← Mike Higgins Home
Custom Code Experiment •

Fluid Background

Source Code View HTML / CSS / JavaScript
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Fluid Background</title>
    <style>
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            background: #000;
            overflow: hidden;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }

        #container {
            position: relative;
            width: 100vw;
            height: 100vh;
        }

        canvas {
            display: block;
            width: 100%;
            height: 100%;
            cursor: crosshair;
        }

        #controls {
            position: fixed;
            bottom: 20px;
            left: 50%;
            transform: translateX(-50%);
            background: rgba(0, 0, 0, 0.7);
            color: white;
            padding: 10px 20px;
            border-radius: 20px;
            display: flex;
            gap: 15px;
            align-items: center;
            z-index: 100;
            backdrop-filter: blur(10px);
            border: 1px solid rgba(255, 255, 255, 0.1);
        }

        .control-btn {
            background: rgba(255, 255, 255, 0.1);
            border: none;
            color: white;
            padding: 8px 15px;
            border-radius: 15px;
            cursor: pointer;
            transition: all 0.3s ease;
            font-size: 14px;
        }

        .control-btn:hover {
            background: rgba(255, 255, 255, 0.2);
            transform: translateY(-2px);
        }

        .control-btn:active {
            transform: translateY(0);
        }

        #title {
            position: fixed;
            top: 20px;
            left: 50%;
            transform: translateX(-50%);
            color: white;
            font-size: 24px;
            text-align: center;
            z-index: 100;
            background: rgba(0, 0, 0, 0.5);
            padding: 10px 30px;
            border-radius: 15px;
            backdrop-filter: blur(10px);
        }

        #instructions {
            position: fixed;
            top: 70px;
            left: 50%;
            transform: translateX(-50%);
            color: rgba(255, 255, 255, 0.7);
            font-size: 14px;
            text-align: center;
            z-index: 100;
            background: rgba(0, 0, 0, 0.5);
            padding: 8px 20px;
            border-radius: 10px;
            backdrop-filter: blur(10px);
        }

        .color-picker {
            width: 30px;
            height: 30px;
            border-radius: 50%;
            border: 2px solid white;
            cursor: pointer;
            margin: 0 5px;
            transition: transform 0.2s;
        }

        .color-picker:hover {
            transform: scale(1.2);
        }

        #color-palette {
            display: flex;
            align-items: center;
            margin-right: 10px;
        }

        @media (max-width: 768px) {
            #controls {
                flex-wrap: wrap;
                justify-content: center;
                bottom: 10px;
                padding: 8px 15px;
            }

            #title {
                font-size: 18px;
                top: 10px;
            }

            #instructions {
                font-size: 12px;
                top: 50px;
            }
        }
    </style>
</head>
<body>
    <div id="container">
        <div id="title">Fluid Simulation</div>
        <div id="instructions">Click and drag to interact • Spacebar for multiple splats • P to pause</div>
        <canvas></canvas>
        <div id="controls">
            <div id="color-palette">
                <div class="color-picker" style="background: #ff0000;" data-hue="0"></div>
                <div class="color-picker" style="background: #00ff00;" data-hue="0.33"></div>
                <div class="color-picker" style="background: #0000ff;" data-hue="0.66"></div>
                <div class="color-picker" style="background: #ffff00;" data-hue="0.16"></div>
                <div class="color-picker" style="background: #ff00ff;" data-hue="0.83"></div>
                <div class="color-picker" style="background: #00ffff;" data-hue="0.5"></div>
                <div class="color-picker" style="background: #ffffff;" data-hue="random"></div>
            </div>
            <button class="control-btn" id="pauseBtn">Pause</button>
        </div>
    </div>

    <script>
        const config = {
            SIM_RESOLUTION: 128,
            DYE_RESOLUTION: 1024,
            CAPTURE_RESOLUTION: 512,
            DENSITY_DISSIPATION: 1,
            VELOCITY_DISSIPATION: 0.2,
            PRESSURE: 0.8,
            PRESSURE_ITERATIONS: 20,
            CURL: 30,
            SPLAT_RADIUS: 0.25,
            SPLAT_FORCE: 6000,
            SHADING: true,
            COLORFUL: true,
            COLOR_UPDATE_SPEED: 10,
            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,
            SUNRAYS: true,
            SUNRAYS_RESOLUTION: 196,
            SUNRAYS_WEIGHT: 1.0,
            RANDOM_COLORS: false,
            SPLAT_HUE: 0.5
        };

        document.addEventListener('DOMContentLoaded', function() {
            document.querySelectorAll('.color-picker').forEach(picker => {
                picker.addEventListener('click', function() {
                    const hue = this.getAttribute('data-hue');
                    if (hue === 'random') {
                        config.RANDOM_COLORS = true;
                        config.SPLAT_HUE = Math.random();
                    } else {
                        config.RANDOM_COLORS = false;
                        config.SPLAT_HUE = parseFloat(hue);
                    }
                });
            });

            document.getElementById('pauseBtn').addEventListener('click', function() {
                config.PAUSED = !config.PAUSED;
                this.textContent = config.PAUSED ? 'Resume' : 'Pause';
            });
        });

