WebGL в холст p5.js искажается

Question

Я относительно новичок в шейдерах, и у меня проблемы с размещением кода шейдера в канве p5.js. Сценарий smoke.js отлично работает, когда я добавляю его в холст HTML, но когда я пытаюсь поместить его в холст, созданный в p5, он появляется только в верхнем правом углу. Любая идея, что здесь происходит?

см. Верхний правый угол, где находится шейдер.

//smoke.js
//taken from https://codepen.io/PavelDoGreat/details/zdWzEL/

'use strict';

window.addEventListener('load', function () {
    const canvas = document.getElementById('myCanvas');

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

    let config = {
        TEXTURE_DOWNSAMPLE: 1,
        DENSITY_DISSIPATION: 0.98,
        VELOCITY_DISSIPATION: 0.99,
        PRESSURE_DISSIPATION: 0.8,
        PRESSURE_ITERATIONS: 25,
        CURL: 30,
        SPLAT_RADIUS: 0.005
    }

    let pointers = [];
    let splatStack = [];

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

        let gl = canvas.getContext('webgl2', params);
        const isWebGL2 = !!gl;
        if (!isWebGL2)
            gl = canvas.getContext('webgl', params) || canvas.getContext('experimental-webgl', params);

        let halfFloat;
        let supportLinearFiltering;
        if (isWebGL2) {
            gl.getExtension('EXT_color_buffer_float');
            supportLinearFiltering = gl.getExtension('OES_texture_float_linear');
        } else {
            halfFloat = gl.getExtension('OES_texture_half_float');
            supportLinearFiltering = gl.getExtension('OES_texture_half_float_linear');
        }

        gl.clearColor(0.0, 0.0, 0.0, 1.0);

        const halfFloatTexType = isWebGL2 ? gl.HALF_FLOAT : halfFloat.HALF_FLOAT_OES;
        let formatRGBA;
        let formatRG;
        let formatR;

        if (isWebGL2) {
            formatRGBA = getSupportedFormat(gl, gl.RGBA16F, gl.RGBA, halfFloatTexType);
            formatRG = getSupportedFormat(gl, gl.RG16F, gl.RG, halfFloatTexType);
            formatR = getSupportedFormat(gl, gl.R16F, gl.RED, halfFloatTexType);
        }
        else {
            formatRGBA = getSupportedFormat(gl, gl.RGBA, gl.RGBA, halfFloatTexType);
            formatRG = getSupportedFormat(gl, gl.RGBA, gl.RGBA, halfFloatTexType);
            formatR = getSupportedFormat(gl, gl.RGBA, gl.RGBA, halfFloatTexType);
        }

        return {
            gl,
            ext: {
                formatRGBA,
                formatRG,
                formatR,
                halfFloatTexType,
                supportLinearFiltering
            }
        };
    }

    function getSupportedFormat(gl, internalFormat, format, type) {
        if (!supportRenderTextureFormat(gl, internalFormat, format, type)) {
            switch (internalFormat) {
                case gl.R16F:
                    return getSupportedFormat(gl, gl.RG16F, gl.RG, type);
                case gl.RG16F:
                    return getSupportedFormat(gl, gl.RGBA16F, gl.RGBA, type);
                default:
                    return null;
            }
        }

        return {
            internalFormat,
            format
        }
    }

    function supportRenderTextureFormat(gl, internalFormat, format, type) {
        let texture = gl.createTexture();
        gl.bindTexture(gl.TEXTURE_2D, texture);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
        gl.texImage2D(gl.TEXTURE_2D, 0, internalFormat, 4, 4, 0, format, type, null);

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

        const status = gl.checkFramebufferStatus(gl.FRAMEBUFFER);
        if (status != gl.FRAMEBUFFER_COMPLETE)
            return false;
        return true;
    }

    function pointerPrototype() {
        this.id = -1;
        this.x = 0;
        this.y = 0;
        this.dx = 0;
        this.dy = 0;
        this.down = false;
        this.moved = false;
        this.color = [30, 0, 300];
    }

    pointers.push(new pointerPrototype());

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

            gl.attachShader(this.program, vertexShader);
            gl.attachShader(this.program, fragmentShader);
            gl.linkProgram(this.program);

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

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

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

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

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

        return shader;
    };

    const baseVertexShader = compileShader(gl.VERTEX_SHADER, `
    precision highp float;
    precision mediump sampler2D;

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

    void main () {
        vUv = aPosition * 0.5 + 0.5;
        vL = vUv - vec2(texelSize.x, 0.0);
        vR = vUv + vec2(texelSize.x, 0.0);
        vT = vUv + vec2(0.0, texelSize.y);
        vB = vUv - vec2(0.0, texelSize.y);
        gl_Position = vec4(aPosition, 0.0, 1.0);
    }
`);

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

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

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

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

    varying vec2 vUv;
    uniform sampler2D uTexture;

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

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

    varying vec2 vUv;
    uniform sampler2D uTarget;
    uniform float aspectRatio;
    uniform vec3 color;
    uniform vec2 point;
    uniform float radius;

    void main () {
        vec2 p = vUv - point.xy;
        p.x *= aspectRatio;
        vec3 splat = exp(-dot(p, p) / radius) * color;
        vec3 base = texture2D(uTarget, vUv).xyz;
        gl_FragColor = vec4(base + splat, 1.0);
    }
`);

