text: 'use strict';
  
  const canvas = document.getElementsByTagName('canvas')[0];
  canvas.width = canvas.clientWidth;
  canvas.height = canvas.clientHeight;
  
  let config = {
      SIM_RESOLUTION: 128,
      DYE_RESOLUTION: 512,
      DENSITY_DISSIPATION: 0.97,
      VELOCITY_DISSIPATION: 0.98,
      PRESSURE_DISSIPATION: 0.8,
      PRESSURE_ITERATIONS: 20,
      CURL: 30,
      SPLAT_RADIUS: 0.5,
      SHADING: true,
      COLORFUL: true,
      PAUSED: false,
      BACK_COLOR: { r: 0, g: 0, b: 0 },
      TRANSPARENT: false,
      BLOOM: true,
      BLOOM_ITERATIONS: 8,
      BLOOM_RESOLUTION: 256,
      BLOOM_INTENSITY: 0.8,
      BLOOM_THRESHOLD: 0.6,
      BLOOM_SOFT_KNEE: 0.7
  }
  
  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];
  }
  
  let pointers = [];
  let splatStack = [];
  let bloomFramebuffers = [];
  pointers.push(new pointerPrototype());
  
  const { gl, ext } = getWebGLContext(canvas);
  
  if (isMobile())
      config.SHADING = false;
  if (!ext.supportLinearFiltering)
  {
      config.SHADING = false;
      config.BLOOM = false;
  }
  
  startGUI();
  
  function getWebGLContext (canvas) {
      const params = { alpha: true, depth: false, stencil: false, antialias: false, preserveDrawingBuffer: 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);
      }
  
      if (formatRGBA == null)
          ga('send', 'event', isWebGL2 ? 'webgl2' : 'webgl', 'not supported');
      else
          ga('send', 'event', isWebGL2 ? 'webgl2' : 'webgl', 'supported');
  
      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 startGUI () {
      var gui = new dat.GUI({ width: 300 });
      gui.add(config, 'SIM_RESOLUTION', { '32': 32, '64': 64, '128': 128, '256': 256 }).name('sim resolution').onFinishChange(initFramebuffers);
      gui.add(config, 'DYE_RESOLUTION', { '128': 128, '256': 256, '512': 512, '1024': 1024 }).name('dye resolution').onFinishChange(initFramebuffers);
      gui.add(config, 'DENSITY_DISSIPATION', 0.9, 1.0).name('density diffusion');
      gui.add(config, 'VELOCITY_DISSIPATION', 0.9, 1.0).name('velocity diffusion');
      gui.add(config, 'PRESSURE_DISSIPATION', 0.0, 1.0).name('pressure diffusion');
      gui.add(config, 'CURL', 0, 50).name('vorticity').step(1);
      gui.add(config, 'SPLAT_RADIUS', 0.01, 1.0).name('splat radius');
      gui.add(config, 'SHADING').name('shading');
      gui.add(config, 'COLORFUL').name('colorful');
      gui.add(config, 'PAUSED').name('paused').listen();
  
      gui.add({ fun: () => {
          splatStack.push(parseInt(Math.random() * 20) + 5);
      } }, 'fun').name('Random splats');
  
      let bloomFolder = gui.addFolder('Bloom');
      bloomFolder.add(config, 'BLOOM').name('enabled');
      bloomFolder.add(config, 'BLOOM_INTENSITY', 0.1, 2.0).name('intensity');
      bloomFolder.add(config, 'BLOOM_THRESHOLD', 0.0, 1.0).name('threshold');
  
      let captureFolder = gui.addFolder('Capture');
      captureFolder.addColor(config, 'BACK_COLOR').name('background color');
      captureFolder.add(config, 'TRANSPARENT').name('transparent');
      captureFolder.add({ fun: captureScreenshot }, 'fun').name('take screenshot');
  
      let github = gui.add({ fun : () => {
          window.open('https://github.com/PavelDoGreat/WebGL-Fluid-Simulation');
          ga('send', 'event', 'link button', 'github');
      } }, 'fun').name('Github');
      github.__li.className = 'cr function bigFont';
      github.__li.style.borderLeft = '3px solid #8C8C8C';
      let githubIcon = document.createElement('span');
      github.domElement.parentElement.appendChild(githubIcon);
      githubIcon.className = 'icon github';
  
      let twitter = gui.add({ fun : () => {
          ga('send', 'event', 'link button', 'twitter');
          window.open('https://twitter.com/PavelDoGreat');
      } }, 'fun').name('Twitter');
      twitter.__li.className = 'cr function bigFont';
      twitter.__li.style.borderLeft = '3px solid #8C8C8C';
      let twitterIcon = document.createElement('span');
      twitter.domElement.parentElement.appendChild(twitterIcon);
      twitterIcon.className = 'icon twitter';
  