        "use strict";

        function resizeCanvas() {
            let width = scaleByPixelRatio(canvas.clientWidth);
            let height = scaleByPixelRatio(canvas.clientHeight);
            if (canvas.width != width || canvas.height != height) {
                canvas.width = width;
                canvas.height = height;
                return true;
            }
            return false;
        }

        function scaleByPixelRatio(input) {
            let pixelRatio = window.devicePixelRatio || 1;
            return Math.floor(input * pixelRatio);
        }

        const canvas = document.getElementsByTagName("canvas")[0];
        resizeCanvas();

        runSimulation(config);

        function runSimulation(config) {
            function pointerPrototype() {
                this.id = -1;
                this.texcoordX = 0;
                this.texcoordY = 0;
                this.prevTexcoordX = 0;
                this.prevTexcoordY = 0;
                this.deltaX = 0;
                this.deltaY = 0;
                this.down = false;
                this.moved = false;
                this.color = [30, 0, 300];
            }

            let pointers = [];
            let splatStack = [];
            pointers.push(new pointerPrototype());

            const { gl, ext } = getWebGLContext(canvas);

            if (isMobile()) {
                config.DYE_RESOLUTION = 512;
            }
            if (!ext.supportLinearFiltering) {
                config.DYE_RESOLUTION = 512;
                config.SHADING = false;
                config.BLOOM = false;
                config.SUNRAYS = false;
            }

            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);
                }

                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
                );

                let status = gl.checkFramebufferStatus(gl.FRAMEBUFFER);
                return status == gl.FRAMEBUFFER_COMPLETE;
            }

            function isMobile() {
                return /Mobi|Android/i.test(navigator.userAgent);
            }

            function captureScreenshot() {
                let res = getResolution(config.CAPTURE_RESOLUTION);
                let target = createFBO(
                    res.width,
                    res.height,
                    ext.formatRGBA.internalFormat,
                    ext.formatRGBA.format,
                    ext.halfFloatTexType,
                    gl.NEAREST
                );
                render(target);

                let texture = framebufferToTexture(target);
                texture = normalizeTexture(texture, target.width, target.height);

                let captureCanvas = textureToCanvas(texture, target.width, target.height);
                let datauri = captureCanvas.toDataURL();
                downloadURI("fluid.png", datauri);
                URL.revokeObjectURL(datauri);
            }

            function framebufferToTexture(target) {
                gl.bindFramebuffer(gl.FRAMEBUFFER, target.fbo);
                let length = target.width * target.height * 4;
                let texture = new Float32Array(length);
                gl.readPixels(
                    0,
                    0,
                    target.width,
                    target.height,
                    gl.RGBA,
                    gl.FLOAT,
                    texture
                );
                return texture;
            }

            function normalizeTexture(texture, width, height) {
                let result = new Uint8Array(texture.length);
                let id = 0;
                for (let i = height - 1; i >= 0; i--) {
                    for (let j = 0; j < width; j++) {
                        let nid = i * width * 4 + j * 4;
                        result[nid + 0] = clamp01(texture[id + 0]) * 255;
                        result[nid + 1] = clamp01(texture[id + 1]) * 255;
                        result[nid + 2] = clamp01(texture[id + 2]) * 255;
                        result[nid + 3] = clamp01(texture[id + 3]) * 255;
                        id += 4;
                    }
                }
                return result;
            }

            function clamp01(input) {
                return Math.min(Math.max(input, 0), 1);
            }

            function textureToCanvas(texture, width, height) {
                let captureCanvas = document.createElement("canvas");
                let ctx = captureCanvas.getContext("2d");
                captureCanvas.width = width;
                captureCanvas.height = height;

                let imageData = ctx.createImageData(width, height);
                imageData.data.set(texture);
                ctx.putImageData(imageData, 0, 0);

                return captureCanvas;
            }

            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);
            }

            class Material {
                constructor(vertexShader, fragmentShaderSource) {
                    this.vertexShader = vertexShader;
                    this.fragmentShaderSource = fragmentShaderSource;
                    this.programs = [];
                    this.activeProgram = null;
                    this.uniforms = [];
                }

                setKeywords(keywords) {
                    let hash = 0;
                    for (let i = 0; i < keywords.length; i++) hash += hashCode(keywords[i]);

                    let program = this.programs[hash];
                    if (program == null) {
                        let fragmentShader = compileShader(
                            gl.FRAGMENT_SHADER,
                            this.fragmentShaderSource,
                            keywords
                        );
                        program = createProgram(this.vertexShader, fragmentShader);
                        this.programs[hash] = program;
                    }

                    if (program == this.activeProgram) return;

