镜像与万花筒：折叠坐标

void main() {
  vec2 p = (gl_FragCoord.xy - 0.5 * uResolution) / min(uResolution.x, uResolution.y);
  float d = min(length(p - vec2(0.25, 0.04)) - 0.05,
                max(abs(p.x - 0.11), abs(p.y - 0.03)) - 0.025);   // 只画一个小圆和一个小方块
  float ink = 1.0 - smoothstep(0.0, fwidth(d), d);
  vec3 color = mix(vec3(0.06, 0.10, 0.14), vec3(0.96, 0.43, 0.30), ink);
  gl_FragColor = vec4(color, 1.0);
}