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SDL2 framebuffer graphics demo, based on https://wiki.libsdl.org/SDL2/MigrationGuide#if-your-game-just-wants-to-get-fully-rendered-frames-to-the-screen
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| /* | |
| gcc main.c -o main -O3 -lSDL2 | |
| This hits 240fps at 4K resolution, on my M1 Pro | |
| */ | |
| #include <SDL2/SDL.h> | |
| #include <stdio.h> | |
| #define FB_WIDTH 3840 | |
| #define FB_HEIGHT 2160 | |
| #define FPS_AVG_WINDOW 32 | |
| /* | |
| fb is an FB_WIDTH*FB_HEIGHT array of ARGB8888 Uint32s | |
| if your value of FB_WIDTH isn't a round number, you might want to mess around | |
| with different strides | |
| */ | |
| void render(Uint32 *fb, Uint32 ticks) | |
| { | |
| for (int y=0; y<FB_HEIGHT; y++) { | |
| for (int x=0; x<FB_WIDTH; x++) { | |
| Uint32 val = ((x-ticks/4)^(y-ticks/4)) & 0xff; // moving xor texture | |
| fb[y*FB_WIDTH+x] = 0xff000000 | (val << 16) | (val << 8) | val; // pack into ARGB8888 | |
| } | |
| } | |
| } | |
| int main(int argc, char* argv[]) | |
| { | |
| SDL_Window* window = NULL; | |
| SDL_Renderer *renderer = NULL; | |
| SDL_Texture *texture = NULL; | |
| if (SDL_Init(SDL_INIT_VIDEO) < 0) { | |
| SDL_Log("Could not init SDL2: %s", SDL_GetError()); | |
| return -1; | |
| } | |
| // create window | |
| window = SDL_CreateWindow( | |
| "SDL2 Framebuffer Test", | |
| SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, | |
| FB_WIDTH, FB_HEIGHT, | |
| SDL_WINDOW_SHOWN | |
| ); | |
| if (window == NULL) { | |
| SDL_Log("Could not create window: %s", SDL_GetError()); | |
| return -1; | |
| } | |
| // create renderer | |
| renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED); | |
| if (renderer == NULL) { | |
| SDL_Log("Could not create renderer: %s", SDL_GetError()); | |
| return -1; | |
| } | |
| // create texture | |
| texture = SDL_CreateTexture( | |
| renderer, | |
| SDL_PIXELFORMAT_ARGB8888, | |
| SDL_TEXTUREACCESS_STREAMING, | |
| FB_WIDTH, FB_HEIGHT | |
| ); | |
| if (texture == NULL) { | |
| SDL_Log("Could not create texture: %s", SDL_GetError()); | |
| return -1; | |
| } | |
| Uint32 *fb = malloc(FB_WIDTH * FB_HEIGHT * sizeof(Uint32)); | |
| if (fb == NULL) { | |
| perror("fb malloc"); | |
| return -1; | |
| } | |
| Uint32 prev_ticks[32] = {0}; | |
| size_t prev_ticks_idx = 0; | |
| for (;;) { | |
| // drain SDL event queue | |
| SDL_Event event; | |
| while (SDL_PollEvent(&event)) { | |
| if (event.type == SDL_QUIT) { | |
| goto cleanup; | |
| } | |
| } | |
| // do the rendering work | |
| Uint32 tick_before = SDL_GetTicks(); | |
| render(fb, tick_before); | |
| Uint32 tick_after = SDL_GetTicks(); | |
| // calculate average FPS over the previous FPS_AVG_WINDOW frames | |
| int fps_delta = (int)tick_before - prev_ticks[prev_ticks_idx]; | |
| prev_ticks[prev_ticks_idx] = tick_before; | |
| prev_ticks_idx = (prev_ticks_idx + 1) % FPS_AVG_WINDOW; | |
| SDL_Log( | |
| "Rendered %ux%u pixels in %dms (%.1f fps avg)", | |
| FB_WIDTH, FB_HEIGHT, | |
| (int)tick_after-tick_before, | |
| (1000.0 * FPS_AVG_WINDOW) / fps_delta | |
| ); | |
| // send the texture to the GPU | |
| SDL_UpdateTexture( | |
| texture, | |
| NULL /* rect to update (NULL defaults to whole texture) */, | |
| fb, | |
| FB_WIDTH * sizeof(Uint32) /* pitch (aka stride) */ | |
| ); | |
| SDL_RenderClear(renderer); | |
| SDL_RenderCopy(renderer, texture, NULL, NULL); | |
| SDL_RenderPresent(renderer); | |
| } | |
| cleanup: | |
| SDL_DestroyTexture(texture); | |
| SDL_DestroyRenderer(renderer); | |
| SDL_DestroyWindow(window); | |
| SDL_Quit(); | |
| return 0; | |
| } |
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