                    this.uniforms = getUniforms(program);
                    this.activeProgram = program;
                }

                bind() {
                    gl.useProgram(this.activeProgram);
                }
            }

            class Program {
                constructor(vertexShader, fragmentShader) {
                    this.uniforms = {};
                    this.program = createProgram(vertexShader, fragmentShader);
                    this.uniforms = getUniforms(this.program);
                }

                bind() {
                    gl.useProgram(this.program);
                }
            }

            function createProgram(vertexShader, fragmentShader) {
                let program = gl.createProgram();
                gl.attachShader(program, vertexShader);
                gl.attachShader(program, fragmentShader);
                gl.linkProgram(program);

                if (!gl.getProgramParameter(program, gl.LINK_STATUS))
                    console.trace(gl.getProgramInfoLog(program));

                return program;
            }

            function getUniforms(program) {
                let uniforms = [];
                let uniformCount = gl.getProgramParameter(program, gl.ACTIVE_UNIFORMS);
                for (let i = 0; i < uniformCount; i++) {
                    let uniformName = gl.getActiveUniform(program, i).name;
                    uniforms[uniformName] = gl.getUniformLocation(program, uniformName);
                }
                return uniforms;
            }

            function compileShader(type, source, keywords) {
                source = addKeywords(source, keywords);

                const shader = gl.createShader(type);
                gl.shaderSource(shader, source);
                gl.compileShader(shader);

                if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS))
                    console.trace(gl.getShaderInfoLog(shader));

                return shader;
            }

            function addKeywords(source, keywords) {
                if (keywords == null) return source;
                let keywordsString = "";
                keywords.forEach((keyword) => {
                    keywordsString += "#define " + keyword + "\n";
                });
                return keywordsString + source;
            }

            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 blurVertexShader = compileShader(
                gl.VERTEX_SHADER,
                `
                precision highp float;

                attribute vec2 aPosition;
                varying vec2 vUv;
                varying vec2 vL;
                varying vec2 vR;
                uniform vec2 texelSize;

                void main () {
                    vUv = aPosition * 0.5 + 0.5;
                    float offset = 1.33333333;
                    vL = vUv - texelSize * offset;
                    vR = vUv + texelSize * offset;
                    gl_Position = vec4(aPosition, 0.0, 1.0);
                }
            `
            );

            const blurShader = compileShader(
                gl.FRAGMENT_SHADER,
                `
                precision mediump float;
                precision mediump sampler2D;

                varying vec2 vUv;
                varying vec2 vL;
                varying vec2 vR;
                uniform sampler2D uTexture;

                void main () {
                    vec4 sum = texture2D(uTexture, vUv) * 0.29411764;
                    sum += texture2D(uTexture, vL) * 0.35294117;
                    sum += texture2D(uTexture, vR) * 0.35294117;
                    gl_FragColor = sum;
                }
            `
            );

            const copyShader = compileShader(
                gl.FRAGMENT_SHADER,
                `
                precision mediump float;
                precision mediump sampler2D;

                varying highp vec2 vUv;
                uniform sampler2D uTexture;

                void main () {
                    gl_FragColor = texture2D(uTexture, vUv);
                }
            `
            );

            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 checkerboardShader = 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 displayShaderSource = `
                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 uSunrays;
                uniform sampler2D uDithering;
                uniform vec2 ditherScale;
                uniform vec2 texelSize;

                vec3 linearToGamma (vec3 color) {
                    color = max(color, vec3(0));
                    return max(1.055 * pow(color, vec3(0.416666667)) - 0.055, vec3(0));
                }

                void main () {
                    vec3 c = texture2D(uTexture, vUv).rgb;

                #ifdef SHADING
                    vec3 lc = texture2D(uTexture, vL).rgb;
                    vec3 rc = texture2D(uTexture, vR).rgb;
                    vec3 tc = texture2D(uTexture, vT).rgb;
                    vec3 bc = texture2D(uTexture, vB).rgb;

                    float dx = length(rc) - length(lc);
                    float dy = length(tc) - length(bc);

                    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;
                #endif

                #ifdef BLOOM
                    vec3 bloom = texture2D(uBloom, vUv).rgb;
                #endif

                #ifdef SUNRAYS
                    float sunrays = texture2D(uSunrays, vUv).r;
                    c *= sunrays;
                #ifdef BLOOM
                    bloom *= sunrays;
                #endif
                #endif

                #ifdef BLOOM
                    float noise = texture2D(uDithering, vUv * ditherScale).r;
                    noise = noise * 2.0 - 1.0;
                    bloom += noise / 255.0;
                    bloom = linearToGamma(bloom);
                    c += bloom;
                #endif

