refactor: optimize snake sprite rendering using preloaded directional assets and implement HUD caching

source/game_input.cpp

@@ -26,6 +26,7 @@ bool handle_input_frame(InputContext &ctx) {
             setBackdropColor(RGB15(0, 0, 0));
             consoleSelect(ctx.topScreen);
             consoleClear();
+            invalidate_hud(*ctx.renderAssets);
         }
     }
 
@@ -115,11 +116,13 @@ bool handle_input_frame(InputContext &ctx) {
                 audio_play_pause(*ctx.audio);
                 audio_pause_music_if_enabled(*ctx.audio);
                 puts("\x1b[11;12HPaused");
+                invalidate_hud(*ctx.renderAssets);
             } else {
                 audio_resume_music_if_enabled(*ctx.audio);
                 audio_play_unpause(*ctx.audio);
                 consoleSelect(ctx.topScreen);
                 consoleClear();
+                invalidate_hud(*ctx.renderAssets);
             }
         } else {
             ctx.init_game();

source/game_render.cpp

@@ -8,190 +8,273 @@
 
 namespace {
 
-const void *get_sprite_pointer(uint16_t spriteIndex) {
-    return &tilemapTiles[spriteIndex * 16];
+void draw_snake_head(const GameState &state, const RenderAssets &assets,
+                     uint16_t &oamId) {
+  if (oamId >= 128 || state.snake.empty()) {
+    return;
+  }
+
+  const std::array<int, 3> dot = state.snake.front();
+  u16 *headGfx = nullptr;
+  bool hflip = false;
+  bool vflip = false;
+
+  switch (state.snakeDirection) {
+  case 0: // Up
+    headGfx = assets.gfx_head_v;
+    break;
+  case 1: // Right
+    headGfx = assets.gfx_head_h;
+    break;
+  case 2: // Down
+    headGfx = assets.gfx_head_v;
+    vflip = true;
+    break;
+  case 3: // Left
+    headGfx = assets.gfx_head_h;
+    hflip = true;
+    break;
+  default:
+    headGfx = assets.gfx_head_h;
+    break;
+  }
+
+  oamSet(&oamSub, oamId, dot[0] * 8, dot[1] * 8, 0, 0, SpriteSize_8x8,
+         SpriteColorFormat_256Color, headGfx, -1, false, false, hflip, vflip,
+         false);
+  oamId++;
 }
 
-void draw_snake_head(const GameState &state, const RenderAssets &assets, uint16_t &oamId) {
-    const std::array<int, 3> dot = state.snake.front();
-    bool hflip = false;
-    bool vflip = false;
+void draw_snake_tail(const GameState &state, const RenderAssets &assets,
+                     uint16_t &oamId) {
+  if (oamId >= 128 || state.snake.size() < 2) {
+    return;
+  }
 
