From 49d11225615f864b4a6b204219fe40b9d2b9e435 Mon Sep 17 00:00:00 2001
From: Bad Diode <bd@badd10de.dev>
Date: Wed, 21 Apr 2021 12:57:40 +0200
Subject: Add alternative sprite loading scheme

---
 src/main.c | 130 +++++++++++++++++++++++--------------------------------------
 1 file changed, 48 insertions(+), 82 deletions(-)

diff --git a/src/main.c b/src/main.c
index d7e54d8..59bf9d4 100644
--- a/src/main.c
+++ b/src/main.c
@@ -43,6 +43,7 @@
 #define DISP_BG_2       (1 << 10)
 #define DISP_BG_3       (1 << 11)
 #define DISP_OBJ        (1 << 12)
+#define DISP_ENABLE_SPRITES DISP_OBJ | DISP_OBJ_1D
 
 // Registers to control of BG layers.
 #define BG_CTRL_0 *((vu16*)(0x04000008 + 0x0000))
@@ -443,59 +444,54 @@ copy_font_to_tile_memory(Tile *tile) {
     }
 }
 
-static int bouncing_animation[] = {
-    0, 0, 0,
-    0, 0, 0,
-    0, 0, 0,
-    1, 1, 1,
-    2, 2, 2,
-    3, 3, 3,
-    5, 5, 5,
-    6, 6, 6,
-    7, 7, 7,
-    8, 8, 8,
-    7, 7, 7,
-    6, 6, 6,
-    5, 5, 5,
-    3, 3, 3,
-    2, 2, 2,
-    1, 1, 1,
-    0, 0, 0,
-    0, 0, 0,
-    0, 0, 0,
-};
-
-typedef struct FontSprite {
-    int x;
-    int y;
-    int animation_state;
-    u32 tile_index;
-    u32 pal_bank;
-} FontSprite;
+typedef struct Sprite {
+    // A unique sprite identifier.
+    size_t id;
+    // The number of tiles for a single sprite frame.
+    size_t n_tiles;
+    // The starting tile of this sprite.
+    size_t tile_start;
+    // The associated palette bank for this sprite.
+    size_t pal_bank;
+} Sprite;
 
 typedef struct ButtonSprite {
+    int id;
     int x;
     int y;
     int frame;
     int n_frames;
-    u32 tile_index;
-    u32 pal_bank;
 } ButtonSprite;
 
-void
-load_sprite_data(Tile *tile_ptr, u32 *sprite_data, size_t n_tiles) {
-    for (size_t i = 0; i < n_tiles; ++i) {
-        for (size_t j = 0; j < 8; ++j) {
-            tile_ptr->data[j] = *sprite_data++;
-        }
-        tile_ptr++;
-    }
+#define NUM_SPRITES 128
+
+Sprite sprites[NUM_SPRITES];
+
+// Keeping track of unique sprites and current sprite memory pointer using
+// global singletons.
+size_t sprite_counter = 0;
+size_t sprite_tile_counter = 0;
+u32 *sprite_memory = NULL;
+
+// Loads the sprite data into video memory and initialize the Sprite structure.
+size_t
+load_sprite_data(u32 *sprite_data, size_t n_tiles, size_t n_frames) {
+    memcpy(sprite_memory, sprite_data, 8 * n_tiles * n_frames * sizeof(u32));
+    sprite_memory += 8 * n_tiles * n_frames;
+    Sprite sprite = {
+        .id = sprite_counter,
+        .n_tiles = n_tiles,
+        .tile_start = sprite_tile_counter,
+    };
+    sprite_tile_counter += n_tiles * n_frames;
+    sprites[sprite_counter] = sprite;
+    return sprite_counter++;
 }
 
 int main(void) {
     // Configure the display in mode 0 to show OBJs, where tile memory is
     // sequential.
-    DISP_CTRL = DISP_MODE_3 | DISP_OBJ | DISP_OBJ_1D | DISP_BG_2;
+    DISP_CTRL = DISP_MODE_3 | DISP_ENABLE_SPRITES | DISP_BG_2;
 
