'use strict';
const canvas = document.getElementsByTagName('canvas')[0];
resizeCanvas();

let config = {
    SIM_RESOLUTION: 128,
    DYE_RESOLUTION: 1024,
    CAPTURE_RESOLUTION: 512,
    DENSITY_DISSIPATION: 0.58,
    VELOCITY_DISSIPATION: 0.57,
    PRESSURE: 0.9,
    PRESSURE_ITERATIONS: 25,
    CURL: 1,
    SPLAT_RADIUS: 0.01,
    SPLAT_FORCE: 6000,
    SHADING: true,
    COLORFUL: true,
    COLOR_UPDATE_SPEED: .9,
    BACK_COLOR: { r: 0, g: 0, b: 0 },
    TRANSPARENT: true,
    SUNRAYS: true,
    SUNRAYS_RESOLUTION: 196,
    SUNRAYS_WEIGHT: 1.0,
}

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];
}

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

var ref = getWebGLContext(canvas);
var gl = ref.gl;
var ext = ref.ext;

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


function getWebGLContext (canvas) {
    var params = { alpha: true, depth: false, stencil: false, antialias: false, preserveDrawingBuffer: false };

    var gl = canvas.getContext('webgl2', params);
    var isWebGL2 = !!gl;
    if (!isWebGL2)
        { gl = canvas.getContext('webgl', params) || canvas.getContext('experimental-webgl', params); }

    var halfFloat;
    var 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);

    var halfFloatTexType = isWebGL2 ? gl.HALF_FLOAT : halfFloat.HALF_FLOAT_OES;
    var formatRGBA;
    var formatRG;
    var 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: gl,
        ext: {
            formatRGBA: formatRGBA,
            formatRG: formatRG,
            formatR: formatR,
            halfFloatTexType: halfFloatTexType,
            supportLinearFiltering: 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: internalFormat,
        format: format
    }
}

function supportRenderTextureFormat (gl, internalFormat, format, type) {
    var 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);

    var fbo = gl.createFramebuffer();
    gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
    gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, 0);

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



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

function normalizeTexture (texture, width, height) {
    var result = new Uint8Array(texture.length);
    var id = 0;
    for (var i = height - 1; i >= 0; i--) {
        for (var j = 0; j < width; j++) {
            var 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) {
    var captureCanvas = document.createElement('canvas');
    var ctx = captureCanvas.getContext('2d');
    captureCanvas.width = width;
    captureCanvas.height = height;

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

    return captureCanvas;
}

function downloadURI (filename, uri) {
    var link = document.createElement('a');
    link.download = filename;
    link.href = uri;
    document.body.appendChild(link);
    link.click();
    document.body.removeChild(link);
}

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

Material.prototype.setKeywords = function setKeywords (keywords) {
    var hash = 0;
    for (var i = 0; i < keywords.length; i++)
        { hash += hashCode(keywords[i]); }

    var program = this.programs[hash];
    if (program == null)
    {
        var 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;
};

Material.prototype.bind = function bind () {
    gl.useProgram(this.activeProgram);
};

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

Program.prototype.bind = function bind () {
    gl.useProgram(this.program);
};

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

    if (!gl.getProgramParameter(program, gl.LINK_STATUS))
        { throw gl.getProgramInfoLog(program); }

    return program;
}

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

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

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

    if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS))
        { throw gl.getShaderInfoLog(shader); }

    return shader;
};

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

var baseVertexShader = compileShader(gl.VERTEX_SHADER, "\n    precision highp float;\n\n    attribute vec2 aPosition;\n    varying vec2 vUv;\n    varying vec2 vL;\n    varying vec2 vR;\n    varying vec2 vT;\n    varying vec2 vB;\n    uniform vec2 texelSize;\n\n    void main () {\n        vUv = aPosition * 0.5 + 0.5;\n        vL = vUv - vec2(texelSize.x, 0.0);\n        vR = vUv + vec2(texelSize.x, 0.0);\n        vT = vUv + vec2(0.0, texelSize.y);\n        vB = vUv - vec2(0.0, texelSize.y);\n        gl_Position = vec4(aPosition, 0.0, 1.0);\n    }\n");

var blurVertexShader = compileShader(gl.VERTEX_SHADER, "\n    precision highp float;\n\n    attribute vec2 aPosition;\n    varying vec2 vUv;\n    varying vec2 vL;\n    varying vec2 vR;\n    uniform vec2 texelSize;\n\n    void main () {\n        vUv = aPosition * 0.5 + 0.5;\n        float offset = 1.33333333;\n        vL = vUv - texelSize * offset;\n        vR = vUv + texelSize * offset;\n        gl_Position = vec4(aPosition, 0.0, 1.0);\n    }\n");