-    switch (state.snakeDirection) {
-    case 0:
-        dmaCopy(&tilemapTiles[64], assets.gfx_head, 64);
-        break;
-    case 1:
-        dmaCopy(&tilemapTiles[48], assets.gfx_head, 64);
-        break;
-    case 2:
-        dmaCopy(&tilemapTiles[64], assets.gfx_head, 64);
-        vflip = true;
-        break;
-    case 3:
-        dmaCopy(&tilemapTiles[48], assets.gfx_head, 64);
-        hflip = true;
-        break;
-    default:
-        break;
+  const std::array<int, 3> dot = state.snake.back();
+  const size_t var = (state.snake.size() - 1) % 2;
+  u16 *tailGfx = nullptr;
+  bool hflip = false;
+  bool vflip = false;
+
+  switch (state.snake.at(state.snake.size() - 2).at(2)) {
+  case 0: // Up
+    tailGfx = assets.gfx_tail_v[var];
+    vflip = true;
+    break;
+  case 1: // Right
+    tailGfx = assets.gfx_tail_h[var];
+    hflip = true;
+    break;
+  case 2: // Down
+    tailGfx = assets.gfx_tail_v[var];
+    break;
+  case 3: // Left
+    tailGfx = assets.gfx_tail_h[var];
+    break;
+  default:
+    tailGfx = assets.gfx_tail_h[var];
+    break;
+  }
+
+  oamSet(&oamSub, oamId, dot[0] * 8, dot[1] * 8, 0, 0, SpriteSize_8x8,
+         SpriteColorFormat_256Color, tailGfx, -1, false, false, hflip, vflip,
+         false);
+  oamId++;
+}
+
+void draw_snake(const GameState &state, const RenderAssets &assets,
+                uint16_t &oamId) {
+  if (state.snake.empty()) {
+    return;
+  }
+
+  draw_snake_head(state, assets, oamId);
+
+  for (size_t i = 1; i + 1 < state.snake.size(); i++) {
+    if (oamId >= 128) {
+      return;
     }
-
-    oamSet(&oamSub, oamId, dot[0] * 8, dot[1] * 8, 0, 0, SpriteSize_8x8, SpriteColorFormat_256Color,
-           assets.gfx_head, -1, false, false, hflip, vflip, false);
+    oamSet(&oamSub, oamId, state.snake[i][0] * 8, state.snake[i][1] * 8, 0, 0,
+           SpriteSize_8x8, SpriteColorFormat_256Color,
+           (i % 2) ? assets.gfx_segment_small : assets.gfx_segment, -1, false,
+           false, false, false, false);
     oamId++;
-}
-
-void draw_snake_tail(const GameState &state, const RenderAssets &assets, uint16_t &oamId) {
-    const std::array<int, 3> dot = state.snake.back();
-    bool hflip = false;
-    bool vflip = false;
-
-    switch (state.snake.at(state.snake.size() - 2).at(2)) {
-    case 0:
-        dmaCopy(get_sprite_pointer(9 + ((state.snake.size() - 1) % 2)), assets.gfx_tail, 64);
-        vflip = true;
-        break;
-    case 1:
-        dmaCopy(get_sprite_pointer(7 + ((state.snake.size() - 1) % 2)), assets.gfx_tail, 64);
-        hflip = true;
-        break;
-    case 2:
-        dmaCopy(get_sprite_pointer(9 + ((state.snake.size() - 1) % 2)), assets.gfx_tail, 64);
-        break;
-    case 3:
-        dmaCopy(get_sprite_pointer(7 + ((state.snake.size() - 1) % 2)), assets.gfx_tail, 64);
-        break;
-    default:
-        break;
-    }
-
-    oamSet(&oamSub, oamId, dot[0] * 8, dot[1] * 8, 0, 0, SpriteSize_8x8, SpriteColorFormat_256Color,
-           assets.gfx_tail, -1, false, false, hflip, vflip, false);
-    oamId++;
-}
-
-void draw_snake(const GameState &state, const RenderAssets &assets, uint16_t &oamId) {
-    draw_snake_head(state, assets, oamId);
-
-    for (size_t i = 1; i < state.snake.size() - 1; i++) {
-        oamSet(&oamSub, oamId, state.snake[i][0] * 8, state.snake[i][1] * 8, 0, 0, SpriteSize_8x8,
-               SpriteColorFormat_256Color, (i % 2) ? assets.gfx_segment_small : assets.gfx_segment, -1,
-               false, false, false, false, false);
-        oamId++;
-    }
+  }
 
+  if (state.snake.size() > 1) {
     draw_snake_tail(state, assets, oamId);
+  }
 }
 
-void draw_apples(const GameState &state, const RenderAssets &assets, uint16_t &oamId) {
-    for (const std::array<int, 2> &apple : state.apples) {
-        oamSet(&oamSub, oamId, apple[0] * 8, apple[1] * 8, 0, 0, SpriteSize_8x8,
-               SpriteColorFormat_256Color, assets.gfx_apple, -1, false, false, false, false, false);
-        oamId++;
+void draw_apples(const GameState &state, const RenderAssets &assets,
+                 uint16_t &oamId) {
+  u16 *appleGfx =
+      (state.ticks % 4 == 0) ? assets.gfx_apple_blink : assets.gfx_apple;
+  for (const std::array<int, 2> &apple : state.apples) {
+    if (oamId >= 128) {
+      return;
     }
+    oamSet(&oamSub, oamId, apple[0] * 8, apple[1] * 8, 0, 0, SpriteSize_8x8,
+           SpriteColorFormat_256Color, appleGfx, -1, false, false, false, false,
+           false);
+    oamId++;
+  }
 }
 