     // Add colors to the sprite color palette. Tiles with color number 0 are
     // treated as transparent.
@@ -509,65 +505,35 @@ int main(void) {
         OBJ_ATTR_0(i) = (1 << 9);
     }
 
-    size_t initial_tile = 512;
-    Tile *tile_mem = &TILE_MEM[4][initial_tile];
-
-    // Test copying the exported tiles.
-    profile_start();
-    load_sprite_data(tile_mem, &gba_btn_b_data, 112);
-    tile_mem += 112;
-    load_sprite_data(tile_mem, &gba_btn_a_data, 112);
-    tile_mem += 112;
-    u32 perf_a_clk = profile_stop();
-    //
-    profile_start();
-    memcpy(tile_mem, &gba_btn_b_data, sizeof(gba_btn_b_data));
-    tile_mem += 112;
-    memcpy(tile_mem, &gba_btn_a_data, sizeof(gba_btn_a_data));
-    tile_mem += 112;
-    u32 perf_b_clk = profile_stop();
-
-    char perf_a[240] = {0};
-    char perf_b[240] = {0};
-    sprintf(perf_a, "A: %d", perf_a_clk);
-    sprintf(perf_b, "B: %d", perf_b_clk);
-
-    put_text(0, 0, COLOR_WHITE, perf_a);
-    put_text(0, 16, COLOR_WHITE, perf_b);
-
-    char msg[240] = {0};
-    sprintf(msg, "size[a]: %d", sizeof(gba_btn_a_data) / 8 / sizeof(u32));
-    put_text(0, 32, COLOR_RED, msg);
-    sprintf(msg, "size[b]: %d", sizeof(gba_btn_b_data) / 8 / sizeof(u32));
-    put_text(0, 32 + 16, COLOR_RED, msg);
+    sprite_tile_counter = 512;
+    sprite_memory = &TILE_MEM[4][sprite_tile_counter];
 
     // Initialize the A/B button sprites.
     int buttons_x = SCREEN_WIDTH - 64 - 10;
     int buttons_y = 120;
     ButtonSprite btn_b = {
+        .id = load_sprite_data(&gba_btn_b_data, 16, 7),
         .x = buttons_x,
         .y = buttons_y,
         .frame = 0,
         .n_frames = 6,
-        .tile_index = initial_tile,
-        .pal_bank = 0,
     };
-    OBJ_ATTR_0(0) = btn_b.y;
-    OBJ_ATTR_1(0) = btn_b.x | (1 << 0xF);
-    OBJ_ATTR_2(0) = btn_b.tile_index;
+    OBJ_ATTR_0(btn_b.id) = btn_b.y;
+    OBJ_ATTR_1(btn_b.id) = btn_b.x | (1 << 0xF);
+    OBJ_ATTR_2(btn_b.id) = sprites[btn_b.id].tile_start;
+
     ButtonSprite btn_a = {
+        .id = load_sprite_data(&gba_btn_a_data, 16, 7),
         .x = buttons_x + 20,
         .y = buttons_y - 16,
         .frame = 0,
         .n_frames = 6,
-        .tile_index = initial_tile + 112,
-        .pal_bank = 0,
     };
-    OBJ_ATTR_0(1) = btn_a.y;
-    OBJ_ATTR_1(1) = btn_a.x | (1 << 0xF);
-    OBJ_ATTR_2(1) = btn_a.tile_index;
+    OBJ_ATTR_0(btn_a.id) = btn_a.y;
+    OBJ_ATTR_1(btn_a.id) = btn_a.x | (1 << 0xF);
+    OBJ_ATTR_2(btn_a.id) = sprites[btn_a.id].tile_start;
 
-    // draw_logo();
+    draw_logo();
 
     int frame_counter = 0;
     while(true) {
-- 
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