<script src="https://cdnjs.cloudflare.com/ajax/libs/three.js/88/three.min.js"></script>
<script id="vertexShader" type="x-shader/x-vertex">
    void main() {
        gl_Position = vec4( position, 1.0 );
    }
</script>
<script id="fragmentShader" type="x-shader/x-fragment">
  uniform vec2 u_resolution;
  uniform vec2 u_mouse;
  uniform float u_time;
  uniform sampler2D u_noise;
  uniform sampler2D u_bg;
  uniform float u_scroll;
  
  const vec3 cloudcolour = vec3(.07,0.0,.24);
  const vec3 lightcolour = vec3(.25,0.6,1.);
  
  float mod289(float x){return x - floor(x * (1.0 / 289.0)) * 289.0;}
  vec4 mod289(vec4 x){return x - floor(x * (1.0 / 289.0)) * 289.0;}
  vec4 perm(vec4 x){return mod289(((x * 34.0) + 1.0) * x);}

  float noise(vec3 p){
      vec3 a = floor(p);
      vec3 d = p - a;
      d = d * d * (3.0 - 2.0 * d);

      vec4 b = a.xxyy + vec4(0.0, 1.0, 0.0, 1.0);
      vec4 k1 = perm(b.xyxy);
      vec4 k2 = perm(k1.xyxy + b.zzww);

      vec4 c = k2 + a.zzzz;
      vec4 k3 = perm(c);
      vec4 k4 = perm(c + 1.0);

      vec4 o1 = fract(k3 * (1.0 / 41.0));
      vec4 o2 = fract(k4 * (1.0 / 41.0));

      vec4 o3 = o2 * d.z + o1 * (1.0 - d.z);
      vec2 o4 = o3.yw * d.x + o3.xz * (1.0 - d.x);

      return o4.y * d.y + o4.x * (1.0 - d.y);
  }

  void main() {
    vec2 uv = (gl_FragCoord.xy - 0.5 * u_resolution.xy) / min(u_resolution.y, u_resolution.x);
    
    float noise1 = noise(vec3(uv * 3. * noise(vec3(uv * 3. + 100., u_time * 3. + 10.)), u_time * 2.))  * 2.;
    
    float noise2 = noise(vec3(uv + 2.35, u_time * 1.357 - 10.));
    
    uv.y -= u_scroll * .0001;
    
    uv += texture2D(u_bg, uv * vec2(.5, 1.) - vec2(u_time * .05, 1.) - .5 * .05).rg * 0.08 + noise1 * .008 * (1. - clamp(noise1 * noise1 * 2. + .2, 0., 1.));
    
    vec3 tex = texture2D(u_bg, uv * vec2(.5, 1.) - vec2(u_time * .02, 1.) - .5).rgb;
    
    uv.y -= u_scroll * .0001;
    vec3 tex1 = texture2D(u_bg, uv * vec2(.5, 1.) - vec2(u_time * .08, 1.)).rgb;
    
    uv.y -= u_scroll * .0001;
    vec3 tex2 = texture2D(u_bg, (uv * .8 + .5) * vec2(.5, 1.) - vec2(u_time * .1, 1.)).rgb;
    
    vec3 fragcolour = tex;
    
    float shade = tex.r;
    shade *= clamp(noise1 * noise2 * sin(u_time * 3.), .2, 10.);
    shade += shade * shade * 3.;
    shade -= (1. - clamp(tex1 * 4., 0., 1.).r) * .2;
    shade -= (1. - clamp(tex2 * 4., 0., 1.).r) * .1;
    
    fragcolour = mix(cloudcolour, lightcolour, shade);

    gl_FragColor = vec4(fragcolour, 1.);
  }
</script>


<div id="container" touch-action="none"></div>

body {
  height: 10000px;
  margin: 0;
  padding: 0;
}

#container {
  position: fixed;
  touch-action: none;
}

/*
Most of the stuff in here is just bootstrapping. Essentially it's just
setting ThreeJS up so that it renders a flat surface upon which to draw 
the shader. The only thing to see here really is the uniforms sent to 
the shader. Apart from that all of the magic happens in the HTML view
under the fragment shader.
*/

