precision mediump float;
varying vec4 _color;

void main() {
  vec2 center = vec2(0.5);
  vec2 uv = gl_PointCoord.xy - center;
  float smoothing = 0.005;
  vec4 _color1 = vec4(_color[0], _color[1], _color[2], _color[3]);
  float radius1 = 0.3;
  vec4 _color2 = vec4(_color[0], _color[1], _color[2], _color[3]);
  float radius2 = 0.5;
  float dist = length(uv);

  //SMOOTH
  float gamma = 2.2;
  color1.rgb = pow(_color1.rgb, vec3(gamma));
  color2.rgb = pow(_color2.rgb, vec3(gamma));

  vec4 puck = mix(
    mix(
      _color1,
      _color2,
      smoothstep(
        radius1 - smoothing,
        radius1 + smoothing,
        dist
      )
    ),
    vec4(0,0,0,0),
      smoothstep(
        radius2 - smoothing,
        radius2 + smoothing,
        dist
    )
  );

  //Gamma correction (prevents color fringes)
  puck.rgb = pow(puck.rgb, vec3(1.0 / gamma));
  gl_FragColor = puck;
}