                    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 sunraysMaskShader = compileShader(
                gl.FRAGMENT_SHADER,
                `
                precision highp float;
                precision highp sampler2D;

                varying vec2 vUv;
                uniform sampler2D uTexture;

                void main () {
                    vec4 c = texture2D(uTexture, vUv);
                    float br = max(c.r, max(c.g, c.b));
                    c.a = 1.0 - min(max(br * 20.0, 0.0), 0.8);
                    gl_FragColor = c;
                }
            `
            );

            const sunraysShader = compileShader(
                gl.FRAGMENT_SHADER,
                `
                precision highp float;
                precision highp sampler2D;

                varying vec2 vUv;
                uniform sampler2D uTexture;
                uniform float weight;

                #define ITERATIONS 16

                void main () {
                    float Density = 0.3;
                    float Decay = 0.95;
                    float Exposure = 0.7;

                    vec2 coord = vUv;
                    vec2 dir = vUv - 0.5;

                    dir *= 1.0 / float(ITERATIONS) * Density;
                    float illuminationDecay = 1.0;

                    float color = texture2D(uTexture, vUv).a;

                    for (int i = 0; i < ITERATIONS; i++)
                    {
                        coord -= dir;
                        float col = texture2D(uTexture, coord).a;
                        color += col * illuminationDecay * weight;
                        illuminationDecay *= Decay;
                    }

                    gl_FragColor = vec4(color * Exposure, 0.0, 0.0, 1.0);
                }
            `
            );

            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 advectionShader = 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 () {
                #ifdef MANUAL_FILTERING
                    vec2 coord = vUv - dt * bilerp(uVelocity, vUv, texelSize).xy * texelSize;
                    vec4 result = bilerp(uSource, coord, dyeTexelSize);
                #else
                    vec2 coord = vUv - dt * texture2D(uVelocity, vUv).xy * texelSize;
                    vec4 result = texture2D(uSource, coord);
                #endif
                    float decay = 1.0 + dissipation * dt;
                    gl_FragColor = result / decay;
                }`,
                ext.supportLinearFiltering ? null : ["MANUAL_FILTERING"]
            );

            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 velocity = texture2D(uVelocity, vUv).xy;
                    velocity += force * dt;
                    velocity = min(max(velocity, -1000.0), 1000.0);
                    gl_FragColor = vec4(velocity, 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;

                void main () {
                    float L = texture2D(uPressure, vL).x;
                    float R = texture2D(uPressure, vR).x;
                    float T = texture2D(uPressure, vT).x;
                    float B = texture2D(uPressure, 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;

                void main () {
                    float L = texture2D(uPressure, vL).x;
                    float R = texture2D(uPressure, vR).x;
                    float T = texture2D(uPressure, vT).x;
                    float B = texture2D(uPressure, 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 (target, clear = false) => {
                    if (target == null) {
                        gl.viewport(0, 0, gl.drawingBufferWidth, gl.drawingBufferHeight);
                        gl.bindFramebuffer(gl.FRAMEBUFFER, null);
                    } else {
                        gl.viewport(0, 0, target.width, target.height);
                        gl.bindFramebuffer(gl.FRAMEBUFFER, target.fbo);
                    }
                    if (clear) {
                        gl.clearColor(0.0, 0.0, 0.0, 1.0);
                        gl.clear(gl.COLOR_BUFFER_BIT);
                    }
                    gl.drawElements(gl.TRIANGLES, 6, gl.UNSIGNED_SHORT, 0);
                };
            })();

            function CHECK_FRAMEBUFFER_STATUS() {
                let status = gl.checkFramebufferStatus(gl.FRAMEBUFFER);
                if (status != gl.FRAMEBUFFER_COMPLETE)
                    console.trace("Framebuffer error: " + status);
            }

            let dye;
            let velocity;
            let divergence;
            let curl;
            let pressure;
            let bloom;
            let bloomFramebuffers = [];
            let sunrays;
            let sunraysTemp;

            function createDitheringTexture() {
                const size = 64;
                const 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.REPEAT);
                gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.REPEAT);

                const data = new Uint8Array(size * size);
                for (let i = 0; i < size * size; i++) {
                    data[i] = Math.floor(Math.random() * 256);
                }

                gl.texImage2D(
                    gl.TEXTURE_2D,
                    0,
                    gl.LUMINANCE,
                    size,
                    size,
                    0,
                    gl.LUMINANCE,
                    gl.UNSIGNED_BYTE,
                    data
                );

                return {
                    texture,
                    width: size,
                    height: size,
                    attach(id) {
                        gl.activeTexture(gl.TEXTURE0 + id);
                        gl.bindTexture(gl.TEXTURE_2D, texture);
                        return id;
                    },
                };
            }

            let ditheringTexture = createDitheringTexture();

