precision highp float;

varying vec4 vertexPosition;

void main(void) {

  vec2 localPos = vec2(mod(vertexPosition.x, 0.1), mod(vertexPosition.y, 0.1));

  float cornerSquareness = 15.0;

  float rss = pow(pow(localPos.x - 0.05, cornerSquareness) + pow(localPos.y - 0.05, cornerSquareness), 1.0 / cornerSquareness);

  vec4 circleColor;

  if (rss < 0.04) {

    circleColor = vec4(1.0, 1.0, 1.0, 1.0);

  } else {

    circleColor = vec4(0.0, 0.0, 0.0, 1.0);

  }

  gl_FragColor = vec4((1.0 - vertexPosition.y) * circleColor.r, abs(vertexPosition.x) * circleColor.g, abs(vertexPosition.y) * circleColor.b, 1.0);