-void draw_apples_rotten(const GameState &state, const RenderAssets &assets, uint16_t &oamId) {
-    for (const std::array<int, 2> &apple : state.bad_apples) {
-        oamSet(&oamSub, oamId, apple[0] * 8, apple[1] * 8, 0, 0, SpriteSize_8x8,
-               SpriteColorFormat_256Color, assets.gfx_apple_rotten, -1, false, false, false, false,
-               false);
-        oamId++;
+void draw_apples_rotten(const GameState &state, const RenderAssets &assets,
+                        uint16_t &oamId) {
+  for (const std::array<int, 2> &apple : state.bad_apples) {
+    if (oamId >= 128) {
+      return;
     }
+    oamSet(&oamSub, oamId, apple[0] * 8, apple[1] * 8, 0, 0, SpriteSize_8x8,
+           SpriteColorFormat_256Color, assets.gfx_apple_rotten, -1, false,
+           false, false, false, false);
+    oamId++;
+  }
 }
 
-void draw_apples_cursed(const GameState &state, const RenderAssets &assets, uint16_t &oamId) {
-    for (const std::array<int, 2> &apple : state.cursed_apples) {
-        oamSet(&oamSub, oamId, apple[0] * 8, apple[1] * 8, 0, 0, SpriteSize_8x8,
-               SpriteColorFormat_256Color, assets.gfx_apple_cursed, -1, false, false, false, false,
-               false);
-        oamId++;
+void draw_apples_cursed(const GameState &state, const RenderAssets &assets,
+                        uint16_t &oamId) {
+  for (const std::array<int, 2> &apple : state.cursed_apples) {
+    if (oamId >= 128) {
+      return;
     }
+    oamSet(&oamSub, oamId, apple[0] * 8, apple[1] * 8, 0, 0, SpriteSize_8x8,
+           SpriteColorFormat_256Color, assets.gfx_apple_cursed, -1, false,
+           false, false, false, false);
+    oamId++;
+  }
 }
 
 } // namespace
 
+void invalidate_hud(RenderAssets &assets) { assets.hudCache.dirty = true; }
+
 void draw_game(const GameState &state, const RenderAssets &assets) {
-    uint16_t oamId = 0;
+  uint16_t oamId = 0;
 
-    if (!state.gameOver) {
-        draw_apples(state, assets, oamId);
-        draw_apples_rotten(state, assets, oamId);
-        draw_apples_cursed(state, assets, oamId);
-        draw_snake(state, assets, oamId);
-        return;
+  if (!state.gameOver) {
+    draw_apples(state, assets, oamId);
+    draw_apples_rotten(state, assets, oamId);
+    draw_apples_cursed(state, assets, oamId);
+    draw_snake(state, assets, oamId);
+
+    // Hide all unused sprites up to hardware limit (128) to eliminate trailing
+    // ghost sprites
+    if (oamId < 128) {
+      oamClear(&oamSub, oamId, 128 - oamId);
     }
+    return;
+  }
 
-    iprintf("\x1b[11;12HGAME OVER!");
-    consoleSelect(assets.topScreen);
-    iprintf("\x1b[10;13HGAME OVER!");
+  // On Game Over, hide all sprites so none are left dangling
+  oamClear(&oamSub, 0, 128);
+
+  iprintf("\x1b[11;12HGAME OVER!");
+  consoleSelect(assets.topScreen);
+  iprintf("\x1b[10;13HGAME OVER!");
 }
 
