);
-        b = Q_8_8_TO_INT(sin1 * sprite->data[1]);
+        b = Q_8_8_TO_INT( sin * sprite->sScale);
-        a = Q_8_8_TO_INT(sin2 * sprite->data[1]);
+        a = Q_8_8_TO_INT( cos * sprite->sScale);
 
         SetOamMatrix(1, a, b, c, d);
     }
@@ -3353,36 +3358,41 @@ static void SpriteCB_FlygonSilhouette(struct Sprite *sprite)
         CalcCenterToCornerVec(sprite, SPRITE_SHAPE(64x32), SPRITE_SIZE(64x32), ST_OAM_AFFINE_DOUBLE);
         sprite->invisible = FALSE;
         sprite->sState = 1;
-        sprite->data[1] = 0x80;
+        sprite->sScale = 128;
-        sprite->data[2] = 0;
+        sprite->sRot = 0;
-        sprite->data[3] = 0;
+        sprite->sPos = 0;
         break;
     case 1:
-        sprite->x2 = -Sin((u8)sprite->data[3], 140);
+        sprite->x2 = -Sin((u8)sprite->sPos, 140);
-        sprite->y2 = -Sin((u8)sprite->data[3], 120);
+        sprite->y2 = -Sin((u8)sprite->sPos, 120);
-        sprite->data[1] += 7;
+        sprite->sScale += 7;
-        sprite->data[3] += 3;
+        sprite->sPos += 3;
         if (sprite->x + sprite->x2 <= -16)
         {
             sprite->oam.priority = 3;
             sprite->sState++;
             sprite->x = 20;
             sprite->y = 40;
-            sprite->data[1] = 0x200;
+            sprite->sScale = 512;
-            sprite->data[2] = 0;
+            sprite->sRot = 0;
-            sprite->data[3] = 0x10;
+            sprite->sPos = 16;
         }
         break;
     case 2:
-        sprite->x2 = Sin((u8)sprite->data[3], 34);
+        sprite->x2 = Sin((u8)sprite->sPos, 34);
-        sprite->y2 = -Cos((u8)sprite->data[3], 60);
+        sprite->y2 = -Cos((u8)sprite->sPos, 60);
-        sprite->data[1] += 2;
+        sprite->sScale += 2;
-        if (sprite->data[7] % 5 == 0)
+        if (sprite->sTimer % 5 == 0)
-            sprite->data[3]++;
+            sprite->sPos++;
         break;
     }
 }
 
+#undef sScale
+#undef sRot
+#undef sPos
+#undef sTimer
+
 static void SpriteCB_RayquazaOrb(struct Sprite *sprite)
 {
     u16 foo;