Add snake tutorial draft

demos/snake-tutorial/.gitignore

@@ -0,0 +1 @@
+!*.c

demos/snake-tutorial/Makefile

@@ -0,0 +1,27 @@
+DATA_FILES=info.json sprites.png
+CFLAGS=$(shell rivemu -quiet -no-window -sdk -workspace -exec riv-opt-flags -Ospeed)
+
+all: snake-0.sqfs snake-1.sqfs snake-2.sqfs snake-3.sqfs snake-4.sqfs snake-5.sqfs snake-6.sqfs snake-7.sqfs snake-8.sqfs snake-8.sqfs
+
+snake-%.elf: snake-%.c
+	rivemu -quiet -no-window -sdk -workspace -exec "gcc $< -o $@ $(CFLAGS) && riv-strip $@"
+
+snake-%.sqfs: snake-%.elf $(DATA_FILES)
+	rivemu -quiet -no-window -sdk -workspace -exec "riv-mksqfs $(DATA_FILES) $< $@"
+
+test:
+	rivemu -quiet -workspace -exec riv-jit-c ./snake-0.c
+	rivemu -quiet -workspace -exec riv-jit-c ./snake-1.c
+	rivemu -quiet -workspace -exec riv-jit-c ./snake-2.c
+	rivemu -quiet -workspace -exec riv-jit-c ./snake-3.c
+	rivemu -quiet -workspace -exec riv-jit-c ./snake-4.c
+	rivemu -quiet -workspace -exec riv-jit-c ./snake-5.c
+	rivemu -quiet -workspace -exec riv-jit-c ./snake-6.c
+	rivemu -quiet -workspace -exec riv-jit-c ./snake-7.c
+
+lint:
+	gcc -fsyntax-only -fanalyzer -I../../libriv *.c
+	clang-tidy *.c -- -I../../libriv
+
+clean:
+	rm -f *.sqfs *.elf

demos/snake-tutorial/info.json

@@ -0,0 +1,6 @@
+{
+    "name": "Snake",
+    "summary": "Snake game from tutorial",
+    "description": "Use arrow to move, the game ends when the snake hits itself or a wall!",
+    "tags": ["puzzle", "2d", "snake"]
+}

demos/snake-tutorial/snake-0.c

@@ -0,0 +1,28 @@
+// Header including all RIV APIs
+#include <riv.h>
+
+// Called every frame to draw the game
+void draw() {
+    // Clear screen
+    riv_clear(RIV_COLOR_DARKSLATE);
+    // Draw snake title
+    riv_draw_text(
+        "snake",                  // text to draw
+        RIV_SPRITESHEET_FONT_5X7, // sprite sheet id of the font
+        RIV_CENTER,               // anchor point on the text bounding box
+        128,                      // anchor x
+        128,                      // anchor y
+        4,                        // text size multiplier
+        RIV_COLOR_LIGHTGREEN      // text color
+    );
+}
+
+// Entry point
+int main() {
+    // Main loop, keep presenting frames until user quit or game ends
+    do {
+        // Draw game graphics
+        draw();
+    } while(riv_present());
+    return 0;
+}

demos/snake-tutorial/snake-1.c

@@ -0,0 +1,34 @@
+// Customizing the resolution and frame rate
+
+// Header including all RIV APIs
+#include <riv.h>
+
+// Called every frame to draw the game
+void draw() {
+    // Clear screen
+    riv_clear(RIV_COLOR_DARKSLATE);
+    // Draw snake title
+    riv_draw_text(
+        "snake",                  // text to draw
+        RIV_SPRITESHEET_FONT_5X7, // sprite sheet id of the font
+        RIV_CENTER,               // anchor point on the text bounding box
+        64,                       // anchor x
+        64,                       // anchor y
+        2,                        // text size multiplier
+        RIV_COLOR_LIGHTGREEN      // text color
+    );
+}
+
+// Entry point
+int main() {
+    // Set screen size and default frame rate
+    riv->width = 128;
+    riv->height = 128;
+    riv->target_fps = 8;
+    // Main loop, keep presenting frames until user quit or game ends
+    do {
+        // Draw game graphics
+        draw();
+    } while(riv_present());
+    return 0;
+}