      let discord = gui.add({ fun : () => {
          ga('send', 'event', 'link button', 'discord');
          window.open('https://discordapp.com/invite/CeqZDDE');
      } }, 'fun').name('Discord');
      discord.__li.className = 'cr function bigFont';
      discord.__li.style.borderLeft = '3px solid #8C8C8C';
      let discordIcon = document.createElement('span');
      discord.domElement.parentElement.appendChild(discordIcon);
      discordIcon.className = 'icon discord';
  
      let app = gui.add({ fun : () => {
          ga('send', 'event', 'link button', 'app');
          window.open('http://onelink.to/5b58bn');
      } }, 'fun').name('Check out new improved version');
      app.__li.className = 'cr function appBigFont';
      app.__li.style.borderLeft = '3px solid #00FF7F';
      let appIcon = document.createElement('span');
      app.domElement.parentElement.appendChild(appIcon);
      appIcon.className = 'icon app';
  
      if (isMobile())
          gui.close();
  }
  
  function captureScreenshot () {
      colorProgram.bind();
      gl.uniform4f(colorProgram.uniforms.color, 0, 0, 0, 1);
      blit(density.write.fbo);
  
      render(density.write.fbo);
      gl.bindFramebuffer(gl.FRAMEBUFFER, density.write.fbo);
  
      let length = dyeWidth * dyeHeight * 4;
      let pixels = new Float32Array(length);
      gl.readPixels(0, 0, dyeWidth, dyeHeight, gl.RGBA, gl.FLOAT, pixels);
  
      let newPixels = new Uint8Array(length);
  
      let id = 0;
      for (let i = dyeHeight - 1; i >= 0; i--) {
          for (let j = 0; j < dyeWidth; j++) {
              let nid = i * dyeWidth * 4 + j * 4;
              newPixels[nid + 0] = clamp01(pixels[id + 0]) * 255;
              newPixels[nid + 1] = clamp01(pixels[id + 1]) * 255;
              newPixels[nid + 2] = clamp01(pixels[id + 2]) * 255;
              newPixels[nid + 3] = clamp01(pixels[id + 3]) * 255;
              id += 4;
          }
      }
  
      let captureCanvas = document.createElement('canvas');
      let ctx = captureCanvas.getContext('2d');
      captureCanvas.width = dyeWidth;
      captureCanvas.height = dyeHeight;
  
      let imageData = ctx.createImageData(dyeWidth, dyeHeight);
      imageData.data.set(newPixels);
      ctx.putImageData(imageData, 0, 0);
      let datauri = captureCanvas.toDataURL();
  
      downloadURI("fluid.png", datauri);
  
      URL.revokeObjectURL(datauri);
  }
  
  function clamp01 (input) {
      return Math.min(Math.max(input, 0), 1);
  }
  
  function downloadURI (filename, uri) {
      let link = document.createElement("a");
      link.download = filename;
      link.href = uri;
      document.body.appendChild(link);
      link.click();
      document.body.removeChild(link);
  }
  
  function isMobile () {
      return /Mobi|Android/i.test(navigator.userAgent);
  }
  
  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;
  
      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 mediump float;
      precision mediump sampler2D;
  
      varying highp vec2 vUv;
      uniform sampler2D uTexture;
      uniform float value;
  
      void main () {
          gl_FragColor = value * texture2D(uTexture, vUv);
      }
  `);
  
  const colorShader = compileShader(gl.FRAGMENT_SHADER, `
      precision mediump float;
  
      uniform vec4 color;
  
      void main () {
          gl_FragColor = color;
      }
  `);
  
  const backgroundShader = compileShader(gl.FRAGMENT_SHADER, `
      precision highp float;
      precision highp sampler2D;
  
      varying vec2 vUv;
      uniform sampler2D uTexture;
      uniform float aspectRatio;
  
      #define SCALE 25.0
  
      void main () {
          vec2 uv = floor(vUv * SCALE * vec2(aspectRatio, 1.0));
          float v = mod(uv.x + uv.y, 2.0);
          v = v * 0.1 + 0.8;
          gl_FragColor = vec4(vec3(v), 1.0);
      }
  `);
  
  const displayShader = compileShader(gl.FRAGMENT_SHADER, `
      precision highp float;
      precision highp sampler2D;
  
      varying vec2 vUv;
      uniform sampler2D uTexture;
  
      void main () {
          vec3 C = texture2D(uTexture, vUv).rgb;
          float a = max(C.r, max(C.g, C.b));
          gl_FragColor = vec4(C, a);
      }
  `);
  
  const displayBloomShader = compileShader(gl.FRAGMENT_SHADER, `
      precision highp float;
      precision highp sampler2D;
  
      varying vec2 vUv;
      uniform sampler2D uTexture;
      uniform sampler2D uBloom;
      uniform sampler2D uDithering;
      uniform vec2 ditherScale;
  