var blurShader = compileShader(gl.FRAGMENT_SHADER, "\n    precision mediump float;\n    precision mediump sampler2D;\n\n    varying vec2 vUv;\n    varying vec2 vL;\n    varying vec2 vR;\n    uniform sampler2D uTexture;\n\n    void main () {\n        vec4 sum = texture2D(uTexture, vUv) * 0.29411764;\n        sum += texture2D(uTexture, vL) * 0.35294117;\n        sum += texture2D(uTexture, vR) * 0.35294117;\n        gl_FragColor = sum;\n    }\n");

var copyShader = compileShader(gl.FRAGMENT_SHADER, "\n    precision mediump float;\n    precision mediump sampler2D;\n\n    varying highp vec2 vUv;\n    uniform sampler2D uTexture;\n\n    void main () {\n        gl_FragColor = texture2D(uTexture, vUv);\n    }\n");

var clearShader = compileShader(gl.FRAGMENT_SHADER, "\n    precision mediump float;\n    precision mediump sampler2D;\n\n    varying highp vec2 vUv;\n    uniform sampler2D uTexture;\n    uniform float value;\n\n    void main () {\n        gl_FragColor = value * texture2D(uTexture, vUv);\n    }\n");

var colorShader = compileShader(gl.FRAGMENT_SHADER, "\n    precision mediump float;\n\n    uniform vec4 color;\n\n    void main () {\n        gl_FragColor = color;\n    }\n");



var displayShaderSource = "\n    precision highp float;\n    precision highp sampler2D;\n\n    varying vec2 vUv;\n    varying vec2 vL;\n    varying vec2 vR;\n    varying vec2 vT;\n    varying vec2 vB;\n    uniform sampler2D uTexture;\n    uniform sampler2D uBloom;\n    uniform sampler2D uSunrays;\n    uniform sampler2D uDithering;\n    uniform vec2 ditherScale;\n    uniform vec2 texelSize;\n\n    vec3 linearToGamma (vec3 color) {\n        color = max(color, vec3(0));\n        return max(1.055 * pow(color, vec3(0.416666667)) - 0.055, vec3(0));\n    }\n\n    void main () {\n        vec3 c = texture2D(uTexture, vUv).rgb;\n\n    #ifdef SHADING\n        vec3 lc = texture2D(uTexture, vL).rgb;\n        vec3 rc = texture2D(uTexture, vR).rgb;\n        vec3 tc = texture2D(uTexture, vT).rgb;\n        vec3 bc = texture2D(uTexture, vB).rgb;\n\n        float dx = length(rc) - length(lc);\n        float dy = length(tc) - length(bc);\n\n        vec3 n = normalize(vec3(dx, dy, length(texelSize)));\n        vec3 l = vec3(0.0, 0.0, 1.0);\n\n        float diffuse = clamp(dot(n, l) + 0.7, 0.7, 1.0);\n        c *= diffuse;\n    #endif\n\n    #ifdef BLOOM\n        vec3 bloom = texture2D(uBloom, vUv).rgb;\n    #endif\n\n    #ifdef SUNRAYS\n        float sunrays = texture2D(uSunrays, vUv).r;\n        c *= sunrays;\n    #ifdef BLOOM\n        bloom *= sunrays;\n    #endif\n    #endif\n\n    #ifdef BLOOM\n        float noise = texture2D(uDithering, vUv * ditherScale).r;\n        noise = noise * 2.0 - 1.0;\n        bloom += noise / 255.0;\n        bloom = linearToGamma(bloom);\n        c += bloom;\n    #endif\n\n        float a = max(c.r, max(c.g, c.b));\n        gl_FragColor = vec4(c, a);\n    }\n";

var bloomPrefilterShader = compileShader(gl.FRAGMENT_SHADER, "\n    precision mediump float;\n    precision mediump sampler2D;\n\n    varying vec2 vUv;\n    uniform sampler2D uTexture;\n    uniform vec3 curve;\n    uniform float threshold;\n\n    void main () {\n        vec3 c = texture2D(uTexture, vUv).rgb;\n        float br = max(c.r, max(c.g, c.b));\n        float rq = clamp(br - curve.x, 0.0, curve.y);\n        rq = curve.z * rq * rq;\n        c *= max(rq, br - threshold) / max(br, 0.0001);\n        gl_FragColor = vec4(c, 0.0);\n    }\n");

