void
cool_effect(rgb canvas[])
{
    draw_line(canvas,
              WHITE,
              (vec2) {
                  cos(SDL_GetTicks()*0.001) * 300 + W/2,
                  sin(SDL_GetTicks()*0.001) * 300 + H/2,
              },
              (vec2) {
                  W/2,
                  H/2
              });

    draw_line(canvas,
              WHITE,
              (vec2) {
                  cos(SDL_GetTicks()*0.001+1.333*PI) * 300 + W/2,
                  sin(SDL_GetTicks()*0.001+1.333*PI) * 300 + H/2,
              },
              (vec2) {
                  W/2,
                  H/2
              });

    draw_line(canvas,
              WHITE,
              (vec2) {
                  cos(SDL_GetTicks()*0.001+0.667*PI) * 300 + W/2,
                  sin(SDL_GetTicks()*0.001+0.667*PI) * 300 + H/2,
              },
              (vec2) {
                  W/2,
                  H/2
              });


    /* vec2 a = {0, 100}, b = {200, 0}, c = {200, 200}; */
    vec2 a = {
        cos(SDL_GetTicks()*0.001) * 300 + W/2,
        sin(SDL_GetTicks()*0.001) * 300 + H/2
    };
    vec2 b = {
        cos(SDL_GetTicks()*0.001+0.667*PI) * 300 + W/2,
        sin(SDL_GetTicks()*0.001+0.667*PI) * 300 + H/2
    };
    vec2 c = {
        cos(SDL_GetTicks()*0.001+1.333*PI) * 300 + W/2,
        sin(SDL_GetTicks()*0.001+1.333*PI) * 300 + H/2,
    };
    for (int i = 0; i < 10; i++) {
        fill_triangle(canvas, i % 2 ? BLACK : WHITE, (triangle2){a, b, c});
        vec2 tmp_a = midpoint(a, b);
        vec2 tmp_b = midpoint(b, c);
        vec2 tmp_c = midpoint(c, a);
        a = tmp_a;
        b = tmp_b;
        c = tmp_c;
    }
}