simple PPM output

ppm.c

static void
write_header(FILE *out, int width, int height, int max_color_val)
{
    fprintf(out, "P3\n%d %d\n%d\n", height, width, max_color_val);
}

static void
write_color_val(FILE *out, int red, int green, int blue)
{
    fprintf(out, "%d %d %d\n", red, green, blue);
}

static void
write_image(FILE *out, int *image, int width, int height)
{    
    int i;
    for(i=0; i<width*height; i++)
    {
        int color = image[i];
        write_color_val(out, color&0xff, (color>>8)&0xff, (color>>16)&0xff);
    }
}

void
write_to_file(char *filename, int *image, int width, int height)
{
    FILE *fout = fopen(filename, "w");
    write_header(fout, width, height, 256);
    write_image(fout, image, width, height);
    fclose(fout);
}