var bloomBlurShader = compileShader(gl.FRAGMENT_SHADER, "\n    precision mediump float;\n    precision mediump sampler2D;\n\n    varying vec2 vL;\n    varying vec2 vR;\n    varying vec2 vT;\n    varying vec2 vB;\n    uniform sampler2D uTexture;\n\n    void main () {\n        vec4 sum = vec4(0.0);\n        sum += texture2D(uTexture, vL);\n        sum += texture2D(uTexture, vR);\n        sum += texture2D(uTexture, vT);\n        sum += texture2D(uTexture, vB);\n        sum *= 0.25;\n        gl_FragColor = sum;\n    }\n");

var bloomFinalShader = compileShader(gl.FRAGMENT_SHADER, "\n    precision mediump float;\n    precision mediump sampler2D;\n\n    varying vec2 vL;\n    varying vec2 vR;\n    varying vec2 vT;\n    varying vec2 vB;\n    uniform sampler2D uTexture;\n    uniform float intensity;\n\n    void main () {\n        vec4 sum = vec4(0.0);\n        sum += texture2D(uTexture, vL);\n        sum += texture2D(uTexture, vR);\n        sum += texture2D(uTexture, vT);\n        sum += texture2D(uTexture, vB);\n        sum *= 0.25;\n        gl_FragColor = sum * intensity;\n    }\n");

var sunraysMaskShader = compileShader(gl.FRAGMENT_SHADER, "\n    precision highp float;\n    precision highp sampler2D;\n\n    varying vec2 vUv;\n    uniform sampler2D uTexture;\n\n    void main () {\n        vec4 c = texture2D(uTexture, vUv);\n        float br = max(c.r, max(c.g, c.b));\n        c.a = 1.0 - min(max(br * 20.0, 0.0), 0.8);\n        gl_FragColor = c;\n    }\n");

var sunraysShader = compileShader(gl.FRAGMENT_SHADER, "\n    precision highp float;\n    precision highp sampler2D;\n\n    varying vec2 vUv;\n    uniform sampler2D uTexture;\n    uniform float weight;\n\n    #define ITERATIONS 16\n\n    void main () {\n        float Density = 0.3;\n        float Decay = 0.95;\n        float Exposure = 0.7;\n\n        vec2 coord = vUv;\n        vec2 dir = vUv - 0.5;\n\n        dir *= 1.0 / float(ITERATIONS) * Density;\n        float illuminationDecay = 1.0;\n\n        float color = texture2D(uTexture, vUv).a;\n\n        for (int i = 0; i < ITERATIONS; i++)\n        {\n            coord -= dir;\n            float col = texture2D(uTexture, coord).a;\n            color += col * illuminationDecay * weight;\n            illuminationDecay *= Decay;\n        }\n\n        gl_FragColor = vec4(color * Exposure, 0.0, 0.0, 1.0);\n    }\n");

var splatShader = compileShader(gl.FRAGMENT_SHADER, "\n    precision highp float;\n    precision highp sampler2D;\n\n    varying vec2 vUv;\n    uniform sampler2D uTarget;\n    uniform float aspectRatio;\n    uniform vec3 color;\n    uniform vec2 point;\n    uniform float radius;\n\n    void main () {\n        vec2 p = vUv - point.xy;\n        p.x *= aspectRatio;\n        vec3 splat = exp(-dot(p, p) / radius) * color;\n        vec3 base = texture2D(uTarget, vUv).xyz;\n        gl_FragColor = vec4(base + splat, 1.0);\n    }\n");

