'Gerakkan tetikus, lihat keajaiban' (CSS, JS)

Demo

Gerakkan tetikus

  Lihat  keajaiban

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<div class="labu"><section id='container'>
  <h1 class='a-title'>Gerakkan tetikus</h1>
  <h2 class='a-second-title'>&nbsp; Lihat&nbsp; keajaiban</h2>
  <canvas></canvas>
</section>
</div>
<style>  
.labu {
  margin: 0;  
  width: 100%;
  height: 86vh;
}
#container {
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 100%;
  height: 100%;
}
.a-title {
  position: absolute;
  color: transparent;
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-image: conic-gradient(#ed0101, blue);
  pointer-events: none;
  mix-blend-mode: difference;
  filter: drop-shadow(2px 4px 6px black);
}
.a-second-title {
  position: absolute;
  margin-top: 25vh;
  pointer-events: none;
  -webkit-text-stroke: 1.3px white;
  letter-spacing: 1px;
  font-size: -webkit-xxx-large;
  font-weight: 900;
  mix-blend-mode: color-dodge;
}
canvas {
  width: 100%;
  height: 100%;
}
</style>
<script>
  'use strict';
const canvas = document.getElementsByTagName('canvas')[0];
canvas.width = canvas.clientWidth;
canvas.height = canvas.clientHeight;
let config = {
  TEXTURE_DOWNSAMPLE: 1,
  DENSITY_DISSIPATION: 0.98,
  VELOCITY_DISSIPATION: 0.99,
  PRESSURE_DISSIPATION: 0.8,
  PRESSURE_ITERATIONS: 25,
  CURL: 28,
  SPLAT_RADIUS: 0.004 };
let pointers = [];
let splatStack = [];
const { gl, ext } = getWebGLContext(canvas);
function getWebGLContext(canvas) {
  const params = { alpha: false, depth: false, stencil: false, antialias: false };
  let gl = canvas.getContext('webgl2', params);
  const isWebGL2 = !!gl;
  if (!isWebGL2)
  gl = canvas.getContext('webgl', params) || canvas.getContext('experimental-webgl', params);
  let halfFloat;
  let supportLinearFiltering;
  if (isWebGL2) {
    gl.getExtension('EXT_color_buffer_float');
    supportLinearFiltering = gl.getExtension('OES_texture_float_linear');
  } else {
    halfFloat = gl.getExtension('OES_texture_half_float');
    supportLinearFiltering = gl.getExtension('OES_texture_half_float_linear');
  }
  gl.clearColor(0.0, 0.0, 0.0, 1.0);
  const halfFloatTexType = isWebGL2 ? gl.HALF_FLOAT : halfFloat.HALF_FLOAT_OES;
  let formatRGBA;
  let formatRG;
  let formatR;
  if (isWebGL2)
  {
    formatRGBA = getSupportedFormat(gl, gl.RGBA16F, gl.RGBA, halfFloatTexType);
    formatRG = getSupportedFormat(gl, gl.RG16F, gl.RG, halfFloatTexType);
    formatR = getSupportedFormat(gl, gl.R16F, gl.RED, halfFloatTexType);
  } else
  {
    formatRGBA = getSupportedFormat(gl, gl.RGBA, gl.RGBA, halfFloatTexType);
    formatRG = getSupportedFormat(gl, gl.RGBA, gl.RGBA, halfFloatTexType);
    formatR = getSupportedFormat(gl, gl.RGBA, gl.RGBA, halfFloatTexType);
  }
  return {
    gl,
    ext: {
      formatRGBA,
      formatRG,
      formatR,
      halfFloatTexType,
      supportLinearFiltering } };
}
function getSupportedFormat(gl, internalFormat, format, type)
{
  if (!supportRenderTextureFormat(gl, internalFormat, format, type))
  {
    switch (internalFormat) {
      case gl.R16F:
        return getSupportedFormat(gl, gl.RG16F, gl.RG, type);
      case gl.RG16F:
        return getSupportedFormat(gl, gl.RGBA16F, gl.RGBA, type);
      default:
        return null;}
  }
  return {
    internalFormat,
    format };
}
function supportRenderTextureFormat(gl, internalFormat, format, type) {
  let texture = gl.createTexture();
  gl.bindTexture(gl.TEXTURE_2D, texture);
  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
  gl.texImage2D(gl.TEXTURE_2D, 0, internalFormat, 4, 4, 0, format, type, null);
  let fbo = gl.createFramebuffer();
  gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
  gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, 0);
  const status = gl.checkFramebufferStatus(gl.FRAMEBUFFER);
  if (status != gl.FRAMEBUFFER_COMPLETE)
  return false;
  return true;
}
function pointerPrototype() {
  this.id = -1;
  this.x = 0;
  this.y = 0;
  this.dx = 0;
  this.dy = 0;
  this.down = false;
  this.moved = false;
  this.color = [30, 0, 300];
}
pointers.push(new pointerPrototype());
class GLProgram {
  constructor(vertexShader, fragmentShader) {
    this.uniforms = {};
    this.program = gl.createProgram();
    gl.attachShader(this.program, vertexShader);
    gl.attachShader(this.program, fragmentShader);
    gl.linkProgram(this.program);
    if (!gl.getProgramParameter(this.program, gl.LINK_STATUS))
    throw gl.getProgramInfoLog(this.program);
    const uniformCount = gl.getProgramParameter(this.program, gl.ACTIVE_UNIFORMS);
    for (let i = 0; i < uniformCount; i++) {
      const uniformName = gl.getActiveUniform(this.program, i).name;
      this.uniforms[uniformName] = gl.getUniformLocation(this.program, uniformName);
    }
  }
  bind() {
    gl.useProgram(this.program);
  }}

function compileShader(type, source) {
  const shader = gl.createShader(type);
  gl.shaderSource(shader, source);
  gl.compileShader(shader);
  if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS))
  throw gl.getShaderInfoLog(shader);
  return shader;
};
const baseVertexShader = compileShader(gl.VERTEX_SHADER, `
    precision highp float;
    precision mediump sampler2D;
    attribute vec2 aPosition;
    varying vec2 vUv;
    varying vec2 vL;
    varying vec2 vR;
    varying vec2 vT;
    varying vec2 vB;
    uniform vec2 texelSize;
    void main () {
        vUv = aPosition * 0.5 + 0.5;
        vL = vUv - vec2(texelSize.x, 0.0);
        vR = vUv + vec2(texelSize.x, 0.0);
        vT = vUv + vec2(0.0, texelSize.y);
        vB = vUv - vec2(0.0, texelSize.y);
        gl_Position = vec4(aPosition, 0.0, 1.0);
    }
`);
const clearShader = compileShader(gl.FRAGMENT_SHADER, `
    precision highp float;
    precision mediump sampler2D;
    varying vec2 vUv;
    uniform sampler2D uTexture;
    uniform float value;
    void main () {
        gl_FragColor = value * texture2D(uTexture, vUv);
    }
`);
const displayShader = compileShader(gl.FRAGMENT_SHADER, `
    precision highp float;
    precision mediump sampler2D;
    varying vec2 vUv;
    uniform sampler2D uTexture;
    void main () {
        gl_FragColor = texture2D(uTexture, vUv);
    }
`);
const splatShader = compileShader(gl.FRAGMENT_SHADER, `
    precision highp float;
    precision mediump sampler2D;
    varying vec2 vUv;
    uniform sampler2D uTarget;
    uniform float aspectRatio;
    uniform vec3 color;
    uniform vec2 point;
    uniform float radius;
    void main () {
        vec2 p = vUv - point.xy;
        p.x *= aspectRatio;
        vec3 splat = exp(-dot(p, p) / radius) * color;
        vec3 base = texture2D(uTarget, vUv).xyz;
        gl_FragColor = vec4(base + splat, 1.0);
    }
`);
const advectionManualFilteringShader = compileShader(gl.FRAGMENT_SHADER, `
    precision highp float;
    precision mediump sampler2D;
    varying vec2 vUv;
    uniform sampler2D uVelocity;
    uniform sampler2D uSource;
    uniform vec2 texelSize;
    uniform float dt;
    uniform float dissipation;
    vec4 bilerp (in sampler2D sam, in vec2 p) {
        vec4 st;
        st.xy = floor(p - 0.5) + 0.5;
        st.zw = st.xy + 1.0;
        vec4 uv = st * texelSize.xyxy;
        vec4 a = texture2D(sam, uv.xy);
        vec4 b = texture2D(sam, uv.zy);
        vec4 c = texture2D(sam, uv.xw);
