Initial commit

src/engine/core.c

@@ -0,0 +1,177 @@
+#include "engine/core.h"
+#include "engine/input.h"
+#include "engine/renderer.h"
+#include "engine/audio.h"
+#include "engine/assets.h"
+#include <stdio.h>
+
+#ifdef __EMSCRIPTEN__
+#include <emscripten.h>
+#endif
+
+Engine g_engine = {0};
+
+static GameCallbacks s_callbacks = {0};
+
+void engine_set_callbacks(GameCallbacks cb) {
+    s_callbacks = cb;
+}
+
+bool engine_init(void) {
+    if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_GAMECONTROLLER) != 0) {
+        fprintf(stderr, "SDL_Init failed: %s\n", SDL_GetError());
+        return false;
+    }
+
+    int win_w = SCREEN_WIDTH * WINDOW_SCALE;
+    int win_h = SCREEN_HEIGHT * WINDOW_SCALE;
+
+    g_engine.window = SDL_CreateWindow(
+        WINDOW_TITLE,
+        SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
+        win_w, win_h,
+        SDL_WINDOW_SHOWN
+    );
+    if (!g_engine.window) {
+        fprintf(stderr, "SDL_CreateWindow failed: %s\n", SDL_GetError());
+        return false;
+    }
+
+    g_engine.renderer = SDL_CreateRenderer(
+        g_engine.window, -1,
+        SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC
+    );
+    if (!g_engine.renderer) {
+        fprintf(stderr, "SDL_CreateRenderer failed: %s\n", SDL_GetError());
+        return false;
+    }
+
+    /* Set logical size for pixel-perfect scaling */
+    SDL_RenderSetLogicalSize(g_engine.renderer, SCREEN_WIDTH, SCREEN_HEIGHT);
+    SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "0"); /* nearest neighbor */
+
+    /* Initialize subsystems */
+    input_init();
+    renderer_init(g_engine.renderer);
+    audio_init();
+    assets_init(g_engine.renderer);
+
+    g_engine.running = true;
+    g_engine.tick = 0;
+    g_engine.fps = 0.0f;
+
+    printf("Engine initialized: %dx%d (x%d scale)\n",
+           SCREEN_WIDTH, SCREEN_HEIGHT, WINDOW_SCALE);
+
+    return true;
+}
+
+/* ── Frame-loop state (file-scope so engine_frame can access it) ── */
+static uint64_t s_freq;
+static uint64_t s_prev_time;
+static float    s_accumulator;
+static float    s_fps_timer;
+static int      s_fps_frames;
+
+/*
+ * engine_frame -- execute exactly one iteration of the game loop.
+ *
+ * Called repeatedly by the platform layer:
+ *   Native  : tight while-loop in engine_run()
+ *   Browser : emscripten_set_main_loop() via requestAnimationFrame
+ */
+static void engine_frame(void) {
+    uint64_t current_time = SDL_GetPerformanceCounter();
+    float frame_time = (float)(current_time - s_prev_time) / (float)s_freq;
+    s_prev_time = current_time;
+
+    /* Clamp frame time to avoid spiral of death */
+    if (frame_time > MAX_FRAME_SKIP * DT) {
+        frame_time = MAX_FRAME_SKIP * DT;
+    }
+
+    /* FPS counter */
+    s_fps_timer += frame_time;
+    s_fps_frames++;
+    if (s_fps_timer >= 1.0f) {
+        g_engine.fps = (float)s_fps_frames / s_fps_timer;
+        s_fps_timer = 0.0f;
+        s_fps_frames = 0;
+    }
+
+    /* ── Input ────────────────────────────── */
+    input_poll();
+    if (input_quit_requested()) {
+        g_engine.running = false;
+#ifdef __EMSCRIPTEN__
+        if (s_callbacks.shutdown) {
+            s_callbacks.shutdown();
+        }
+        emscripten_cancel_main_loop();
+#endif
+        return;
+    }
+
+    /* ── Fixed timestep update ────────────── */
+    s_accumulator += frame_time;
+    while (s_accumulator >= DT) {
+        if (s_callbacks.update) {
+            s_callbacks.update(DT);
+        }
+        input_consume();
+        g_engine.tick++;
+        s_accumulator -= DT;
+    }
+
+    /* ── Render ───────────────────────────── */
+    g_engine.interpolation = s_accumulator / DT;
+    renderer_clear();
+    if (s_callbacks.render) {
+        s_callbacks.render(g_engine.interpolation);
+    }
+    renderer_present();
+}
+
+void engine_run(void) {
+    if (s_callbacks.init) {
+        s_callbacks.init();
+    }
+
+    /* Initialise frame-loop timing state */
+    s_freq       = SDL_GetPerformanceFrequency();
+    s_prev_time  = SDL_GetPerformanceCounter();
+    s_accumulator = 0.0f;
+    s_fps_timer  = 0.0f;
+    s_fps_frames = 0;
+
+#ifdef __EMSCRIPTEN__
+    /*
+     * Hand control to the browser's requestAnimationFrame loop.
+     * fps=0  : match display refresh rate
+     * simulate_infinite_loop=1 : don't return from this function
+     *   (so the rest of engine_run never executes until shutdown)
+     */
+    emscripten_set_main_loop(engine_frame, 0, 1);
+#else
+    while (g_engine.running) {
+        engine_frame();
+    }
+#endif
+
+    if (s_callbacks.shutdown) {
+        s_callbacks.shutdown();
+    }
+}
+
+void engine_shutdown(void) {
+    assets_free_all();
+    audio_shutdown();
+    renderer_shutdown();
+    input_shutdown();
+
+    if (g_engine.renderer) SDL_DestroyRenderer(g_engine.renderer);
+    if (g_engine.window)   SDL_DestroyWindow(g_engine.window);
+    SDL_Quit();
+
+    printf("Engine shut down cleanly.\n");
+}