var advectionShader = compileShader(gl.FRAGMENT_SHADER, "\n    precision highp float;\n    precision highp sampler2D;\n\n    varying vec2 vUv;\n    uniform sampler2D uVelocity;\n    uniform sampler2D uSource;\n    uniform vec2 texelSize;\n    uniform vec2 dyeTexelSize;\n    uniform float dt;\n    uniform float dissipation;\n\n    vec4 bilerp (sampler2D sam, vec2 uv, vec2 tsize) {\n        vec2 st = uv / tsize - 0.5;\n\n        vec2 iuv = floor(st);\n        vec2 fuv = fract(st);\n\n        vec4 a = texture2D(sam, (iuv + vec2(0.5, 0.5)) * tsize);\n        vec4 b = texture2D(sam, (iuv + vec2(1.5, 0.5)) * tsize);\n        vec4 c = texture2D(sam, (iuv + vec2(0.5, 1.5)) * tsize);\n        vec4 d = texture2D(sam, (iuv + vec2(1.5, 1.5)) * tsize);\n\n        return mix(mix(a, b, fuv.x), mix(c, d, fuv.x), fuv.y);\n    }\n\n    void main () {\n    #ifdef MANUAL_FILTERING\n        vec2 coord = vUv - dt * bilerp(uVelocity, vUv, texelSize).xy * texelSize;\n        vec4 result = bilerp(uSource, coord, dyeTexelSize);\n    #else\n        vec2 coord = vUv - dt * texture2D(uVelocity, vUv).xy * texelSize;\n        vec4 result = texture2D(uSource, coord);\n    #endif\n        float decay = 1.0 + dissipation * dt;\n        gl_FragColor = result / decay;\n    }",
    ext.supportLinearFiltering ? null : ['MANUAL_FILTERING']
);

var divergenceShader = compileShader(gl.FRAGMENT_SHADER, "\n    precision mediump float;\n    precision mediump sampler2D;\n\n    varying highp vec2 vUv;\n    varying highp vec2 vL;\n    varying highp vec2 vR;\n    varying highp vec2 vT;\n    varying highp vec2 vB;\n    uniform sampler2D uVelocity;\n\n    void main () {\n        float L = texture2D(uVelocity, vL).x;\n        float R = texture2D(uVelocity, vR).x;\n        float T = texture2D(uVelocity, vT).y;\n        float B = texture2D(uVelocity, vB).y;\n\n        vec2 C = texture2D(uVelocity, vUv).xy;\n        if (vL.x < 0.0) { L = -C.x; }\n        if (vR.x > 1.0) { R = -C.x; }\n        if (vT.y > 1.0) { T = -C.y; }\n        if (vB.y < 0.0) { B = -C.y; }\n\n        float div = 0.5 * (R - L + T - B);\n        gl_FragColor = vec4(div, 0.0, 0.0, 1.0);\n    }\n");

var curlShader = compileShader(gl.FRAGMENT_SHADER, "\n    precision mediump float;\n    precision mediump sampler2D;\n\n    varying highp vec2 vUv;\n    varying highp vec2 vL;\n    varying highp vec2 vR;\n    varying highp vec2 vT;\n    varying highp vec2 vB;\n    uniform sampler2D uVelocity;\n\n    void main () {\n        float L = texture2D(uVelocity, vL).y;\n        float R = texture2D(uVelocity, vR).y;\n        float T = texture2D(uVelocity, vT).x;\n        float B = texture2D(uVelocity, vB).x;\n        float vorticity = R - L - T + B;\n        gl_FragColor = vec4(0.5 * vorticity, 0.0, 0.0, 1.0);\n    }\n");

var vorticityShader = compileShader(gl.FRAGMENT_SHADER, "\n    precision highp float;\n    precision highp sampler2D;\n\n    varying vec2 vUv;\n    varying vec2 vL;\n    varying vec2 vR;\n    varying vec2 vT;\n    varying vec2 vB;\n    uniform sampler2D uVelocity;\n    uniform sampler2D uCurl;\n    uniform float curl;\n    uniform float dt;\n\n    void main () {\n        float L = texture2D(uCurl, vL).x;\n        float R = texture2D(uCurl, vR).x;\n        float T = texture2D(uCurl, vT).x;\n        float B = texture2D(uCurl, vB).x;\n        float C = texture2D(uCurl, vUv).x;\n\n        vec2 force = 0.5 * vec2(abs(T) - abs(B), abs(R) - abs(L));\n        force /= length(force) + 0.0001;\n        force *= curl * C;\n        force.y *= -1.0;\n\n        vec2 vel = texture2D(uVelocity, vUv).xy;\n        gl_FragColor = vec4(vel + force * dt, 0.0, 1.0);\n    }\n");

var pressureShader = compileShader(gl.FRAGMENT_SHADER, "\n    precision mediump float;\n    precision mediump sampler2D;\n\n    varying highp vec2 vUv;\n    varying highp vec2 vL;\n    varying highp vec2 vR;\n    varying highp vec2 vT;\n    varying highp vec2 vB;\n    uniform sampler2D uPressure;\n    uniform sampler2D uDivergence;\n\n    void main () {\n        float L = texture2D(uPressure, vL).x;\n        float R = texture2D(uPressure, vR).x;\n        float T = texture2D(uPressure, vT).x;\n        float B = texture2D(uPressure, vB).x;\n        float C = texture2D(uPressure, vUv).x;\n        float divergence = texture2D(uDivergence, vUv).x;\n        float pressure = (L + R + B + T - divergence) * 0.25;\n        gl_FragColor = vec4(pressure, 0.0, 0.0, 1.0);\n    }\n");