        vec4 d = texture2D(sam, uv.zw);
        vec2 f = p - st.xy;
        return mix(mix(a, b, f.x), mix(c, d, f.x), f.y);
    }
    void main () {
        vec2 coord = gl_FragCoord.xy - dt * texture2D(uVelocity, vUv).xy;
        gl_FragColor = dissipation * bilerp(uSource, coord);
        gl_FragColor.a = 1.0;
    }
`);
const advectionShader = compileShader(gl.FRAGMENT_SHADER, `
    precision highp float;
    precision mediump sampler2D;
    varying vec2 vUv;
    uniform sampler2D uVelocity;
    uniform sampler2D uSource;
    uniform vec2 texelSize;
    uniform float dt;
    uniform float dissipation;
    void main () {
        vec2 coord = vUv - dt * texture2D(uVelocity, vUv).xy * texelSize;
        gl_FragColor = dissipation * texture2D(uSource, coord);
        gl_FragColor.a = 1.0;
    }
`);
const divergenceShader = compileShader(gl.FRAGMENT_SHADER, `
    precision highp float;
    precision mediump sampler2D;
    varying vec2 vUv;
    varying vec2 vL;
    varying vec2 vR;
    varying vec2 vT;
    varying vec2 vB;
    uniform sampler2D uVelocity;
    vec2 sampleVelocity (in vec2 uv) {
        vec2 multiplier = vec2(1.0, 1.0);
        if (uv.x < 0.0) { uv.x = 0.0; multiplier.x = -1.0; }
        if (uv.x > 1.0) { uv.x = 1.0; multiplier.x = -1.0; }
        if (uv.y < 0.0) { uv.y = 0.0; multiplier.y = -1.0; }
        if (uv.y > 1.0) { uv.y = 1.0; multiplier.y = -1.0; }
        return multiplier * texture2D(uVelocity, uv).xy;
    }
    void main () {
        float L = sampleVelocity(vL).x;
        float R = sampleVelocity(vR).x;
        float T = sampleVelocity(vT).y;
        float B = sampleVelocity(vB).y;
        float div = 0.5 * (R - L + T - B);
        gl_FragColor = vec4(div, 0.0, 0.0, 1.0);
    }
`);
const curlShader = compileShader(gl.FRAGMENT_SHADER, `
    precision highp float;
    precision mediump sampler2D;
    varying vec2 vUv;
    varying vec2 vL;
    varying vec2 vR;
    varying vec2 vT;
    varying vec2 vB;
    uniform sampler2D uVelocity;
    void main () {
        float L = texture2D(uVelocity, vL).y;
        float R = texture2D(uVelocity, vR).y;
        float T = texture2D(uVelocity, vT).x;
        float B = texture2D(uVelocity, vB).x;
        float vorticity = R - L - T + B;
        gl_FragColor = vec4(vorticity, 0.0, 0.0, 1.0);
    }
`);
const vorticityShader = compileShader(gl.FRAGMENT_SHADER, `
    precision highp float;
    precision mediump sampler2D;
    varying vec2 vUv;
    varying vec2 vT;
    varying vec2 vB;
    uniform sampler2D uVelocity;
    uniform sampler2D uCurl;
    uniform float curl;
    uniform float dt;
    void main () {
        float T = texture2D(uCurl, vT).x;
        float B = texture2D(uCurl, vB).x;
        float C = texture2D(uCurl, vUv).x;
        vec2 force = vec2(abs(T) - abs(B), 0.0);
        force *= 1.0 / length(force + 0.00001) * curl * C;
        vec2 vel = texture2D(uVelocity, vUv).xy;
        gl_FragColor = vec4(vel + force * dt, 0.0, 1.0);
    }
`);
const pressureShader = compileShader(gl.FRAGMENT_SHADER, `
    precision highp float;
    precision mediump sampler2D;
    varying vec2 vUv;
    varying vec2 vL;
    varying vec2 vR;
    varying vec2 vT;
    varying vec2 vB;
    uniform sampler2D uPressure;
    uniform sampler2D uDivergence;
    vec2 boundary (in vec2 uv) {
        uv = min(max(uv, 0.0), 1.0);
        return uv;
    }
    void main () {
        float L = texture2D(uPressure, boundary(vL)).x;
        float R = texture2D(uPressure, boundary(vR)).x;
        float T = texture2D(uPressure, boundary(vT)).x;
        float B = texture2D(uPressure, boundary(vB)).x;