demos/snake-tutorial/snake-2.c

@@ -0,0 +1,101 @@
+// Starting the game
+
+// Header including all RIV APIs
+#include <riv.h>
+
+// Game state
+bool started; // true when game has started
+bool ended; // true when game has ended
+
+// Called when game starts
+void start_game() {
+    riv_printf("GAME START\n");
+    started = true;
+}
+
+// Called when game ends
+void end_game() {
+    riv_printf("GAME OVER\n");
+    ended = true;
+    // Quit in 3 seconds
+    riv->quit_frame = riv->frame + 3*riv->target_fps;
+}
+
+// Update game logic
+void update_game() {
+    // TODO: update game
+    end_game();
+}
+
+// Draw the game map
+void draw_game() {
+    // TODO: draw game
+}
+
+// Draw game start screen
+void draw_start_screen() {
+    // Draw snake title
+    riv_draw_text(
+        "snake",                  // text to draw
+        RIV_SPRITESHEET_FONT_5X7, // sprite sheet id of the font
+        RIV_CENTER,               // anchor point on the text bounding box
+        64,                       // anchor x
+        64,                       // anchor y
+        2,                        // text size multiplier
+        RIV_COLOR_LIGHTGREEN      // text color
+    );
+    // Make "press to start blink" by changing the color depending on the frame number
+    uint32_t col = (riv->frame % 2 == 0) ? RIV_COLOR_LIGHTRED : RIV_COLOR_DARKRED;
+    // Draw press to start
+    riv_draw_text("PRESS TO START", RIV_SPRITESHEET_FONT_5X7, RIV_CENTER, 64, 64+16, 1, col);
+}
+
+// Draw game over screen
+void draw_end_screen() {
+    // Draw last game frame
+    draw_game();
+    // Draw GAME OVER
+    riv_draw_text("GAME OVER", RIV_SPRITESHEET_FONT_5X7, RIV_CENTER, 64, 64, 2, RIV_COLOR_RED);
+}
+
+// Called every frame to update game state
+void update() {
+    if (!started) { // Game not started yet
+        // Let game start whenever a key has been pressed
+        if (riv->key_toggle_count > 0) {
+            start_game();
+        }
+    } else if (!ended) { // Game is progressing
+        update_game();
+    }
+}
+
+// Called every frame to draw the game
+void draw() {
+    // Clear screen
+    riv_clear(RIV_COLOR_DARKSLATE);
+    // Draw different screens depending on the game state
+    if (!started) { // Game not started yet
+        draw_start_screen();
+    } else if (!ended) { // Game is progressing
+        draw_game();
+    } else { // Game ended
+        draw_end_screen();
+    }
+}
+
+// Entry point
+int main() {
+    // Set screen size and default frame rate
+    riv->width = 128;
+    riv->height = 128;
+    riv->target_fps = 8;
+    // Main loop, keep presenting frames until user quit or game ends
+    do {
+        // Update game state
+        update();
+        // Draw game graphics
+        draw();
+    } while(riv_present());
+    return 0;
+}

demos/snake-tutorial/snake-3.c

@@ -0,0 +1,116 @@
+// Spawning the apple
+
+// Header including all RIV APIs
+#include <riv.h>
+
+// Constants
+enum {
+    MAP_SIZE = 16, // 16x16 tiles
+    TILE_SIZE = 8, // 8x8 pixels
+};
+
+// Game state
+bool started; // true when game has started
+bool ended; // true when game has ended
+riv_vec2i apple_pos; // position of the current apple
+
+// Spawn apple in a new position
+bool respawn_apple() {
+    apple_pos = (riv_vec2i){riv_rand_uint(MAP_SIZE-1), riv_rand_uint(MAP_SIZE-1)};
+    return true;
+}
+
+// Called when game starts
+void start_game() {
+    riv_printf("GAME START\n");
+    started = true;
+    respawn_apple();
+}
+
+// Called when game ends
+void end_game() {
+    riv_printf("GAME OVER\n");
+    ended = true;
+    // Quit in 3 seconds
+    riv->quit_frame = riv->frame + 3*riv->target_fps;
+}
+
+// Update game logic
+void update_game() {
+    // TODO: update game
+    end_game();
+}
+
+// Draw the game map
+void draw_game() {
+    // Draw apple
+    riv_draw_rect_fill(apple_pos.x*TILE_SIZE, apple_pos.y*TILE_SIZE, TILE_SIZE, TILE_SIZE, RIV_COLOR_LIGHTRED);
+}
+
+// Draw game start screen
+void draw_start_screen() {
+    // Draw snake title
+    riv_draw_text(
+        "snake",                  // text to draw
+        RIV_SPRITESHEET_FONT_5X7, // sprite sheet id of the font
+        RIV_CENTER,               // anchor point on the text bounding box
+        64,                       // anchor x
+        64,                       // anchor y
+        2,                        // text size multiplier
+        RIV_COLOR_LIGHTGREEN      // text color
+    );
+    // Make "press to start blink" by changing the color depending on the frame number
+    uint32_t col = (riv->frame % 2 == 0) ? RIV_COLOR_LIGHTRED : RIV_COLOR_DARKRED;
+    // Draw press to start
+    riv_draw_text("PRESS TO START", RIV_SPRITESHEET_FONT_5X7, RIV_CENTER, 64, 64+16, 1, col);
+}
+
+// Draw game over screen
+void draw_end_screen() {
+    // Draw last game frame
+    draw_game();
+    // Draw GAME OVER
+    riv_draw_text("GAME OVER", RIV_SPRITESHEET_FONT_5X7, RIV_CENTER, 64, 64, 2, RIV_COLOR_RED);
+}
+
+// Called every frame to update game state
+void update() {
+    if (!started) { // Game not started yet
+        // Let game start whenever a key has been pressed
+        if (riv->key_toggle_count > 0) {
+            start_game();
+        }
+    } else if (!ended) { // Game is progressing
+        update_game();
+    }
+}
+
+// Called every frame to draw the game
+void draw() {
+    // Clear screen
+    riv_clear(RIV_COLOR_DARKSLATE);
+    // Draw different screens depending on the game state
+    if (!started) { // Game not started yet
+        draw_start_screen();
+    } else if (!ended) { // Game is progressing
+        draw_game();
+    } else { // Game ended
+        draw_end_screen();
+    }
+}
+
+// Entry point
+int main() {
+    // Set screen size and default frame rate
+    riv->width = 128;
+    riv->height = 128;
+    riv->target_fps = 8;
+    // Main loop, keep presenting frames until user quit or game ends
+    do {
+        // Update game state
+        update();
+        // Draw game graphics
+        draw();
+    } while(riv_present());
+    return 0;
+}