gistfile1.txt

#include <stdio.h>
#include <SDL2/SDL.h>

unsigned int frames = 0;
unsigned int t_acc = 0;
 
SDL_Window *window;
SDL_Surface *surface;
SDL_Renderer *renderer;

SDL_Point points[320 * 240];

void print_fps ()
{
    static Uint32 last_t = 0;
    Uint32 t = SDL_GetTicks();
    Uint32 dt = t - last_t;
    t_acc += dt;
    if (t_acc > 1000)
    {
	unsigned int el_time = t_acc / 1000;
	printf("- fps: %g\n",
		(float) frames / (float) el_time);
	t_acc = 0;
	frames = 0;
    }
    last_t = t;
}

void blit_noise()
{
    unsigned int i, j, count;
    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 0);
    SDL_RenderClear(renderer);
    SDL_SetRenderDrawColor(renderer, 255, 255, 255, 0);
    count = 0;
    for (i=0; i < surface->w; ++i) {
	for (j=0; j < surface->h; ++j) {
	    if (rand() & 1) {
		SDL_Point p = { i, j };
		points[count++] = p;
	    }
	}
    }
    SDL_RenderDrawPoints(renderer, points, count);
    SDL_RenderPresent(renderer);
    ++frames;
    print_fps();
}

int main(int argc, char *argv[]) {
    int i;
    printf("initializing SDL... %d\n",
	    SDL_Init(SDL_INIT_TIMER | SDL_INIT_VIDEO)
	  );
    window = SDL_CreateWindow(
	    "my window",
	    0, 0,
	    320, 240,
	    SDL_WINDOW_SHOWN
	    );
    renderer = SDL_CreateRenderer(window, -1, 0);
    surface = SDL_GetWindowSurface(window);

    int pixelformat = SDL_GetWindowPixelFormat(window);
    printf("pixel format is %x\n", pixelformat);
    printf("pixel type is %x\n", SDL_PIXELTYPE(pixelformat));
    printf("pixel order is %x\n", SDL_PIXELORDER(pixelformat));
    printf("pixel layout is %x\n", SDL_PIXELLAYOUT(pixelformat));
    printf("%d bits per pixel\n", SDL_BITSPERPIXEL(pixelformat));
    printf("%d bytes per pixel\n", SDL_BYTESPERPIXEL(pixelformat));
    printf("%s a palette\n", SDL_ISPIXELFORMAT_INDEXED(pixelformat) ? "has" : "does not have");

    for (i=0;i<100;i++) {
	blit_noise();
    }
    SDL_Quit();
    return 0;
}