        float C = texture2D(uPressure, vUv).x;
        float divergence = texture2D(uDivergence, vUv).x;
        float pressure = (L + R + B + T - divergence) * 0.25;
        gl_FragColor = vec4(pressure, 0.0, 0.0, 1.0);
    }
`);
const gradientSubtractShader = compileShader(gl.FRAGMENT_SHADER, `
    precision highp float;
    precision mediump sampler2D;
    varying vec2 vUv;
    varying vec2 vL;
    varying vec2 vR;
    varying vec2 vT;
    varying vec2 vB;
    uniform sampler2D uPressure;
    uniform sampler2D uVelocity;
    vec2 boundary (in vec2 uv) {
        uv = min(max(uv, 0.0), 1.0);
        return uv;
    }
    void main () {
        float L = texture2D(uPressure, boundary(vL)).x;
        float R = texture2D(uPressure, boundary(vR)).x;
        float T = texture2D(uPressure, boundary(vT)).x;
        float B = texture2D(uPressure, boundary(vB)).x;
        vec2 velocity = texture2D(uVelocity, vUv).xy;
        velocity.xy -= vec2(R - L, T - B);
        gl_FragColor = vec4(velocity, 0.0, 1.0);
    }
`);
let textureWidth;
let textureHeight;
let density;
let velocity;
let divergence;
let curl;
let pressure;
initFramebuffers();
const clearProgram = new GLProgram(baseVertexShader, clearShader);
const displayProgram = new GLProgram(baseVertexShader, displayShader);
const splatProgram = new GLProgram(baseVertexShader, splatShader);
const advectionProgram = new GLProgram(baseVertexShader, ext.supportLinearFiltering ? advectionShader : advectionManualFilteringShader);
const divergenceProgram = new GLProgram(baseVertexShader, divergenceShader);
const curlProgram = new GLProgram(baseVertexShader, curlShader);
const vorticityProgram = new GLProgram(baseVertexShader, vorticityShader);
const pressureProgram = new GLProgram(baseVertexShader, pressureShader);
const gradienSubtractProgram = new GLProgram(baseVertexShader, gradientSubtractShader);
function initFramebuffers() {
  textureWidth = gl.drawingBufferWidth >> config.TEXTURE_DOWNSAMPLE;
  textureHeight = gl.drawingBufferHeight >> config.TEXTURE_DOWNSAMPLE;
  const texType = ext.halfFloatTexType;
  const rgba = ext.formatRGBA;
  const rg = ext.formatRG;
  const r = ext.formatR;
  density = createDoubleFBO(2, textureWidth, textureHeight, rgba.internalFormat, rgba.format, texType, ext.supportLinearFiltering ? gl.LINEAR : gl.NEAREST);
  velocity = createDoubleFBO(0, textureWidth, textureHeight, rg.internalFormat, rg.format, texType, ext.supportLinearFiltering ? gl.LINEAR : gl.NEAREST);
  divergence = createFBO(4, textureWidth, textureHeight, r.internalFormat, r.format, texType, gl.NEAREST);
  curl = createFBO(5, textureWidth, textureHeight, r.internalFormat, r.format, texType, gl.NEAREST);
  pressure = createDoubleFBO(6, textureWidth, textureHeight, r.internalFormat, r.format, texType, gl.NEAREST);
}
function createFBO(texId, w, h, internalFormat, format, type, param) {
  gl.activeTexture(gl.TEXTURE0 + texId);
  let texture = gl.createTexture();
  gl.bindTexture(gl.TEXTURE_2D, texture);
  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, param);
  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, param);
  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
  gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
  gl.texImage2D(gl.TEXTURE_2D, 0, internalFormat, w, h, 0, format, type, null);
  let fbo = gl.createFramebuffer();
  gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
  gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, 0);
  gl.viewport(0, 0, w, h);
  gl.clear(gl.COLOR_BUFFER_BIT);
  return [texture, fbo, texId];
}
function createDoubleFBO(texId, w, h, internalFormat, format, type, param) {