-void draw_stats(const GameState &state, bool internals, bool musicEnabled, uint8_t frame) {
-    if (internals) {
-        iprintf("\x1b[0;0HFrame = %i\nTick = %i\ndir = %i", frame, state.ticks, state.snakeDirection);
-        iprintf("\x1b[3;0HLength: %i", state.snakelength);
-        iprintf("\x1b[4;0Hx=%i\ny=%i", state.snake.front()[0], state.snake.front()[1]);
+void draw_stats(const GameState &state, RenderAssets &assets, bool internals,
+                bool musicEnabled, uint8_t frame) {
+  if (internals) {
+    iprintf("\x1b[0;0HFrame = %i\nTick = %i\ndir = %i", frame, state.ticks,
+            state.snakeDirection);
+    iprintf("\x1b[3;0HLength: %i", state.snakelength);
+    if (!state.snake.empty()) {
+      iprintf("\x1b[4;0Hx=%i\ny=%i", state.snake.front()[0],
+              state.snake.front()[1]);
     }
+  }
 
+  HudCache &cache = assets.hudCache;
+  const bool cursed = (state.curseTicksRemaining > 0);
+
+  const bool needs_score_update = cache.dirty || (cache.score != state.score);
+  const bool needs_curse_update = cache.dirty || (cache.cursed != cursed);
+  const bool needs_pause_update =
+      cache.dirty || (cache.paused != state.paused) ||
+      (cache.musicEnabled != musicEnabled) ||
+      (cache.hardMode != state.hardMode) || (cache.gameOver != state.gameOver);
+
+  if (needs_score_update) {
     iprintf("\x1b[10;12HScore: %i", state.score);
+    cache.score = state.score;
+  }
 
-    if (state.curseTicksRemaining > 0) {
-        iprintf("\x1b[1;7HCONTROLS INVERTED!");
+  if (needs_curse_update) {
+    if (cursed) {
+      iprintf("\x1b[1;7HCONTROLS INVERTED!");
     } else {
-        iprintf("\x1b[1;7H                  ");
+      iprintf("\x1b[1;7H                  ");
     }
+    cache.cursed = cursed;
+  }
 
+  if (needs_pause_update) {
     if (!state.paused) {
-        if (state.gameOver) {
-            iprintf("\x1b[23;0HB = Main Menu");
-        }
-        return;
-    }
-
-    iprintf("\x1b[21;0HB = Main Menu");
-
-    if (musicEnabled) {
-        iprintf("\x1b[23;0HX = Disable Music");
+      if (state.gameOver) {
+        iprintf("\x1b[23;0HB = Main Menu");
+      } else if (cache.paused) {
+        // Clear any leftover pause strings if previously paused
+        iprintf("\x1b[21;0H             ");
+        iprintf("\x1b[22;0H                           ");
+        iprintf("\x1b[23;0H                  ");
+      }
     } else {
-        iprintf("\x1b[23;0HX = Enable Music ");
-    }
-
-    if (state.hardMode) {
+      iprintf("\x1b[21;0HB = Main Menu");
+      if (state.hardMode) {
         iprintf("\x1b[22;0HY = Restart in normal mode");
-    } else {
-        iprintf("\x1b[22;0HY = Restart in Hard mode");
+      } else {
+        iprintf("\x1b[22;0HY = Restart in Hard mode  ");
+      }
+      if (musicEnabled) {
+        iprintf("\x1b[23;0HX = Disable Music");
+      } else {
+        iprintf("\x1b[23;0HX = Enable Music ");
+      }
     }
+    cache.paused = state.paused;
+    cache.musicEnabled = musicEnabled;
+    cache.hardMode = state.hardMode;
+    cache.gameOver = state.gameOver;
+  }
+
+  cache.dirty = false;
 }
 
-void draw_menu(const GameState &state, const RenderAssets &assets, bool musicEnabled) {
-    oamClear(&oamSub, 0, 0);
-    oamUpdate(&oamSub);
+void draw_menu(const GameState &state, RenderAssets &assets,
+               bool musicEnabled) {
+  invalidate_hud(assets);
 