            const blurProgram = new Program(blurVertexShader, blurShader);
            const copyProgram = new Program(baseVertexShader, copyShader);
            const clearProgram = new Program(baseVertexShader, clearShader);
            const colorProgram = new Program(baseVertexShader, colorShader);
            const checkerboardProgram = new Program(baseVertexShader, checkerboardShader);
            const bloomPrefilterProgram = new Program(
                baseVertexShader,
                bloomPrefilterShader
            );
            const bloomBlurProgram = new Program(baseVertexShader, bloomBlurShader);
            const bloomFinalProgram = new Program(baseVertexShader, bloomFinalShader);
            const sunraysMaskProgram = new Program(baseVertexShader, sunraysMaskShader);
            const sunraysProgram = new Program(baseVertexShader, sunraysShader);
            const splatProgram = new Program(baseVertexShader, splatShader);
            const advectionProgram = new Program(baseVertexShader, advectionShader);
            const divergenceProgram = new Program(baseVertexShader, divergenceShader);
            const curlProgram = new Program(baseVertexShader, curlShader);
            const vorticityProgram = new Program(baseVertexShader, vorticityShader);
            const pressureProgram = new Program(baseVertexShader, pressureShader);
            const gradienSubtractProgram = new Program(
                baseVertexShader,
                gradientSubtractShader
            );

            const displayMaterial = new Material(baseVertexShader, displayShaderSource);

            function initFramebuffers() {
                let simRes = getResolution(config.SIM_RESOLUTION);
                let dyeRes = getResolution(config.DYE_RESOLUTION);

                const texType = ext.halfFloatTexType;
                const rgba = ext.formatRGBA;
                const rg = ext.formatRG;
                const r = ext.formatR;
                const filtering = ext.supportLinearFiltering ? gl.LINEAR : gl.NEAREST;

                gl.disable(gl.BLEND);

                if (dye == null)
                    dye = createDoubleFBO(
                        dyeRes.width,
                        dyeRes.height,
                        rgba.internalFormat,
                        rgba.format,
                        texType,
                        filtering
                    );
                else
                    dye = resizeDoubleFBO(
                        dye,
                        dyeRes.width,
                        dyeRes.height,
                        rgba.internalFormat,
                        rgba.format,
                        texType,
                        filtering
                    );

                if (velocity == null)
                    velocity = createDoubleFBO(
                        simRes.width,
                        simRes.height,
                        rg.internalFormat,
                        rg.format,
                        texType,
                        filtering
                    );
                else
                    velocity = resizeDoubleFBO(
                        velocity,
                        simRes.width,
                        simRes.height,
                        rg.internalFormat,
                        rg.format,
                        texType,
                        filtering
                    );

                divergence = createFBO(
                    simRes.width,
                    simRes.height,
                    r.internalFormat,
                    r.format,
                    texType,
                    gl.NEAREST
                );
                curl = createFBO(
                    simRes.width,
                    simRes.height,
                    r.internalFormat,
                    r.format,
                    texType,
                    gl.NEAREST
                );
                pressure = createDoubleFBO(
                    simRes.width,
                    simRes.height,
                    r.internalFormat,
                    r.format,
                    texType,
                    gl.NEAREST
                );

                initBloomFramebuffers();
                initSunraysFramebuffers();
            }

            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 initSunraysFramebuffers() {
                let res = getResolution(config.SUNRAYS_RESOLUTION);

                const texType = ext.halfFloatTexType;
                const r = ext.formatR;
                const filtering = ext.supportLinearFiltering ? gl.LINEAR : gl.NEAREST;

                sunrays = createFBO(
                    res.width,
                    res.height,
                    r.internalFormat,
                    r.format,
                    texType,
                    filtering
                );
                sunraysTemp = createFBO(
                    res.width,
                    res.height,
                    r.internalFormat,
                    r.format,
                    texType,
                    filtering
                );
            }

            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);

                let texelSizeX = 1.0 / w;
                let texelSizeY = 1.0 / h;

                return {
                    texture,
                    fbo,
                    width: w,
                    height: h,
                    texelSizeX,
                    texelSizeY,
                    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 {
                    width: w,
                    height: h,
                    texelSizeX: fbo1.texelSizeX,
                    texelSizeY: fbo1.texelSizeY,
                    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);
                copyProgram.bind();
                gl.uniform1i(copyProgram.uniforms.uTexture, target.attach(0));
                blit(newFBO);
                return newFBO;
            }

            function resizeDoubleFBO(target, w, h, internalFormat, format, type, param) {
                if (target.width == w && target.height == h) return target;
                target.read = resizeFBO(
                    target.read,
                    w,
                    h,
                    internalFormat,
                    format,
                    type,
                    param
                );
                target.write = createFBO(w, h, internalFormat, format, type, param);
                target.width = w;
                target.height = h;
                target.texelSizeX = 1.0 / w;
                target.texelSizeY = 1.0 / h;
                return target;
            }

            function updateKeywords() {
                let displayKeywords = [];
                if (config.SHADING) displayKeywords.push("SHADING");
                if (config.BLOOM) displayKeywords.push("BLOOM");
                if (config.SUNRAYS) displayKeywords.push("SUNRAYS");
                displayMaterial.setKeywords(displayKeywords);
            }

