WebGL сильно грузит процессор. Проект на django, подключаю файл js в html 5 на страницу и компьютер начинает разрываться

Question

'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: 30,
  SPLAT_RADIUS: 0.005
}
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('mousedown', () => {
  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('mouseup', () => {
  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;
});

<canvas></canvas>