      void main () {
          vec3 C = texture2D(uTexture, vUv).rgb;
          vec3 bloom = texture2D(uBloom, vUv).rgb;
          vec3 noise = texture2D(uDithering, vUv * ditherScale).rgb;
          noise = noise * 2.0 - 1.0;
          bloom += noise / 800.0;
          bloom = pow(bloom.rgb, vec3(1.0 / 2.2));
          C += bloom;
          float a = max(C.r, max(C.g, C.b));
          gl_FragColor = vec4(C, a);
      }
  `);
  
  const displayShadingShader = compileShader(gl.FRAGMENT_SHADER, `
      precision highp float;
      precision highp sampler2D;
  
      varying vec2 vUv;
      varying vec2 vL;
      varying vec2 vR;
      varying vec2 vT;
      varying vec2 vB;
      uniform sampler2D uTexture;
      uniform vec2 texelSize;
  
      void main () {
          vec3 L = texture2D(uTexture, vL).rgb;
          vec3 R = texture2D(uTexture, vR).rgb;
          vec3 T = texture2D(uTexture, vT).rgb;
          vec3 B = texture2D(uTexture, vB).rgb;
          vec3 C = texture2D(uTexture, vUv).rgb;
  
          float dx = length(R) - length(L);
          float dy = length(T) - length(B);
  
          vec3 n = normalize(vec3(dx, dy, length(texelSize)));
          vec3 l = vec3(0.0, 0.0, 1.0);
  
          float diffuse = clamp(dot(n, l) + 0.7, 0.7, 1.0);
          C.rgb *= diffuse;
  
          float a = max(C.r, max(C.g, C.b));
          gl_FragColor = vec4(C, a);
      }
  `);
  
  const displayBloomShadingShader = compileShader(gl.FRAGMENT_SHADER, `
      precision highp float;
      precision highp sampler2D;
  
      varying vec2 vUv;
      varying vec2 vL;
      varying vec2 vR;
      varying vec2 vT;
      varying vec2 vB;
      uniform sampler2D uTexture;
      uniform sampler2D uBloom;
      uniform sampler2D uDithering;
      uniform vec2 ditherScale;
      uniform vec2 texelSize;
  
      void main () {
          vec3 L = texture2D(uTexture, vL).rgb;
          vec3 R = texture2D(uTexture, vR).rgb;
          vec3 T = texture2D(uTexture, vT).rgb;
          vec3 B = texture2D(uTexture, vB).rgb;
          vec3 C = texture2D(uTexture, vUv).rgb;
  
          float dx = length(R) - length(L);
          float dy = length(T) - length(B);
  
          vec3 n = normalize(vec3(dx, dy, length(texelSize)));
          vec3 l = vec3(0.0, 0.0, 1.0);
  
          float diffuse = clamp(dot(n, l) + 0.7, 0.7, 1.0);
          C *= diffuse;
  
          vec3 bloom = texture2D(uBloom, vUv).rgb;
          vec3 noise = texture2D(uDithering, vUv * ditherScale).rgb;
          noise = noise * 2.0 - 1.0;
          bloom += noise / 800.0;
          bloom = pow(bloom.rgb, vec3(1.0 / 2.2));
          C += bloom;
  
          float a = max(C.r, max(C.g, C.b));
          gl_FragColor = vec4(C, a);
      }
  `);
  
  const bloomPrefilterShader = compileShader(gl.FRAGMENT_SHADER, `
      precision mediump float;
      precision mediump sampler2D;
  
      varying vec2 vUv;
      uniform sampler2D uTexture;
      uniform vec3 curve;
      uniform float threshold;
  
      void main () {
          vec3 c = texture2D(uTexture, vUv).rgb;
          float br = max(c.r, max(c.g, c.b));
          float rq = clamp(br - curve.x, 0.0, curve.y);
          rq = curve.z * rq * rq;
          c *= max(rq, br - threshold) / max(br, 0.0001);
          gl_FragColor = vec4(c, 0.0);
      }
  `);
  
  const bloomBlurShader = compileShader(gl.FRAGMENT_SHADER, `
      precision mediump float;
      precision mediump sampler2D;
  
      varying vec2 vL;
      varying vec2 vR;
      varying vec2 vT;
      varying vec2 vB;
      uniform sampler2D uTexture;
  
      void main () {
          vec4 sum = vec4(0.0);
          sum += texture2D(uTexture, vL);
          sum += texture2D(uTexture, vR);
          sum += texture2D(uTexture, vT);
          sum += texture2D(uTexture, vB);
          sum *= 0.25;
          gl_FragColor = sum;
      }
  `);
  
  const bloomFinalShader = compileShader(gl.FRAGMENT_SHADER, `
      precision mediump float;
      precision mediump sampler2D;
  