            updateKeywords();
            initFramebuffers();
            multipleSplats(parseInt(Math.random() * 20) + 5);

            let lastUpdateTime = Date.now();
            let colorUpdateTimer = 0.0;
            update();

            function update() {
                const dt = calcDeltaTime();
                if (resizeCanvas()) initFramebuffers();
                updateColors(dt);
                applyInputs();
                if (!config.PAUSED) step(dt);
                render(null);
                requestAnimationFrame(update);
            }

            function calcDeltaTime() {
                let now = Date.now();
                let dt = (now - lastUpdateTime) / 1000;
                dt = Math.min(dt, 0.016666);
                lastUpdateTime = now;
                return dt;
            }

            function updateColors(dt) {
                if (!config.COLORFUL) return;

                colorUpdateTimer += dt * config.COLOR_UPDATE_SPEED;
                if (colorUpdateTimer >= 1) {
                    colorUpdateTimer = wrap(colorUpdateTimer, 0, 1);
                    pointers.forEach((p) => {
                        p.color = generateColor();
                    });
                }
            }

            function applyInputs() {
                if (splatStack.length > 0) multipleSplats(splatStack.pop());

                pointers.forEach((p) => {
                    if (p.moved) {
                        p.moved = false;
                        splatPointer(p);
                    }
                });
            }

            function step(dt) {
                gl.disable(gl.BLEND);

                curlProgram.bind();
                gl.uniform2f(
                    curlProgram.uniforms.texelSize,
                    velocity.texelSizeX,
                    velocity.texelSizeY
                );
                gl.uniform1i(curlProgram.uniforms.uVelocity, velocity.read.attach(0));
                blit(curl);

                vorticityProgram.bind();
                gl.uniform2f(
                    vorticityProgram.uniforms.texelSize,
                    velocity.texelSizeX,
                    velocity.texelSizeY
                );
                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);
                velocity.swap();

                divergenceProgram.bind();
                gl.uniform2f(
                    divergenceProgram.uniforms.texelSize,
                    velocity.texelSizeX,
                    velocity.texelSizeY
                );
                gl.uniform1i(divergenceProgram.uniforms.uVelocity, velocity.read.attach(0));
                blit(divergence);

                clearProgram.bind();
                gl.uniform1i(clearProgram.uniforms.uTexture, pressure.read.attach(0));
                gl.uniform1f(clearProgram.uniforms.value, config.PRESSURE);
                blit(pressure.write);
                pressure.swap();

                pressureProgram.bind();
                gl.uniform2f(
                    pressureProgram.uniforms.texelSize,
                    velocity.texelSizeX,
                    velocity.texelSizeY
                );
                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);
                    pressure.swap();
                }

                gradienSubtractProgram.bind();
                gl.uniform2f(
                    gradienSubtractProgram.uniforms.texelSize,
                    velocity.texelSizeX,
                    velocity.texelSizeY
                );
                gl.uniform1i(
                    gradienSubtractProgram.uniforms.uPressure,
                    pressure.read.attach(0)
                );
                gl.uniform1i(
                    gradienSubtractProgram.uniforms.uVelocity,
                    velocity.read.attach(1)
                );
                blit(velocity.write);
                velocity.swap();

                advectionProgram.bind();
                gl.uniform2f(
                    advectionProgram.uniforms.texelSize,
                    velocity.texelSizeX,
                    velocity.texelSizeY
                );
                if (!ext.supportLinearFiltering)
                    gl.uniform2f(
                        advectionProgram.uniforms.dyeTexelSize,
                        velocity.texelSizeX,
                        velocity.texelSizeY
                    );
                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);
                velocity.swap();

                if (!ext.supportLinearFiltering)
                    gl.uniform2f(
                        advectionProgram.uniforms.dyeTexelSize,
                        dye.texelSizeX,
                        dye.texelSizeY
                    );
                gl.uniform1i(advectionProgram.uniforms.uVelocity, velocity.read.attach(0));
                gl.uniform1i(advectionProgram.uniforms.uSource, dye.read.attach(1));
                gl.uniform1f(
                    advectionProgram.uniforms.dissipation,
                    config.DENSITY_DISSIPATION
                );
                blit(dye.write);
                dye.swap();
            }

            function render(target) {
                if (config.BLOOM) applyBloom(dye.read, bloom);
                if (config.SUNRAYS) {
                    applySunrays(dye.read, dye.write, sunrays);
                    blur(sunrays, sunraysTemp, 1);
                }

                if (target == null || !config.TRANSPARENT) {
                    gl.blendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
                    gl.enable(gl.BLEND);
                } else {
                    gl.disable(gl.BLEND);
                }

                if (!config.TRANSPARENT)
                    drawColor(target, normalizeColor(config.BACK_COLOR));
                if (target == null && config.TRANSPARENT) drawCheckerboard(target);
                drawDisplay(target);
            }

