precision mediump float;

#endif

​

uniform vec2 u_resolution;

​

float rectShape(vec2 position, vec2 scale){

  scale = vec2(0.5) - scale * 0.5;

  vec2 shaper = vec2(step(scale.x, position.x), step(scale.y, position.y));

  shaper *= vec2(step(scale.x, 1.0 - position.x), step(scale.y, 1.0 - position.y));

  return shaper.x * shaper.y;

}

​

void main() {

  vec2 position = gl_FragCoord.xy/u_resolution.xy;

  vec3 color = vec3(0.0);

  float rectangle = rectShape(position, vec2(0.6, 0.9));

  color = vec3(rectangle);

  gl_FragColor = vec4(color, 1.0);

}