precision mediump float;

uniform vec2 u_resolution;

float random (vec2 st) {
  return fract(sin(dot(st.xy,
             vec2(12.9898,78.233)))*
    43758.5453123);
}

void main() {
  vec2 st = gl_FragCoord.xy/u_resolution.xy;

  float rnd = random( st );

  gl_FragColor = vec4(vec3(rnd),0.05);
}