var gradientSubtractShader = compileShader(gl.FRAGMENT_SHADER, "\n    precision mediump float;\n    precision mediump sampler2D;\n\n    varying highp vec2 vUv;\n    varying highp vec2 vL;\n    varying highp vec2 vR;\n    varying highp vec2 vT;\n    varying highp vec2 vB;\n    uniform sampler2D uPressure;\n    uniform sampler2D uVelocity;\n\n    void main () {\n        float L = texture2D(uPressure, vL).x;\n        float R = texture2D(uPressure, vR).x;\n        float T = texture2D(uPressure, vT).x;\n        float B = texture2D(uPressure, vB).x;\n        vec2 velocity = texture2D(uVelocity, vUv).xy;\n        velocity.xy -= vec2(R - L, T - B);\n        gl_FragColor = vec4(velocity, 0.0, 1.0);\n    }\n");

var blit = (function () {
    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 function (destination) {
        gl.bindFramebuffer(gl.FRAMEBUFFER, destination);
        gl.drawElements(gl.TRIANGLES, 6, gl.UNSIGNED_SHORT, 0);
    }
})();

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

//var ditheringTexture = createTextureAsync('LDR_LLL1_0.png');

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

var displayMaterial = new Material(baseVertexShader, displayShaderSource);

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

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

    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 () {
    var res = getResolution(config.BLOOM_RESOLUTION);

    var texType = ext.halfFloatTexType;
    var rgba = ext.formatRGBA;
    var filtering = ext.supportLinearFiltering ? gl.LINEAR : gl.NEAREST;

    bloom = createFBO(res.width, res.height, rgba.internalFormat, rgba.format, texType, filtering);

    bloomFramebuffers.length = 0;
    for (var i = 0; i < config.BLOOM_ITERATIONS; i++)
    {
        var width = res.width >> (i + 1);
        var height = res.height >> (i + 1);

        if (width < 2 || height < 2) { break; }

        var fbo = createFBO(width, height, rgba.internalFormat, rgba.format, texType, filtering);
        bloomFramebuffers.push(fbo);
    }
}

function initSunraysFramebuffers () {
    var res = getResolution(config.SUNRAYS_RESOLUTION);

    var texType = ext.halfFloatTexType;
    var r = ext.formatR;
    var 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);
    var 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);

    var 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);

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

    return {
        texture: texture,
        fbo: fbo,
        width: w,
        height: h,
        texelSizeX: texelSizeX,
        texelSizeY: texelSizeY,
        attach: function attach (id) {
            gl.activeTexture(gl.TEXTURE0 + id);
            gl.bindTexture(gl.TEXTURE_2D, texture);
            return id;
        }
    };
}

function createDoubleFBO (w, h, internalFormat, format, type, param) {
    var fbo1 = createFBO(w, h, internalFormat, format, type, param);
    var 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: function swap () {
            var temp = fbo1;
            fbo1 = fbo2;
            fbo2 = temp;
        }
    }
}

function resizeFBO (target, w, h, internalFormat, format, type, param) {
    var newFBO = createFBO(w, h, internalFormat, format, type, param);
    copyProgram.bind();
    gl.uniform1i(copyProgram.uniforms.uTexture, target.attach(0));
    blit(newFBO.fbo);
    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 createTextureAsync (url) {
    var 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]));

    var obj = {
        texture: texture,
        width: 1,
        height: 1,
        attach: function attach (id) {
            gl.activeTexture(gl.TEXTURE0 + id);
            gl.bindTexture(gl.TEXTURE_2D, texture);
            return id;
        }
    };

    var image = new Image();
    image.onload = function () {
        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;
}

function updateKeywords () {
    var 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);

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

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

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

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

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

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

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

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

function step (dt) {
    gl.disable(gl.BLEND);
    gl.viewport(0, 0, velocity.width, velocity.height);