      varying vec2 vL;
      varying vec2 vR;
      varying vec2 vT;
      varying vec2 vB;
      uniform sampler2D uTexture;
      uniform float intensity;
  
      void main () {
          vec4 sum = vec4(0.0);
          sum += texture2D(uTexture, vL);
          sum += texture2D(uTexture, vR);
          sum += texture2D(uTexture, vT);
          sum += texture2D(uTexture, vB);
          sum *= 0.25;
          gl_FragColor = sum * intensity;
      }
  `);
  
  const splatShader = compileShader(gl.FRAGMENT_SHADER, `
      precision highp float;
      precision highp 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 highp sampler2D;
  
      varying vec2 vUv;
      uniform sampler2D uVelocity;
      uniform sampler2D uSource;
      uniform vec2 texelSize;
      uniform vec2 dyeTexelSize;
      uniform float dt;
      uniform float dissipation;
  
      vec4 bilerp (sampler2D sam, vec2 uv, vec2 tsize) {
          vec2 st = uv / tsize - 0.5;
  
          vec2 iuv = floor(st);
          vec2 fuv = fract(st);
  
          vec4 a = texture2D(sam, (iuv + vec2(0.5, 0.5)) * tsize);
          vec4 b = texture2D(sam, (iuv + vec2(1.5, 0.5)) * tsize);
          vec4 c = texture2D(sam, (iuv + vec2(0.5, 1.5)) * tsize);
          vec4 d = texture2D(sam, (iuv + vec2(1.5, 1.5)) * tsize);
  
          return mix(mix(a, b, fuv.x), mix(c, d, fuv.x), fuv.y);
      }
  
      void main () {
          vec2 coord = vUv - dt * bilerp(uVelocity, vUv, texelSize).xy * texelSize;
          gl_FragColor = dissipation * bilerp(uSource, coord, dyeTexelSize);
          gl_FragColor.a = 1.0;
      }
  `);
  
  const advectionShader = compileShader(gl.FRAGMENT_SHADER, `
      precision highp float;
      precision highp 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 mediump float;
      precision mediump sampler2D;
  
      varying highp vec2 vUv;
      varying highp vec2 vL;
      varying highp vec2 vR;
      varying highp vec2 vT;
      varying highp vec2 vB;
      uniform sampler2D uVelocity;
  
      void main () {
          float L = texture2D(uVelocity, vL).x;
          float R = texture2D(uVelocity, vR).x;
          float T = texture2D(uVelocity, vT).y;
          float B = texture2D(uVelocity, vB).y;
  
          vec2 C = texture2D(uVelocity, vUv).xy;
          if (vL.x < 0.0) { L = -C.x; }
          if (vR.x > 1.0) { R = -C.x; }
          if (vT.y > 1.0) { T = -C.y; }
          if (vB.y < 0.0) { B = -C.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 mediump float;
      precision mediump sampler2D;
  
      varying highp vec2 vUv;
      varying highp vec2 vL;
      varying highp vec2 vR;
      varying highp vec2 vT;
      varying highp 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(0.5 * vorticity, 0.0, 0.0, 1.0);
      }
  `);
  
  const vorticityShader = compileShader(gl.FRAGMENT_SHADER, `
      precision highp float;
      precision highp sampler2D;
  
      varying vec2 vUv;
      varying vec2 vL;
      varying vec2 vR;
      varying vec2 vT;
      varying vec2 vB;
      uniform sampler2D uVelocity;
      uniform sampler2D uCurl;
      uniform float curl;
      uniform float dt;
  
      void main () {
          float L = texture2D(uCurl, vL).x;
          float R = texture2D(uCurl, vR).x;
          float T = texture2D(uCurl, vT).x;
          float B = texture2D(uCurl, vB).x;
          float C = texture2D(uCurl, vUv).x;
  
          vec2 force = 0.5 * vec2(abs(T) - abs(B), abs(R) - abs(L));
          force /= length(force) + 0.0001;
          force *= curl * C;
          force.y *= -1.0;
  
          vec2 vel = texture2D(uVelocity, vUv).xy;
          gl_FragColor = vec4(vel + force * dt, 0.0, 1.0);
      }
  `);
  
  const pressureShader = compileShader(gl.FRAGMENT_SHADER, `
      precision mediump float;
      precision mediump sampler2D;
  
      varying highp vec2 vUv;
      varying highp vec2 vL;
      varying highp vec2 vR;
      varying highp vec2 vT;
      varying highp vec2 vB;
      uniform sampler2D uPressure;
      uniform sampler2D uDivergence;
  
      vec2 boundary (vec2 uv) {
          return uv;
          // uncomment if you use wrap or repeat texture mode
          // 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 mediump float;
      precision mediump sampler2D;
  
      varying highp vec2 vUv;
      varying highp vec2 vL;
      varying highp vec2 vR;
      varying highp vec2 vT;
      varying highp vec2 vB;
      uniform sampler2D uPressure;
      uniform sampler2D uVelocity;
  
      vec2 boundary (vec2 uv) {
          return 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);
      }
  `);
  
