initial commit with demo in main.c

src/engine/engine.c

@@ -0,0 +1,59 @@
+#include "engine.h"
+
+engine_internal_state_t *internal_state = NULL;
+game_state_t *game_state = NULL;
+
+void
+engine_start() {
+	// main game loop
+	while(game_state->is_running) {
+		uint64_t start = SDL_GetPerformanceCounter();
+
+		// poll events
+		while (SDL_PollEvent(&game_state->event)) {
+			internal_state->engine_poll_events();
+		}
+
+		// call the user-defined framebuffer manipulation function
+		internal_state->engine_update_framebuffer();
+
+		// update the texture with the modified framebuffer
+		SDL_UpdateTexture(
+			internal_state->sdl_state->texture, 
+			NULL, game_state->framebuffer, 
+			internal_state->sdl_state->width * sizeof(uint32_t)
+		);
+
+		SDL_RenderClear(
+			internal_state->sdl_state->renderer
+		);
+
+		SDL_RenderTexture(
+			internal_state->sdl_state->renderer, 
+			internal_state->sdl_state->texture, 
+			NULL, NULL
+		);
+		
+		SDL_RenderPresent(
+			internal_state->sdl_state->renderer
+		);
+
+		uint64_t end = SDL_GetPerformanceCounter();
+
+		double elapsed = 
+			(double)(end - start) / 
+			(double)SDL_GetPerformanceFrequency();
+
+		// cap the framerate at '1.0/TARGET_FRAME' fps
+		if (elapsed < TARGET_FRAME) {
+			SDL_Delay((TARGET_FRAME - elapsed) * 1000);
+		}
+	}
+}
+
+void
+engine_stop() {
+	engine_sdl_destroy(internal_state->sdl_state);
+	free(internal_state);
+	free(game_state);
+}