-    consoleSelect(assets.bottomScreen);
-    consoleClear();
+  oamClear(&oamSub, 0, 128);
+  oamUpdate(&oamSub);
 
-    consoleSelect(assets.topScreen);
-    consoleClear();
+  consoleSelect(assets.bottomScreen);
+  consoleClear();
 
-    iprintf("\x1b[3;10HSNAKE PLUS");
-    iprintf("\x1b[5;5H---------------------");
+  consoleSelect(assets.topScreen);
+  consoleClear();
 
-    const char *hardModeLabel = state.hardMode ? "ON " : "OFF";
-    const char *musicLabel = musicEnabled ? "ON " : "OFF";
+  iprintf("\x1b[3;10HSNAKE PLUS");
+  iprintf("\x1b[5;5H---------------------");
 
-    iprintf("\x1b[8;7H%c Start Game", state.menuSelection == 0 ? '>' : ' ');
-    iprintf("\x1b[10;7H%c Hard Mode: %s", state.menuSelection == 1 ? '>' : ' ', hardModeLabel);
-    iprintf("\x1b[12;7H%c Music: %s", state.menuSelection == 2 ? '>' : ' ', musicLabel);
+  const char *hardModeLabel = state.hardMode ? "ON " : "OFF";
+  const char *musicLabel = musicEnabled ? "ON " : "OFF";
 
-    iprintf("\x1b[19;3HUP/DOWN: Navigate");
-    iprintf("\x1b[20;3HA/START: Select");
+  iprintf("\x1b[8;7H%c Start Game", state.menuSelection == 0 ? '>' : ' ');
+  iprintf("\x1b[10;7H%c Hard Mode: %s", state.menuSelection == 1 ? '>' : ' ',
+          hardModeLabel);
+  iprintf("\x1b[12;7H%c Music: %s", state.menuSelection == 2 ? '>' : ' ',
+          musicLabel);
+
+  iprintf("\x1b[19;3HUP/DOWN: Navigate");
+  iprintf("\x1b[20;3HA/START: Select");
 }
 
-void blink_apples(const GameState &state, u16 *gfx_apple) {
-    if (state.ticks % 4) {
-        dmaCopy(get_sprite_pointer(5), gfx_apple, 64);
-    } else {
-        dmaCopy(get_sprite_pointer(6), gfx_apple, 64);
-    }
+void blink_apples(const GameState & /*state*/, u16 * /*gfx_apple*/) {
+  // Blinking is now handled directly by draw_apples() via sprite pointer
+  // selection without DMA.
 }

source/main.cpp

@@ -47,7 +47,7 @@ AudioContext audioContext;
 
 RenderAssets renderAssets;
 
-const void * get_sprite_pointer(uint16 spriteIndex) {
+const void * get_sprite_pointer(uint16_t spriteIndex) {
 	return &tilemapTiles[spriteIndex*16];
 }
 