  let fbo1 = createFBO(texId, w, h, internalFormat, format, type, param);
  let fbo2 = createFBO(texId + 1, w, h, internalFormat, format, type, param);
  return {
    get read() {
      return fbo1;
    },
    get write() {
      return fbo2;
    },
    swap() {
      let temp = fbo1;
      fbo1 = fbo2;
      fbo2 = temp;
    } };
}
const blit = (() => {
  gl.bindBuffer(gl.ARRAY_BUFFER, gl.createBuffer());
  gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([-1, -1, -1, 1, 1, 1, 1, -1]), gl.STATIC_DRAW);
  gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, gl.createBuffer());
  gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array([0, 1, 2, 0, 2, 3]), gl.STATIC_DRAW);
  gl.vertexAttribPointer(0, 2, gl.FLOAT, false, 0, 0);
  gl.enableVertexAttribArray(0);
  return destination => {
    gl.bindFramebuffer(gl.FRAMEBUFFER, destination);
    gl.drawElements(gl.TRIANGLES, 6, gl.UNSIGNED_SHORT, 0);
  };
})();
let lastTime = Date.now();
multipleSplats(parseInt(Math.random() * 20) + 5);
update();
function update() {
  resizeCanvas();
  const dt = Math.min((Date.now() - lastTime) / 1000, 0.016);
  lastTime = Date.now();
  gl.viewport(0, 0, textureWidth, textureHeight);
  if (splatStack.length > 0)
  multipleSplats(splatStack.pop());
  advectionProgram.bind();
  gl.uniform2f(advectionProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight);
  gl.uniform1i(advectionProgram.uniforms.uVelocity, velocity.read[2]);
  gl.uniform1i(advectionProgram.uniforms.uSource, velocity.read[2]);
  gl.uniform1f(advectionProgram.uniforms.dt, dt);
  gl.uniform1f(advectionProgram.uniforms.dissipation, config.VELOCITY_DISSIPATION);
  blit(velocity.write[1]);
  velocity.swap();
  gl.uniform1i(advectionProgram.uniforms.uVelocity, velocity.read[2]);
  gl.uniform1i(advectionProgram.uniforms.uSource, density.read[2]);
  gl.uniform1f(advectionProgram.uniforms.dissipation, config.DENSITY_DISSIPATION);
  blit(density.write[1]);
  density.swap();
  for (let i = 0; i < pointers.length; i++) {
    const pointer = pointers[i];
    if (pointer.moved) {
      splat(pointer.x, pointer.y, pointer.dx, pointer.dy, pointer.color);
      pointer.moved = false;
    }
  }
  curlProgram.bind();
  gl.uniform2f(curlProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight);
  gl.uniform1i(curlProgram.uniforms.uVelocity, velocity.read[2]);
  blit(curl[1]);
  vorticityProgram.bind();
  gl.uniform2f(vorticityProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight);
  gl.uniform1i(vorticityProgram.uniforms.uVelocity, velocity.read[2]);
  gl.uniform1i(vorticityProgram.uniforms.uCurl, curl[2]);
  gl.uniform1f(vorticityProgram.uniforms.curl, config.CURL);
  gl.uniform1f(vorticityProgram.uniforms.dt, dt);
  blit(velocity.write[1]);
  velocity.swap();
  divergenceProgram.bind();
  gl.uniform2f(divergenceProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight);
  gl.uniform1i(divergenceProgram.uniforms.uVelocity, velocity.read[2]);
  blit(divergence[1]);
  clearProgram.bind();
  let pressureTexId = pressure.read[2];
  gl.activeTexture(gl.TEXTURE0 + pressureTexId);
  gl.bindTexture(gl.TEXTURE_2D, pressure.read[0]);
  gl.uniform1i(clearProgram.uniforms.uTexture, pressureTexId);
  gl.uniform1f(clearProgram.uniforms.value, config.PRESSURE_DISSIPATION);
  blit(pressure.write[1]);
  pressure.swap();
  pressureProgram.bind();
  gl.uniform2f(pressureProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight);
  gl.uniform1i(pressureProgram.uniforms.uDivergence, divergence[2]);
  pressureTexId = pressure.read[2];
  gl.uniform1i(pressureProgram.uniforms.uPressure, pressureTexId);
  gl.activeTexture(gl.TEXTURE0 + pressureTexId);
