Add a main menu scene with Start/Hard Mode/Music options

The game now boots into a menu (Start Game, Hard Mode toggle, Music
toggle) navigated with Up/Down and A/Start, instead of dropping
straight into a match. B returns to the menu from a paused or
game-over state.

include/game_render.h

@@ -20,6 +20,7 @@ struct RenderAssets {
 
 void draw_game(const GameState &state, const RenderAssets &assets);
 void draw_stats(const GameState &state, bool internals, bool musicEnabled, uint8_t frame);
+void draw_menu(const GameState &state, const RenderAssets &assets, bool musicEnabled);
 void blink_apples(const GameState &state, u16 *gfx_apple);
 
 #endif

include/game_state.h

@@ -6,6 +6,13 @@
 #include <vector>
 #include <nds/ndstypes.h>
 
+enum class Scene {
+    Menu,
+    Playing,
+};
+
+constexpr int MENU_ITEM_COUNT = 3;
+
 struct GameState {
     volatile uint16_t ticks = 0;
     volatile uint16_t snakelength = 0;
@@ -16,6 +23,9 @@ struct GameState {
     bool paused = false;
     bool hardMode = false;
 
+    Scene scene = Scene::Menu;
+    int menuSelection = 0;
+
     uint16_t curseTicksRemaining = 0;
 
     std::deque<std::array<int, 3>> snake;

source/game_input.cpp

@@ -29,6 +29,43 @@ bool handle_input_frame(InputContext &ctx) {
         }
     }
 
+    if (ctx.state->scene == Scene::Menu) {
+        if ((keys != 0U) && ((keys & (KEY_UP | KEY_DOWN)) != 0U)) {
+            const int delta = ((keys & KEY_UP) != 0U) ? -1 : 1;
+            ctx.state->menuSelection = (ctx.state->menuSelection + delta + MENU_ITEM_COUNT) % MENU_ITEM_COUNT;
+            draw_menu(*ctx.state, *ctx.renderAssets, audio_is_music_enabled(*ctx.audio));
+        }
+
+        if ((keys != 0U) && (((keys & KEY_A) != 0U) || ((keys & KEY_START) != 0U))) {
+            switch (ctx.state->menuSelection) {
+            case 0:
+                ctx.state->scene = Scene::Playing;
+                ctx.init_game();
+                draw_game(*ctx.state, *ctx.renderAssets);
+                break;
+            case 1:
+                ctx.state->hardMode = !ctx.state->hardMode;
+                draw_menu(*ctx.state, *ctx.renderAssets, audio_is_music_enabled(*ctx.audio));
+                break;
+            case 2:
+                audio_toggle_music(*ctx.audio);
+                draw_menu(*ctx.state, *ctx.renderAssets, audio_is_music_enabled(*ctx.audio));
+                break;
+            default:
+                break;
+            }
+        }
+
+        return true;
+    }
+
+    if ((ctx.state->paused || ctx.state->gameOver) && (keys != 0U) && ((keys & KEY_B) != 0U)) {
+        ctx.state->scene = Scene::Menu;
+        ctx.state->paused = false;
+        draw_menu(*ctx.state, *ctx.renderAssets, audio_is_music_enabled(*ctx.audio));
+        return true;
+    }
+
     if (!ctx.state->paused && !ctx.state->gameOver) {
         const bool cursed = ctx.state->curseTicksRemaining > 0;
 

source/game_render.cpp

@@ -143,9 +143,14 @@ void draw_stats(const GameState &state, bool internals, bool musicEnabled, uint8
     }
 
     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");
     } else {
@@ -159,6 +164,30 @@ void draw_stats(const GameState &state, bool internals, bool musicEnabled, uint8
     }
 }
 
+void draw_menu(const GameState &state, const RenderAssets &assets, bool musicEnabled) {
+    oamClear(&oamSub, 0, 0);
+    oamUpdate(&oamSub);
+
+    consoleSelect(assets.bottomScreen);
+    consoleClear();
+
+    consoleSelect(assets.topScreen);
+    consoleClear();
+
+    iprintf("\x1b[3;10HSNAKE PLUS");
+    iprintf("\x1b[5;5H---------------------");
+
+    const char *hardModeLabel = state.hardMode ? "ON " : "OFF";
+    const char *musicLabel = musicEnabled ? "ON " : "OFF";
+
+    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);

source/main.cpp

@@ -57,6 +57,7 @@ void setup() {
 	videoSetMode(MODE_0_2D);
 	videoSetModeSub(MODE_0_2D);
 	
+	vramSetBankA(VRAM_A_MAIN_BG);
 	vramSetBankC(VRAM_C_SUB_BG);
 	vramSetBankD(VRAM_D_SUB_SPRITE);
 	consoleInit(&topScreen, 3,BgType_Text4bpp, BgSize_T_256x256, X_MAX, 0, true, true);
@@ -115,14 +116,16 @@ void setup() {
 }
 void handle_vblank() {
 	frame++;
+	if (gameState.scene == Scene::Playing) {
 		consoleSelect(&topScreen);
 		draw_stats(gameState, internals, audio_is_music_enabled(audioContext), frame);
+	}
 	oamUpdate(&oamSub);
 	//flashy_colors();
 }
 
 void do_tick() {
-	if (!paused) {
+	if (gameState.scene == Scene::Playing && !paused) {
 		ticks++;
 		if (!gameOver){
 			const bool wasGameOver = gameOver;
@@ -211,9 +214,7 @@ int main(void) {
 	irqSet(IRQ_VBLANK, handle_vblank);
 
 	setup();
-	init_game();
-
-	// Start timer for game ticks
+	draw_menu(gameState, renderAssets, audio_is_music_enabled(audioContext));
 
 	InputContext inputContext;
 	inputContext.state = &gameState;