  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 simWidth;
  let simHeight;
  let dyeWidth;
  let dyeHeight;
  let density;
  let velocity;
  let divergence;
  let curl;
  let pressure;
  let bloom;
  
  let ditheringTexture = createTextureAsync('LDR_RGB1_0.png');
  
  const clearProgram               = new GLProgram(baseVertexShader, clearShader);
  const colorProgram               = new GLProgram(baseVertexShader, colorShader);
  const backgroundProgram          = new GLProgram(baseVertexShader, backgroundShader);
  const displayProgram             = new GLProgram(baseVertexShader, displayShader);
  const displayBloomProgram        = new GLProgram(baseVertexShader, displayBloomShader);
  const displayShadingProgram      = new GLProgram(baseVertexShader, displayShadingShader);
  const displayBloomShadingProgram = new GLProgram(baseVertexShader, displayBloomShadingShader);
  const bloomPrefilterProgram      = new GLProgram(baseVertexShader, bloomPrefilterShader);
  const bloomBlurProgram           = new GLProgram(baseVertexShader, bloomBlurShader);
  const bloomFinalProgram          = new GLProgram(baseVertexShader, bloomFinalShader);
  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 () {
      let simRes = getResolution(config.SIM_RESOLUTION);
      let dyeRes = getResolution(config.DYE_RESOLUTION);
  
      simWidth  = simRes.width;
      simHeight = simRes.height;
      dyeWidth  = dyeRes.width;
      dyeHeight = dyeRes.height;
  
      const texType = ext.halfFloatTexType;
      const rgba    = ext.formatRGBA;
      const rg      = ext.formatRG;
      const r       = ext.formatR;
      const filtering = ext.supportLinearFiltering ? gl.LINEAR : gl.NEAREST;
  
      if (density == null)
          density = createDoubleFBO(dyeWidth, dyeHeight, rgba.internalFormat, rgba.format, texType, filtering);
      else
          density = resizeDoubleFBO(density, dyeWidth, dyeHeight, rgba.internalFormat, rgba.format, texType, filtering);
  
      if (velocity == null)
          velocity = createDoubleFBO(simWidth, simHeight, rg.internalFormat, rg.format, texType, filtering);
      else
          velocity = resizeDoubleFBO(velocity, simWidth, simHeight, rg.internalFormat, rg.format, texType, filtering);
  
      divergence = createFBO      (simWidth, simHeight, r.internalFormat, r.format, texType, gl.NEAREST);
      curl       = createFBO      (simWidth, simHeight, r.internalFormat, r.format, texType, gl.NEAREST);
      pressure   = createDoubleFBO(simWidth, simHeight, r.internalFormat, r.format, texType, gl.NEAREST);
  
      initBloomFramebuffers();
  }
  
  function initBloomFramebuffers () {
      let res = getResolution(config.BLOOM_RESOLUTION);
  
      const texType = ext.halfFloatTexType;
      const rgba = ext.formatRGBA;
      const filtering = ext.supportLinearFiltering ? gl.LINEAR : gl.NEAREST;
  
      bloom = createFBO(res.width, res.height, rgba.internalFormat, rgba.format, texType, filtering);
  
      bloomFramebuffers.length = 0;
      for (let i = 0; i < config.BLOOM_ITERATIONS; i++)
      {
          let width = res.width >> (i + 1);
          let height = res.height >> (i + 1);
  
          if (width < 2 || height < 2) break;
  
          let fbo = createFBO(width, height, rgba.internalFormat, rgba.format, texType, filtering);
          bloomFramebuffers.push(fbo);
      }
  }
  
  function createFBO (w, h, internalFormat, format, type, param) {
      gl.activeTexture(gl.TEXTURE0);
      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,
          width: w,
          height: h,
          attach (id) {
              gl.activeTexture(gl.TEXTURE0 + id);
              gl.bindTexture(gl.TEXTURE_2D, texture);
              return id;
          }
      };
  }
  
  function createDoubleFBO (w, h, internalFormat, format, type, param) {
      let fbo1 = createFBO(w, h, internalFormat, format, type, param);
      let fbo2 = createFBO(w, h, internalFormat, format, type, param);
  
      return {
          get read () {
              return fbo1;
          },
          set read (value) {
              fbo1 = value;
          },
          get write () {
              return fbo2;
          },
          set write (value) {
              fbo2 = value;
          },
          swap () {
              let temp = fbo1;
              fbo1 = fbo2;
              fbo2 = temp;
          }
      }
  }
  