  for (let i = 0; i < config.PRESSURE_ITERATIONS; i++) {
    gl.bindTexture(gl.TEXTURE_2D, pressure.read[0]);
    blit(pressure.write[1]);
    pressure.swap();
  }
  gradienSubtractProgram.bind();
  gl.uniform2f(gradienSubtractProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight);
  gl.uniform1i(gradienSubtractProgram.uniforms.uPressure, pressure.read[2]);
  gl.uniform1i(gradienSubtractProgram.uniforms.uVelocity, velocity.read[2]);
  blit(velocity.write[1]);
  velocity.swap();
  gl.viewport(0, 0, gl.drawingBufferWidth, gl.drawingBufferHeight);
  displayProgram.bind();
  gl.uniform1i(displayProgram.uniforms.uTexture, density.read[2]);
  blit(null);
  requestAnimationFrame(update);
}
function splat(x, y, dx, dy, color) {
  splatProgram.bind();
  gl.uniform1i(splatProgram.uniforms.uTarget, velocity.read[2]);
  gl.uniform1f(splatProgram.uniforms.aspectRatio, canvas.width / canvas.height);
  gl.uniform2f(splatProgram.uniforms.point, x / canvas.width, 1.0 - y / canvas.height);
  gl.uniform3f(splatProgram.uniforms.color, dx, -dy, 1.0);
  gl.uniform1f(splatProgram.uniforms.radius, config.SPLAT_RADIUS);
  blit(velocity.write[1]);
  velocity.swap();
  gl.uniform1i(splatProgram.uniforms.uTarget, density.read[2]);
  gl.uniform3f(splatProgram.uniforms.color, color[0] * 0.3, color[1] * 0.3, color[2] * 0.3);
  blit(density.write[1]);
  density.swap();
}
function multipleSplats(amount) {
  for (let i = 0; i < amount; i++) {
    const color = [Math.random() * 10, Math.random() * 10, Math.random() * 10];
    const x = canvas.width * Math.random();
    const y = canvas.height * Math.random();
    const dx = 1000 * (Math.random() - 0.5);
    const dy = 1000 * (Math.random() - 0.5);
    splat(x, y, dx, dy, color);
  }
}
function resizeCanvas() {
  if (canvas.width != canvas.clientWidth || canvas.height != canvas.clientHeight) {
    canvas.width = canvas.clientWidth;
    canvas.height = canvas.clientHeight;
    initFramebuffers();
  }
}
canvas.addEventListener('mousemove', e => {
  pointers[0].moved = pointers[0].down;
  pointers[0].dx = (e.offsetX - pointers[0].x) * 10.0;
  pointers[0].dy = (e.offsetY - pointers[0].y) * 10.0;
  pointers[0].x = e.offsetX;
  pointers[0].y = e.offsetY;
});
canvas.addEventListener('touchmove', e => {
  e.preventDefault();
  const touches = e.targetTouches;
  for (let i = 0; i < touches.length; i++) {
    let pointer = pointers[i];
    pointer.moved = pointer.down;
    pointer.dx = (touches[i].pageX - pointer.x) * 10.0;
    pointer.dy = (touches[i].pageY - pointer.y) * 10.0;
    pointer.x = touches[i].pageX;
    pointer.y = touches[i].pageY;
  }
}, false);
canvas.addEventListener('mousemove', () => {
  pointers[0].down = true;
  pointers[0].color = [Math.random() + 0.2, Math.random() + 0.2, Math.random() + 0.2];
});
canvas.addEventListener('touchstart', e => {
  e.preventDefault();
  const touches = e.targetTouches;
  for (let i = 0; i < touches.length; i++) {
    if (i >= pointers.length)
    pointers.push(new pointerPrototype());
    pointers[i].id = touches[i].identifier;
    pointers[i].down = true;
    pointers[i].x = touches[i].pageX;
    pointers[i].y = touches[i].pageY;
    pointers[i].color = [Math.random() + 0.2, Math.random() + 0.2, Math.random() + 0.2];
  }
});
window.addEventListener('mouseleave', () => {
  pointers[0].down = false;
});
window.addEventListener('touchend', e => {
  const touches = e.changedTouches;
  for (let i = 0; i < touches.length; i++)
  for (let j = 0; j < pointers.length; j++)
  if (touches[i].identifier == pointers[j].id)
  pointers[j].down = false;
});
</script>

Tutup

JS dipetik dari codepen.io/DedaloD/pen/PoJGKOb