precision mediump float;

#endif

​

const float PI = 3.1415926535;

​

uniform vec2 u_resolution;

​

float polygonShape(vec2 position, float radius, float sides){

  position = position * 2.0 - 1.0;

  float angle = atan(position.x, position.y);

  float slice = PI * 2.0 / sides;

  return step(radius, cos(floor(0.5 + angle / slice) * slice - angle) * length(position));

}

​

void main() {

  vec2 position = gl_FragCoord.xy/u_resolution;

  vec3 color = vec3(0.0);

  float polygon = polygonShape(position, 0.7, 6.0);

  color = vec3(polygon);

  gl_FragColor = vec4(color, 1.0);

}