  function resizeFBO (target, w, h, internalFormat, format, type, param) {
      let newFBO = createFBO(w, h, internalFormat, format, type, param);
      clearProgram.bind();
      gl.uniform1i(clearProgram.uniforms.uTexture, target.attach(0));
      gl.uniform1f(clearProgram.uniforms.value, 1);
      blit(newFBO.fbo);
      return newFBO;
  }
  
  function resizeDoubleFBO (target, w, h, internalFormat, format, type, param) {
      target.read = resizeFBO(target.read, w, h, internalFormat, format, type, param);
      target.write = createFBO(w, h, internalFormat, format, type, param);
      return target;
  }
  
  function createTextureAsync (url) {
      let texture = gl.createTexture();
      gl.bindTexture(gl.TEXTURE_2D, texture);
      gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
      gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
      gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.REPEAT);
      gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.REPEAT);
      gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGB, 1, 1, 0, gl.RGB, gl.UNSIGNED_BYTE, new Uint8Array([255, 255, 255]));
  
      let obj = {
          texture,
          width: 1,
          height: 1,
          attach (id) {
              gl.activeTexture(gl.TEXTURE0 + id);
              gl.bindTexture(gl.TEXTURE_2D, texture);
              return id;
          }
      };
  
      let image = new Image();
      image.onload = () => {
          obj.width = image.width;
          obj.height = image.height;
          gl.bindTexture(gl.TEXTURE_2D, texture);
          gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGB, gl.RGB, gl.UNSIGNED_BYTE, image);
      };
      image.src = url;
  
      return obj;
  }
  
  initFramebuffers();
  multipleSplats(parseInt(Math.random() * 20) + 5);
  
  let lastColorChangeTime = Date.now();
  
  update();
  
  function update () {
      resizeCanvas();
      input();
      if (!config.PAUSED)
          step(0.016);
      render(null);
      requestAnimationFrame(update);
  }
  
  function input () {
      if (splatStack.length > 0)
          multipleSplats(splatStack.pop());
  
      for (let i = 0; i < pointers.length; i++) {
          const p = pointers[i];
          if (p.moved) {
              splat(p.x, p.y, p.dx, p.dy, p.color);
              p.moved = false;
          }
      }
  
      if (!config.COLORFUL)
          return;
  
      if (lastColorChangeTime + 100 < Date.now())
      {
          lastColorChangeTime = Date.now();
          for (let i = 0; i < pointers.length; i++) {
              const p = pointers[i];
              p.color = generateColor();
          }
      }
  }
  
  function step (dt) {
      gl.disable(gl.BLEND);
      gl.viewport(0, 0, simWidth, simHeight);
  
      curlProgram.bind();
      gl.uniform2f(curlProgram.uniforms.texelSize, 1.0 / simWidth, 1.0 / simHeight);
      gl.uniform1i(curlProgram.uniforms.uVelocity, velocity.read.attach(0));
      blit(curl.fbo);
  
      vorticityProgram.bind();
      gl.uniform2f(vorticityProgram.uniforms.texelSize, 1.0 / simWidth, 1.0 / simHeight);
      gl.uniform1i(vorticityProgram.uniforms.uVelocity, velocity.read.attach(0));
      gl.uniform1i(vorticityProgram.uniforms.uCurl, curl.attach(1));
      gl.uniform1f(vorticityProgram.uniforms.curl, config.CURL);
      gl.uniform1f(vorticityProgram.uniforms.dt, dt);
      blit(velocity.write.fbo);
      velocity.swap();
  
      divergenceProgram.bind();
      gl.uniform2f(divergenceProgram.uniforms.texelSize, 1.0 / simWidth, 1.0 / simHeight);
      gl.uniform1i(divergenceProgram.uniforms.uVelocity, velocity.read.attach(0));
      blit(divergence.fbo);
  
      clearProgram.bind();
      gl.uniform1i(clearProgram.uniforms.uTexture, pressure.read.attach(0));
      gl.uniform1f(clearProgram.uniforms.value, config.PRESSURE_DISSIPATION);
      blit(pressure.write.fbo);
      pressure.swap();
  
      pressureProgram.bind();
      gl.uniform2f(pressureProgram.uniforms.texelSize, 1.0 / simWidth, 1.0 / simHeight);
      gl.uniform1i(pressureProgram.uniforms.uDivergence, divergence.attach(0));
      for (let i = 0; i < config.PRESSURE_ITERATIONS; i++) {
          gl.uniform1i(pressureProgram.uniforms.uPressure, pressure.read.attach(1));
          blit(pressure.write.fbo);
          pressure.swap();
      }
  
