​

varying vec2 pos;

​

const int num_circles = 100;

uniform vec3 circles[num_circles];

​

void main() {

  // Single circle SDF

  vec3 circle = vec3(0.5, 0.5, 0.3);

  float d = length(pos - circle.xy) - circle.z;

  // Sharp circle

  // d = step(0., d);

  // Smooth circle

  d = smoothstep(0., 0.01, d);

  gl_FragColor = vec4(d, d, d, 1.);

  // Multi circle SDF

  // float colour = 1.;

  // for(int i = 0; i < num_circles; i ++) {

  //   float d = length(pos - circles[i].xy) - circles[i].z;

  //   d = step(0., d);

  //   colour *= d;

  // }

​

  // gl_FragColor = vec4(colour, colour, colour, 1.);

}