第 7 课：SDF Combination

实现

uniform vec2 iResolution;

const vec3 shapeColor      = vec3(1.0, 0.3, 0.3);
const vec3 backgroundColor = vec3(0.12);

float sdfCircle(vec2 center, float r, vec2 pos) {
  return distance(center, pos) - r;
}

void main() {
  vec2 uv = gl_FragCoord.xy;

  float r  = iResolution.y * 0.2;

  vec2 center1 = iResolution * vec2(0.5, 0.4) + vec2(+r, +r);
  vec2 center2 = iResolution * vec2(0.5, 0.4) + vec2(-r, +r);
  vec2 center3 = iResolution * vec2(0.5, 0.4) + vec2(-r, -r);
  vec2 center4 = iResolution * vec2(0.5, 0.4) + vec2(+r, -r);
  vec2 center5 = iResolution * vec2(0.5, 0.4);

  float c1 = sdfCircle(center1, r, uv);
  float c2 = sdfCircle(center2, r, uv);
  float c3 = sdfCircle(center3, r, uv);
  float c4 = sdfCircle(center4, r, uv);
  float c5 = sdfCircle(center5, r, uv);

  //liang yuan min(c1,c2)
  // max(min(c1,c2),-min(c3,c4))
  float t = max(min(min(c1,c2),c5),-min(c3,c4)); // aggregation result
  t = clamp(t, 0.0, 1.0);

  gl_FragColor = vec4(mix(shapeColor, backgroundColor, t), 1.0);
}