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

    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.fbo);
    velocity.swap();

    divergenceProgram.bind();
    gl.uniform2f(divergenceProgram.uniforms.texelSize, velocity.texelSizeX, velocity.texelSizeY);
    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);
    blit(pressure.write.fbo);
    pressure.swap();

    pressureProgram.bind();
    gl.uniform2f(pressureProgram.uniforms.texelSize, velocity.texelSizeX, velocity.texelSizeY);
    gl.uniform1i(pressureProgram.uniforms.uDivergence, divergence.attach(0));
    for (var 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, 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.fbo);
    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); }
    var 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, dye.width, dye.height);

    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.fbo);
    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);
    }

    var width = target == null ? gl.drawingBufferWidth : target.width;
    var height = target == null ? gl.drawingBufferHeight : target.height;
    gl.viewport(0, 0, width, height);

    var fbo = target == null ? null : target.fbo;
    if (!config.TRANSPARENT)
        { drawColor(fbo, normalizeColor(config.BACK_COLOR)); }
    if (target == null && config.TRANSPARENT)
    drawDisplay(fbo, width, height);
}

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



function drawDisplay (fbo, width, 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));
        var 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(fbo);
}

function applyBloom (source, destination) {
    if (bloomFramebuffers.length < 2)
        { return; }

    var last = destination;

    gl.disable(gl.BLEND);
    bloomPrefilterProgram.bind();
    var knee = config.BLOOM_THRESHOLD * config.BLOOM_SOFT_KNEE + 0.0001;
    var curve0 = config.BLOOM_THRESHOLD - knee;
    var curve1 = knee * 2;
    var 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 (var i = 0; i < bloomFramebuffers.length; i++) {
        var dest = bloomFramebuffers[i];
        gl.uniform2f(bloomBlurProgram.uniforms.texelSize, last.texelSizeX, last.texelSizeY);
        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 (var i$1 = bloomFramebuffers.length - 2; i$1 >= 0; i$1--) {
        var baseTex = bloomFramebuffers[i$1];
        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.fbo);
        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);
    gl.viewport(0, 0, destination.width, destination.height);
    blit(destination.fbo);
}

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

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

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

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

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

function multipleSplats (amount) {
    for (var i = 0; i < amount; i++) {
        var color = generateColor();
        color.r *= 10.0;
        color.g *= 10.0;
        color.b *= 10.0;
        var x = Math.random();
        var y = Math.random();
        var dx = 1000 * (Math.random() - 0.5);
        var dy = 1000 * (Math.random() - 0.5);
        splat(x, y, dx, dy, color);
    }
}

function splat (x, y, dx, dy, color) {
    gl.viewport(0, 0, velocity.width, velocity.height);
    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.fbo);
    velocity.swap();

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

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

canvas.addEventListener('mousedown', function (e) {
    var posX = scaleByPixelRatio(e.offsetX);
    var posY = scaleByPixelRatio(e.offsetY);
    var pointer = pointers.find(function (p) { return p.id == -1; });
    if (pointer == null)
        { pointer = new pointerPrototype(); }
    updatePointerDownData(pointer, -1, posX, posY);
});

canvas.addEventListener('mousemove', function (e) {
    var pointer = pointers[0];
    if (!pointer.down) { return; }
    var posX = scaleByPixelRatio(e.offsetX);
    var posY = scaleByPixelRatio(e.offsetY);
    updatePointerMoveData(pointer, posX, posY);
});

window.addEventListener('mouseup', function () {
    updatePointerUpData(pointers[0]);
});

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

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

window.addEventListener('touchend', function (e) {
    var touches = e.changedTouches;
    var loop = function ( i ) {
        var pointer = pointers.find(function (p) { return p.id == touches[i].identifier; });
        if (pointer == null) { return; }
        updatePointerUpData(pointer);
    };

    for (var i = 0; i < touches.length; i++)
    loop( i );
});

window.addEventListener('keydown', function (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 = true;
}

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

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

function generateColor () {
    var 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) {
    var 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: r,
        g: g,
        b: b
    };
}

function normalizeColor (input) {
    var output = {
        r: input.r / 255,
        g: input.g / 255,
        b: input.b / 255
    };
    return output;
}

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

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

    var min = Math.round(resolution);
    var 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 scaleByPixelRatio (input) {
    var pixelRatio = window.devicePixelRatio || 1;
    return Math.floor(input * pixelRatio);
}

function hashCode (s) {
    if (s.length == 0) { return 0; }
    var hash = 0;
    for (var i = 0; i < s.length; i++) {
        hash = (hash << 5) - hash + s.charCodeAt(i);
        hash |= 0; // Convert to 32bit integer
    }
    return hash;
};