            function drawColor(target, color) {
                colorProgram.bind();
                gl.uniform4f(colorProgram.uniforms.color, color.r, color.g, color.b, 1);
                blit(target);
            }

            function drawCheckerboard(target) {
                checkerboardProgram.bind();
                gl.uniform1f(
                    checkerboardProgram.uniforms.aspectRatio,
                    canvas.width / canvas.height
                );
                blit(target);
            }

            function drawDisplay(target) {
                let width = target == null ? gl.drawingBufferWidth : target.width;
                let height = target == null ? gl.drawingBufferHeight : target.height;

                displayMaterial.bind();
                if (config.SHADING)
                    gl.uniform2f(
                        displayMaterial.uniforms.texelSize,
                        1.0 / width,
                        1.0 / height
                    );
                gl.uniform1i(displayMaterial.uniforms.uTexture, dye.read.attach(0));
                if (config.BLOOM) {
                    gl.uniform1i(displayMaterial.uniforms.uBloom, bloom.attach(1));
                    gl.uniform1i(
                        displayMaterial.uniforms.uDithering,
                        ditheringTexture.attach(2)
                    );
                    let scale = getTextureScale(ditheringTexture, width, height);
                    gl.uniform2f(displayMaterial.uniforms.ditherScale, scale.x, scale.y);
                }
                if (config.SUNRAYS)
                    gl.uniform1i(displayMaterial.uniforms.uSunrays, sunrays.attach(3));
                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));
                blit(last);

                bloomBlurProgram.bind();
                for (let i = 0; i < bloomFramebuffers.length; i++) {
                    let dest = bloomFramebuffers[i];
                    gl.uniform2f(
                        bloomBlurProgram.uniforms.texelSize,
                        last.texelSizeX,
                        last.texelSizeY
                    );
                    gl.uniform1i(bloomBlurProgram.uniforms.uTexture, last.attach(0));
                    blit(dest);
                    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,
                        last.texelSizeX,
                        last.texelSizeY
                    );
                    gl.uniform1i(bloomBlurProgram.uniforms.uTexture, last.attach(0));
                    gl.viewport(0, 0, baseTex.width, baseTex.height);
                    blit(baseTex);
                    last = baseTex;
                }

                gl.disable(gl.BLEND);
                bloomFinalProgram.bind();
                gl.uniform2f(
                    bloomFinalProgram.uniforms.texelSize,
                    last.texelSizeX,
                    last.texelSizeY
                );
                gl.uniform1i(bloomFinalProgram.uniforms.uTexture, last.attach(0));
                gl.uniform1f(bloomFinalProgram.uniforms.intensity, config.BLOOM_INTENSITY);
                blit(destination);
            }

            function applySunrays(source, mask, destination) {
                gl.disable(gl.BLEND);
                sunraysMaskProgram.bind();
                gl.uniform1i(sunraysMaskProgram.uniforms.uTexture, source.attach(0));
                blit(mask);

                sunraysProgram.bind();
                gl.uniform1f(sunraysProgram.uniforms.weight, config.SUNRAYS_WEIGHT);
                gl.uniform1i(sunraysProgram.uniforms.uTexture, mask.attach(0));
                blit(destination);
            }

            function blur(target, temp, iterations) {
                blurProgram.bind();
                for (let i = 0; i < iterations; i++) {
                    gl.uniform2f(blurProgram.uniforms.texelSize, target.texelSizeX, 0.0);
                    gl.uniform1i(blurProgram.uniforms.uTexture, target.attach(0));
                    blit(temp);

                    gl.uniform2f(blurProgram.uniforms.texelSize, 0.0, target.texelSizeY);
                    gl.uniform1i(blurProgram.uniforms.uTexture, temp.attach(0));
                    blit(target);
                }
            }

            function splatPointer(pointer) {
                let dx = pointer.deltaX * config.SPLAT_FORCE;
                let dy = pointer.deltaY * config.SPLAT_FORCE;
                splat(pointer.texcoordX, pointer.texcoordY, dx, dy, pointer.color);
            }

            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 = Math.random();
                    const y = Math.random();
                    const dx = 1000 * (Math.random() - 0.5);
                    const dy = 1000 * (Math.random() - 0.5);
                    splat(x, y, dx, dy, color);
                }
            }

            function splat(x, y, dx, dy, color) {
                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, y);
                gl.uniform3f(splatProgram.uniforms.color, dx, dy, 0.0);
                gl.uniform1f(
                    splatProgram.uniforms.radius,
                    correctRadius(config.SPLAT_RADIUS / 100.0)
                );
                blit(velocity.write);
                velocity.swap();

                gl.uniform1i(splatProgram.uniforms.uTarget, dye.read.attach(0));
                gl.uniform3f(splatProgram.uniforms.color, color.r, color.g, color.b);
                blit(dye.write);
                dye.swap();
            }

            function correctRadius(radius) {
                let aspectRatio = canvas.width / canvas.height;
                if (aspectRatio > 1) radius *= aspectRatio;
                return radius;
            }

