Ghosts

ghosts.html

<style>
body {
  margin: 0;
  padding: 0;
}

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

</style>

<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_buffer;
  uniform bool u_renderpass;
    
  const float blurMultiplier = 0.98;
  const float circleSize = .25;
  const float blurStrength = .6;
  const float threshold = .5;
  const float scale = 3.;
  
  #define PI 3.141592653589793
  #define TAU 6.283185307179586

  vec2 hash2(vec2 p)
  {
    vec2 o = texture2D( u_noise, (p+0.5)/256.0, -100.0 ).xy;
    return o;
  }
  
  vec3 hsb2rgb( in vec3 c ){
    vec3 rgb = clamp(abs(mod(c.x*6.0+vec3(0.0,4.0,2.0),
                             6.0)-3.0)-1.0,
                     0.0,
                     1.0 );
    rgb = rgb*rgb*(3.0-2.0*rgb);
    return c.z * mix( vec3(1.0), rgb, c.y);
  }
  
  vec3 domain(vec2 z){
    return vec3(hsb2rgb(vec3(atan(z.y,z.x)/TAU,1.,1.)));
  }
  vec3 colour(vec2 z) {
      return domain(z);
  }

  
#define pow2(x) (x * x)

const int samples = 8;
const float sigma = float(samples) * 0.25;

float gaussian(vec2 i) {
    return 1.0 / (2.0 * PI * pow2(sigma)) * exp(-((pow2(i.x) + pow2(i.y)) / (2.0 * pow2(sigma))));
}

vec3 blur(sampler2D sp, vec2 uv, vec2 scale) {
    vec3 col = vec3(0.0);
    float accum = 0.0;
    float weight;
    vec2 offset;
    
    for (int x = -samples / 2; x < samples / 2; ++x) {
        for (int y = -samples / 2; y < samples / 2; ++y) {
            offset = vec2(x, y);
            weight = gaussian(offset);
            col += texture2D(sp, uv + scale * offset).rgb * weight;
            accum += weight;
        }
    }
    
    return col / accum;
}
  void main() {
    vec2 uv = (gl_FragCoord.xy - 0.5 * u_resolution.xy) / u_resolution.y;
    uv *= scale;
    vec2 mouse = u_mouse * scale;
    
    vec2 ps = vec2(1.0) / u_resolution.xy;
    vec2 sample = gl_FragCoord.xy / u_resolution.xy;
    // vec2 o = vec2(.5);
    // float d = 1.05;
    // sample = d * (sample - o);
    // sample += o;
    sample += vec2(sin((u_time+uv.y)*10.)*.002, -.008);
    
    vec3 fragcolour;
    vec4 tex;
    if(u_renderpass) {
      tex = vec4(blur(u_buffer, sample, ps*blurStrength) * blurMultiplier, 1.);
      float df = length(mouse - uv);
      fragcolour = vec3( smoothstep( circleSize, 0., df ) );
    } else {
      tex = texture2D(u_buffer, sample, 2.) * .98;
      tex = smoothstep(threshold - fwidth(tex.x), threshold, tex);
    }
    // vec4 tex = texture2D(u_buffer, sample, 2.) * .98;
    
    

    gl_FragColor = vec4(fragcolour,1.0);
    gl_FragColor += tex;
    
  }
</script>

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

<script>

/*
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, rtTexture, rtTexture2;
loader.setCrossOrigin("anonymous");
loader.load(
"https://s3-us-west-2.amazonaws.com/s.cdpn.io/982762/noise.png",
function do_something_with_texture(tex) {
  texture = tex;
  texture.wrapS = THREE.RepeatWrapping;
  texture.wrapT = THREE.RepeatWrapping;
  texture.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);

  rtTexture = new THREE.WebGLRenderTarget(
  window.innerWidth * 0.2,
  window.innerHeight * 0.2);

  rtTexture2 = new THREE.WebGLRenderTarget(
  window.innerWidth * 0.2,
  window.innerHeight * 0.2);


  uniforms = {
    u_time: { type: "f", value: 1.0 },
    u_resolution: { type: "v2", value: new THREE.Vector2() },
    u_noise: { type: "t", value: texture },
    u_buffer: { type: "t", value: rtTexture.texture },
    u_mouse: { type: "v2", value: new THREE.Vector2() },
    u_renderpass: { type: "b", value: false } };


  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;

  rtTexture = new THREE.WebGLRenderTarget(
  window.innerWidth * 0.2,
  window.innerHeight * 0.2);

  rtTexture2 = new THREE.WebGLRenderTarget(
  window.innerWidth * 0.2,
  window.innerHeight * 0.2);

}

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 renderTexture(delta) {
  // let ov = uniforms.u_buff.value;

  let odims = uniforms.u_resolution.value.clone();
  uniforms.u_resolution.value.x = window.innerWidth * 0.2;
  uniforms.u_resolution.value.y = window.innerHeight * 0.2;

  uniforms.u_buffer.value = rtTexture2.texture;

  uniforms.u_renderpass.value = true;

  //   rtTexture = rtTexture2;
  //   rtTexture2 = buffer;

  window.rtTexture = rtTexture;
  renderer.setRenderTarget(rtTexture);
  renderer.render(scene, camera, rtTexture, true);

  let buffer = rtTexture;
  rtTexture = rtTexture2;
  rtTexture2 = buffer;

  // uniforms.u_buff.value = ov;

  uniforms.u_buffer.value = rtTexture.texture;
  uniforms.u_resolution.value = odims;
  uniforms.u_renderpass.value = false;
}
function render(delta) {
  uniforms.u_time.value = delta * 0.0005;
  renderer.render(scene, camera);
  renderTexture();

  if (capturing) {
    capturer.capture(renderer.domElement);
  }
}
</script>