the-simian/slush-phaser-webpack

#ifdef GL_ES
precision mediump float;
#endif

uniform float time;
uniform vec2 mouse;
uniform vec2 resolution;

void main( void ) {
    float treshhold = 200.;
    
    vec2 position = gl_FragCoord.xy - mouse.xy * resolution.xy; 
    float rad = sqrt(position.x * position.x + position.y * position.y) ;
    float amp = (treshhold-rad)/treshhold;
    if(amp<0.0){ amp=0.0;}
    float gray = (sin(rad/ 10. - time * 3.)+0.5)*amp;
    gl_FragColor = vec4(gray,gray,gray, 1.0 );
}