@@ -69,16 +69,27 @@ void setup() {
 
 	renderAssets.gfx_segment = oamAllocateGfx(&oamSub, SpriteSize_8x8, SpriteColorFormat_256Color);
 	renderAssets.gfx_segment_small = oamAllocateGfx(&oamSub, SpriteSize_8x8, SpriteColorFormat_256Color);
-	renderAssets.gfx_head = oamAllocateGfx(&oamSub, SpriteSize_8x8, SpriteColorFormat_256Color);
+	renderAssets.gfx_head_h = oamAllocateGfx(&oamSub, SpriteSize_8x8, SpriteColorFormat_256Color);
+	renderAssets.gfx_head_v = oamAllocateGfx(&oamSub, SpriteSize_8x8, SpriteColorFormat_256Color);
 	renderAssets.gfx_apple = oamAllocateGfx(&oamSub, SpriteSize_8x8, SpriteColorFormat_256Color);
+	renderAssets.gfx_apple_blink = oamAllocateGfx(&oamSub, SpriteSize_8x8, SpriteColorFormat_256Color);
+	renderAssets.gfx_tail_h[0] = oamAllocateGfx(&oamSub, SpriteSize_8x8, SpriteColorFormat_256Color);
+	renderAssets.gfx_tail_h[1] = oamAllocateGfx(&oamSub, SpriteSize_8x8, SpriteColorFormat_256Color);
+	renderAssets.gfx_tail_v[0] = oamAllocateGfx(&oamSub, SpriteSize_8x8, SpriteColorFormat_256Color);
+	renderAssets.gfx_tail_v[1] = oamAllocateGfx(&oamSub, SpriteSize_8x8, SpriteColorFormat_256Color);
 	renderAssets.gfx_apple_rotten = oamAllocateGfx(&oamSub, SpriteSize_8x8, SpriteColorFormat_256Color);
 	renderAssets.gfx_apple_cursed = oamAllocateGfx(&oamSub, SpriteSize_8x8, SpriteColorFormat_256Color);
-	renderAssets.gfx_tail = oamAllocateGfx(&oamSub, SpriteSize_8x8, SpriteColorFormat_256Color);
 
 	dmaCopy(get_sprite_pointer(1), renderAssets.gfx_segment, 64);
 	dmaCopy(get_sprite_pointer(2), renderAssets.gfx_segment_small, 64);
-	dmaCopy(get_sprite_pointer(3), renderAssets.gfx_head, 64);
+	dmaCopy(get_sprite_pointer(3), renderAssets.gfx_head_h, 64);
+	dmaCopy(get_sprite_pointer(4), renderAssets.gfx_head_v, 64);
 	dmaCopy(get_sprite_pointer(5), renderAssets.gfx_apple, 64);
+	dmaCopy(get_sprite_pointer(6), renderAssets.gfx_apple_blink, 64);
+	dmaCopy(get_sprite_pointer(7), renderAssets.gfx_tail_h[0], 64);
+	dmaCopy(get_sprite_pointer(8), renderAssets.gfx_tail_h[1], 64);
+	dmaCopy(get_sprite_pointer(9), renderAssets.gfx_tail_v[0], 64);
+	dmaCopy(get_sprite_pointer(10), renderAssets.gfx_tail_v[1], 64);
 	dmaCopy(get_sprite_pointer(11), renderAssets.gfx_apple_rotten, 64);
 
 	consoleSelect(&topScreen);
@@ -118,7 +129,7 @@ void handle_vblank() {
 	frame++;
 	if (gameState.scene == Scene::Playing) {
 		consoleSelect(&topScreen);
-		draw_stats(gameState, internals, audio_is_music_enabled(audioContext), frame);
+		draw_stats(gameState, renderAssets, internals, audio_is_music_enabled(audioContext), frame);
 	}
 	oamUpdate(&oamSub);
 	//flashy_colors();
@@ -155,7 +166,6 @@ void do_tick() {
 				audio_stop_music();
 				audio_play_fail(audioContext);
 			}
-			blink_apples(gameState, renderAssets.gfx_apple);
 			//consoleSelect(&bottomScreen);
 			draw_game(gameState, renderAssets);
 		} 
@@ -179,9 +189,10 @@ void init_game() {
 		gameState.cursed_apples.clear();
 		consoleSelect(&topScreen);
 		consoleClear();
+		invalidate_hud(renderAssets);
 		consoleSelect(&bottomScreen);
 		consoleClear();
-		oamClear(&oamSub,0,0);
+		oamClear(&oamSub,0,128);
 		audio_start_music(audioContext);
 	} 
 	else
@@ -198,9 +209,10 @@ void init_game() {
 		gameState.cursed_apples.clear();
 		consoleSelect(&topScreen);
 		consoleClear();
+		invalidate_hud(renderAssets);
 		consoleSelect(&bottomScreen);
 		consoleClear();
-		oamClear(&oamSub,0,0);
+		oamClear(&oamSub,0,128);
 		audio_start_music(audioContext);
 	}