      gradienSubtractProgram.bind();
      gl.uniform2f(gradienSubtractProgram.uniforms.texelSize, 1.0 / simWidth, 1.0 / simHeight);
      gl.uniform1i(gradienSubtractProgram.uniforms.uPressure, pressure.read.attach(0));
      gl.uniform1i(gradienSubtractProgram.uniforms.uVelocity, velocity.read.attach(1));
      blit(velocity.write.fbo);
      velocity.swap();
  
      advectionProgram.bind();
      gl.uniform2f(advectionProgram.uniforms.texelSize, 1.0 / simWidth, 1.0 / simHeight);
      if (!ext.supportLinearFiltering)
          gl.uniform2f(advectionProgram.uniforms.dyeTexelSize, 1.0 / simWidth, 1.0 / simHeight);
      let velocityId = velocity.read.attach(0);
      gl.uniform1i(advectionProgram.uniforms.uVelocity, velocityId);
      gl.uniform1i(advectionProgram.uniforms.uSource, velocityId);
      gl.uniform1f(advectionProgram.uniforms.dt, dt);
      gl.uniform1f(advectionProgram.uniforms.dissipation, config.VELOCITY_DISSIPATION);
      blit(velocity.write.fbo);
      velocity.swap();
  
      gl.viewport(0, 0, dyeWidth, dyeHeight);
  
      if (!ext.supportLinearFiltering)
          gl.uniform2f(advectionProgram.uniforms.dyeTexelSize, 1.0 / dyeWidth, 1.0 / dyeHeight);
      gl.uniform1i(advectionProgram.uniforms.uVelocity, velocity.read.attach(0));
      gl.uniform1i(advectionProgram.uniforms.uSource, density.read.attach(1));
      gl.uniform1f(advectionProgram.uniforms.dissipation, config.DENSITY_DISSIPATION);
      blit(density.write.fbo);
      density.swap();
  }
  
  function render (target) {
      if (config.BLOOM)
          applyBloom(density.read, bloom);
  
      if (target == null || !config.TRANSPARENT) {
          gl.blendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
          gl.enable(gl.BLEND);
      }
      else {
          gl.disable(gl.BLEND);
      }
  
      let width  = target == null ? gl.drawingBufferWidth : dyeWidth;
      let height = target == null ? gl.drawingBufferHeight : dyeHeight;
  
      gl.viewport(0, 0, width, height);
  
      if (!config.TRANSPARENT) {
          colorProgram.bind();
          let bc = config.BACK_COLOR;
          gl.uniform4f(colorProgram.uniforms.color, bc.r / 255, bc.g / 255, bc.b / 255, 1);
          blit(target);
      }
  
      if (target == null && config.TRANSPARENT) {
          backgroundProgram.bind();
          gl.uniform1f(backgroundProgram.uniforms.aspectRatio, canvas.width / canvas.height);
          blit(null);
      }
  
      if (config.SHADING) {
          let program = config.BLOOM ? displayBloomShadingProgram : displayShadingProgram;
          program.bind();
          gl.uniform2f(program.uniforms.texelSize, 1.0 / width, 1.0 / height);
          gl.uniform1i(program.uniforms.uTexture, density.read.attach(0));
          if (config.BLOOM) {
              gl.uniform1i(program.uniforms.uBloom, bloom.attach(1));
              gl.uniform1i(program.uniforms.uDithering, ditheringTexture.attach(2));
              let scale = getTextureScale(ditheringTexture, width, height);
              gl.uniform2f(program.uniforms.ditherScale, scale.x, scale.y);
          }
      }
      else {
          let program = config.BLOOM ? displayBloomProgram : displayProgram;
          program.bind();
          gl.uniform1i(program.uniforms.uTexture, density.read.attach(0));
          if (config.BLOOM) {
              gl.uniform1i(program.uniforms.uBloom, bloom.attach(1));
              gl.uniform1i(program.uniforms.uDithering, ditheringTexture.attach(2));
              let scale = getTextureScale(ditheringTexture, width, height);
              gl.uniform2f(program.uniforms.ditherScale, scale.x, scale.y);
          }
      }
  
      blit(target);
  }
  
  function applyBloom (source, destination) {
      if (bloomFramebuffers.length < 2)
          return;
  
      let last = destination;
  
      gl.disable(gl.BLEND);
      bloomPrefilterProgram.bind();
      let knee = config.BLOOM_THRESHOLD * config.BLOOM_SOFT_KNEE + 0.0001;
      let curve0 = config.BLOOM_THRESHOLD - knee;
      let curve1 = knee * 2;
      let curve2 = 0.25 / knee;
      gl.uniform3f(bloomPrefilterProgram.uniforms.curve, curve0, curve1, curve2);
      gl.uniform1f(bloomPrefilterProgram.uniforms.threshold, config.BLOOM_THRESHOLD);
      gl.uniform1i(bloomPrefilterProgram.uniforms.uTexture, source.attach(0));
      gl.viewport(0, 0, last.width, last.height);
      blit(last.fbo);
  