            canvas.addEventListener("mousemove", (e) => {
                let pointer = pointers[0];
                let posX = scaleByPixelRatio(e.offsetX);
                let posY = scaleByPixelRatio(e.offsetY);

                if (!pointer.down) {
                    updatePointerDownData(pointer, -1, posX, posY);
                }

                updatePointerMoveData(pointer, posX, posY);
            });

            window.addEventListener("mouseup", () => {
                updatePointerUpData(pointers[0]);
            });

            canvas.addEventListener("touchstart", (e) => {
                e.preventDefault();
                const touches = e.targetTouches;
                while (touches.length >= pointers.length)
                    pointers.push(new pointerPrototype());
                for (let i = 0; i < touches.length; i++) {
                    let posX = scaleByPixelRatio(touches[i].pageX);
                    let posY = scaleByPixelRatio(touches[i].pageY);
                    updatePointerDownData(pointers[i + 1], touches[i].identifier, posX, posY);
                }
            });

            canvas.addEventListener(
                "touchmove",
                (e) => {
                    e.preventDefault();
                    const touches = e.targetTouches;
                    for (let i = 0; i < touches.length; i++) {
                        let pointer = pointers[i + 1];
                        if (!pointer.down) continue;
                        let posX = scaleByPixelRatio(touches[i].pageX);
                        let posY = scaleByPixelRatio(touches[i].pageY);
                        updatePointerMoveData(pointer, posX, posY);
                    }
                },
                false
            );

            window.addEventListener("touchend", (e) => {
                const touches = e.changedTouches;
                for (let i = 0; i < touches.length; i++) {
                    let pointer = pointers.find((p) => p.id == touches[i].identifier);
                    if (pointer == null) continue;
                    updatePointerUpData(pointer);
                }
            });

            window.addEventListener("keydown", (e) => {
                if (e.code === "KeyP") config.PAUSED = !config.PAUSED;
                if (e.key === " ") splatStack.push(parseInt(Math.random() * 20) + 5);
            });

            function updatePointerDownData(pointer, id, posX, posY) {
                pointer.id = id;
                pointer.down = true;
                pointer.moved = false;
                pointer.texcoordX = posX / canvas.width;
                pointer.texcoordY = 1.0 - posY / canvas.height;
                pointer.prevTexcoordX = pointer.texcoordX;
                pointer.prevTexcoordY = pointer.texcoordY;
                pointer.deltaX = 0;
                pointer.deltaY = 0;
                pointer.color = generateColor();
            }

            function updatePointerMoveData(pointer, posX, posY) {
                pointer.prevTexcoordX = pointer.texcoordX;
                pointer.prevTexcoordY = pointer.texcoordY;
                pointer.texcoordX = posX / canvas.width;
                pointer.texcoordY = 1.0 - posY / canvas.height;
                pointer.deltaX = correctDeltaX(pointer.texcoordX - pointer.prevTexcoordX);
                pointer.deltaY = correctDeltaY(pointer.texcoordY - pointer.prevTexcoordY);
                pointer.moved =
                    Math.abs(pointer.deltaX) > 0 || Math.abs(pointer.deltaY) > 0;
            }

            function updatePointerUpData(pointer) {
                pointer.down = false;
            }

            function correctDeltaX(delta) {
                let aspectRatio = canvas.width / canvas.height;
                if (aspectRatio < 1) delta *= aspectRatio;
                return delta;
            }

            function correctDeltaY(delta) {
                let aspectRatio = canvas.width / canvas.height;
                if (aspectRatio > 1) delta /= aspectRatio;
                return delta;
            }

            function generateColor() {
                if (config.RANDOM_COLORS) {
                    let c = HSVtoRGB(Math.random(), 1.0, 1.0);
                    c.r *= 0.15;
                    c.g *= 0.15;
                    c.b *= 0.15;
                    return c;
                } else {
                    let c = HSVtoRGB(config.SPLAT_HUE, 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 normalizeColor(input) {
                let output = {
                    r: input.r / 255,
                    g: input.g / 255,
                    b: input.b / 255,
                };
                return output;
            }

            function wrap(value, min, max) {
                let range = max - min;
                if (range == 0) return min;
                return ((value - min) % range) + min;
            }

            function getResolution(resolution) {
                let aspectRatio = gl.drawingBufferWidth / gl.drawingBufferHeight;
                if (aspectRatio < 1) aspectRatio = 1.0 / aspectRatio;

                let min = Math.round(resolution);
                let max = Math.round(resolution * aspectRatio);

                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,
                };
            }

            function hashCode(s) {
                if (s.length == 0) return 0;
                let hash = 0;
                for (let i = 0; i < s.length; i++) {
                    hash = (hash << 5) - hash + s.charCodeAt(i);
                    hash |= 0;
                }
                return hash;
            }
        }
    </script>
</body>
</html>