let container;
let camera, scene, renderer;
let uniforms;

let loader=new THREE.TextureLoader();
let texture, bg;
loader.setCrossOrigin("anonymous");
loader.load(
  'https://s3-us-west-2.amazonaws.com/s.cdpn.io/982762/noise.png',
  (tex) => {
    texture = tex;
    texture.wrapS = THREE.RepeatWrapping;
    texture.wrapT = THREE.RepeatWrapping;
    texture.minFilter = THREE.LinearFilter;
    loader.load(
      'https://s3-us-west-2.amazonaws.com/s.cdpn.io/982762/clouds-1-tile.jpg',
      (tex) => {
        bg = tex;
        bg.wrapS = THREE.RepeatWrapping;
        bg.wrapT = THREE.RepeatWrapping;
        bg.minFilter = THREE.LinearFilter;
        init();
        animate();
      }
    );
  }
);

function init() {
  container = document.getElementById( 'container' );

  camera = new THREE.Camera();
  camera.position.z = 1;

  scene = new THREE.Scene();

  var geometry = new THREE.PlaneBufferGeometry( 2, 2 );

  uniforms = {
    u_time: { type: "f", value: 1.0 },
    u_resolution: { type: "v2", value: new THREE.Vector2() },
    u_noise: { type: "t", value: texture },
    u_bg: { type: "t", value: bg },
    u_mouse: { type: "v2", value: new THREE.Vector2() },
    u_scroll: { type: 'f', value : 0 }
  };

  var material = new THREE.ShaderMaterial( {
    uniforms: uniforms,
    vertexShader: document.getElementById( 'vertexShader' ).textContent,
    fragmentShader: document.getElementById( 'fragmentShader' ).textContent
  } );
  material.extensions.derivatives = true;

  var mesh = new THREE.Mesh( geometry, material );
  scene.add( mesh );

  renderer = new THREE.WebGLRenderer();
  renderer.setPixelRatio( window.devicePixelRatio );

  container.appendChild( renderer.domElement );

  onWindowResize();
  window.addEventListener( 'resize', onWindowResize, false );

  document.addEventListener('pointermove', (e)=> {
    let ratio = window.innerHeight / window.innerWidth;
    uniforms.u_mouse.value.x = (e.pageX - window.innerWidth / 2) / window.innerWidth / ratio;
    uniforms.u_mouse.value.y = (e.pageY - window.innerHeight / 2) / window.innerHeight * -1;
    
    e.preventDefault();
  });
}

function onWindowResize( event ) {
  renderer.setSize( window.innerWidth, window.innerHeight );
  uniforms.u_resolution.value.x = renderer.domElement.width;
  uniforms.u_resolution.value.y = renderer.domElement.height;
}

function animate(delta) {
  requestAnimationFrame( animate );
  render(delta);
}






let capturer = new CCapture( { 
  verbose: true, 
  framerate: 60,
  // motionBlurFrames: 4,
  quality: 90,
  format: 'webm',
  workersPath: 'js/'
 } );
let capturing = false;

isCapturing = function(val) {
  if(val === false && window.capturing === true) {
    capturer.stop();
    capturer.save();
  } else if(val === true && window.capturing === false) {
    capturer.start();
  }
  capturing = val;
}
toggleCapture = function() {
  isCapturing(!capturing);
}

window.addEventListener('keyup', function(e) { if(e.keyCode == 68) toggleCapture(); });

let then = 0;
function render(delta) {
  
  uniforms.u_time.value = -1000 + delta * 0.0005;
  uniforms.u_scroll.value = window.scrollY;
  renderer.render( scene, camera );
  
  if(capturing) {
    capturer.capture( renderer.domElement );
  }
}