      bloomBlurProgram.bind();
      for (let i = 0; i < bloomFramebuffers.length; i++) {
          let dest = bloomFramebuffers[i];
          gl.uniform2f(bloomBlurProgram.uniforms.texelSize, 1.0 / last.width, 1.0 / last.height);
          gl.uniform1i(bloomBlurProgram.uniforms.uTexture, last.attach(0));
          gl.viewport(0, 0, dest.width, dest.height);
          blit(dest.fbo);
          last = dest;
      }
  
      gl.blendFunc(gl.ONE, gl.ONE);
      gl.enable(gl.BLEND);
  
      for (let i = bloomFramebuffers.length - 2; i >= 0; i--) {
          let baseTex = bloomFramebuffers[i];
          gl.uniform2f(bloomBlurProgram.uniforms.texelSize, 1.0 / last.width, 1.0 / last.height);
          gl.uniform1i(bloomBlurProgram.uniforms.uTexture, last.attach(0));
          gl.viewport(0, 0, baseTex.width, baseTex.height);
          blit(baseTex.fbo);
          last = baseTex;
      }
  
      gl.disable(gl.BLEND);
      bloomFinalProgram.bind();
      gl.uniform2f(bloomFinalProgram.uniforms.texelSize, 1.0 / last.width, 1.0 / last.height);
      gl.uniform1i(bloomFinalProgram.uniforms.uTexture, last.attach(0));
      gl.uniform1f(bloomFinalProgram.uniforms.intensity, config.BLOOM_INTENSITY);
      gl.viewport(0, 0, destination.width, destination.height);
      blit(destination.fbo);
  }
  
  function splat (x, y, dx, dy, color) {
      gl.viewport(0, 0, simWidth, simHeight);
      splatProgram.bind();
      gl.uniform1i(splatProgram.uniforms.uTarget, velocity.read.attach(0));
      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 / 100.0);
      blit(velocity.write.fbo);
      velocity.swap();
  
      gl.viewport(0, 0, dyeWidth, dyeHeight);
      gl.uniform1i(splatProgram.uniforms.uTarget, density.read.attach(0));
      gl.uniform3f(splatProgram.uniforms.color, color.r, color.g, color.b);
      blit(density.write.fbo);
      density.swap();
  }
  
  function multipleSplats (amount) {
      for (let i = 0; i < amount; i++) {
          const color = generateColor();
          color.r *= 10.0;
          color.g *= 10.0;
          color.b *= 10.0;
          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) * 5.0;
      pointers[0].dy = (e.offsetY - pointers[0].y) * 5.0;
      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) * 8.0;
          pointer.dy = (touches[i].pageY - pointer.y) * 8.0;
          pointer.x = touches[i].pageX;
          pointer.y = touches[i].pageY;
      }
  }, false);
  
  canvas.addEventListener('mousedown', () => {
      pointers[0].down = true;
      pointers[0].color = generateColor();
  });
  
  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 = generateColor();
      }
  });
  
  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;
  });
  
  window.addEventListener('keydown', e => {
      if (e.code === 'KeyP')
          config.PAUSED = !config.PAUSED;
      if (e.key === ' ')
          splatStack.push(parseInt(Math.random() * 20) + 5);
  });
  
  function generateColor () {
      let c = HSVtoRGB(Math.random(), 1.0, 1.0);
      c.r *= 0.15;
      c.g *= 0.15;
      c.b *= 0.15;
      return c;
  }
  
  function HSVtoRGB (h, s, v) {
      let r, g, b, i, f, p, q, t;
      i = Math.floor(h * 6);
      f = h * 6 - i;
      p = v * (1 - s);
      q = v * (1 - f * s);
      t = v * (1 - (1 - f) * s);
  
      switch (i % 6) {
          case 0: r = v, g = t, b = p; break;
          case 1: r = q, g = v, b = p; break;
          case 2: r = p, g = v, b = t; break;
          case 3: r = p, g = q, b = v; break;
          case 4: r = t, g = p, b = v; break;
          case 5: r = v, g = p, b = q; break;
      }
  
      return {
          r,
          g,
          b
      };
  }
  
  function getResolution (resolution) {
      let aspectRatio = gl.drawingBufferWidth / gl.drawingBufferHeight;
      if (aspectRatio < 1)
          aspectRatio = 1.0 / aspectRatio;
  
      let max = Math.round(resolution * aspectRatio);
      let min = Math.round(resolution);
  
      if (gl.drawingBufferWidth > gl.drawingBufferHeight)
          return { width: max, height: min };
      else
          return { width: min, height: max };
  }
  
  function getTextureScale (texture, width, height) {
      return {
          x: width / texture.width,
          y: height / texture.height
      };
  }