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

    varying vec2 vUv;
    uniform sampler2D uVelocity;
    uniform sampler2D uSource;
    uniform vec2 texelSize;
    uniform float dt;
    uniform float dissipation;

    vec4 bilerp (in sampler2D sam, in vec2 p) {
        vec4 st;
        st.xy = floor(p - 0.5) + 0.5;
        st.zw = st.xy + 1.0;
        vec4 uv = st * texelSize.xyxy;
        vec4 a = texture2D(sam, uv.xy);
        vec4 b = texture2D(sam, uv.zy);
        vec4 c = texture2D(sam, uv.xw);
        vec4 d = texture2D(sam, uv.zw);
        vec2 f = p - st.xy;
        return mix(mix(a, b, f.x), mix(c, d, f.x), f.y);
    }

    void main () {
        vec2 coord = gl_FragCoord.xy - dt * texture2D(uVelocity, vUv).xy;
        gl_FragColor = dissipation * bilerp(uSource, coord);
        gl_FragColor.a = 1.0;
    }
`);

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

    varying vec2 vUv;
    uniform sampler2D uVelocity;
    uniform sampler2D uSource;
    uniform vec2 texelSize;
    uniform float dt;
    uniform float dissipation;

    void main () {
        vec2 coord = vUv - dt * texture2D(uVelocity, vUv).xy * texelSize;
        gl_FragColor = dissipation * texture2D(uSource, coord);
        gl_FragColor.a = 1.0;
    }
`);

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

    varying vec2 vUv;
    varying vec2 vL;
    varying vec2 vR;
    varying vec2 vT;
    varying vec2 vB;
    uniform sampler2D uVelocity;

    vec2 sampleVelocity (in vec2 uv) {
        vec2 multiplier = vec2(1.0, 1.0);
        if (uv.x < 0.0) { uv.x = 0.0; multiplier.x = -1.0; }
        if (uv.x > 1.0) { uv.x = 1.0; multiplier.x = -1.0; }
        if (uv.y < 0.0) { uv.y = 0.0; multiplier.y = -1.0; }
        if (uv.y > 1.0) { uv.y = 1.0; multiplier.y = -1.0; }
        return multiplier * texture2D(uVelocity, uv).xy;
    }

    void main () {
        float L = sampleVelocity(vL).x;
        float R = sampleVelocity(vR).x;
        float T = sampleVelocity(vT).y;
        float B = sampleVelocity(vB).y;
        float div = 0.5 * (R - L + T - B);
        gl_FragColor = vec4(div, 0.0, 0.0, 1.0);
    }
`);

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

    varying vec2 vUv;
    varying vec2 vL;
    varying vec2 vR;
    varying vec2 vT;
    varying vec2 vB;
    uniform sampler2D uVelocity;

    void main () {
        float L = texture2D(uVelocity, vL).y;
        float R = texture2D(uVelocity, vR).y;
        float T = texture2D(uVelocity, vT).x;
        float B = texture2D(uVelocity, vB).x;
        float vorticity = R - L - T + B;
        gl_FragColor = vec4(vorticity, 0.0, 0.0, 1.0);
    }
`);

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

    varying vec2 vUv;
    varying vec2 vT;
    varying vec2 vB;
    uniform sampler2D uVelocity;
    uniform sampler2D uCurl;
    uniform float curl;
    uniform float dt;

    void main () {
        float T = texture2D(uCurl, vT).x;
        float B = texture2D(uCurl, vB).x;
        float C = texture2D(uCurl, vUv).x;
        vec2 force = vec2(abs(T) - abs(B), 0.0);
        force *= 1.0 / length(force + 0.00001) * curl * C;
        vec2 vel = texture2D(uVelocity, vUv).xy;
        gl_FragColor = vec4(vel + force * dt, 0.0, 1.0);
    }
`);

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

    varying vec2 vUv;
    varying vec2 vL;
    varying vec2 vR;
    varying vec2 vT;
    varying vec2 vB;
    uniform sampler2D uPressure;
    uniform sampler2D uDivergence;

    vec2 boundary (in vec2 uv) {
        uv = min(max(uv, 0.0), 1.0);
        return uv;
    }

    void main () {
        float L = texture2D(uPressure, boundary(vL)).x;
        float R = texture2D(uPressure, boundary(vR)).x;
        float T = texture2D(uPressure, boundary(vT)).x;
        float B = texture2D(uPressure, boundary(vB)).x;
        float C = texture2D(uPressure, vUv).x;
        float divergence = texture2D(uDivergence, vUv).x;
        float pressure = (L + R + B + T - divergence) * 0.25;
        gl_FragColor = vec4(pressure, 0.0, 0.0, 1.0);
    }
`);

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

    varying vec2 vUv;
    varying vec2 vL;
    varying vec2 vR;
    varying vec2 vT;
    varying vec2 vB;
    uniform sampler2D uPressure;
    uniform sampler2D uVelocity;

    vec2 boundary (in vec2 uv) {
        uv = min(max(uv, 0.0), 1.0);
        return uv;
    }

    void main () {
        float L = texture2D(uPressure, boundary(vL)).x;
        float R = texture2D(uPressure, boundary(vR)).x;
        float T = texture2D(uPressure, boundary(vT)).x;
        float B = texture2D(uPressure, boundary(vB)).x;
        vec2 velocity = texture2D(uVelocity, vUv).xy;
        velocity.xy -= vec2(R - L, T - B);
        gl_FragColor = vec4(velocity, 0.0, 1.0);
    }
`);

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

    uniform vec2 u_resolution;
    uniform vec2 u_mouse;
    uniform float u_time;

    float circle(in vec2 _st, in float _radius){
        vec2 dist = _st-vec2(0.5);
	    return 1.-smoothstep(_radius-(_radius*0.01),
                         _radius+(_radius*0.01),
                         dot(dist,dist)*4.0);
    }

    void main(){
	    vec2 st = gl_FragCoord.xy/u_resolution.xy;

	    vec3 color = vec3(circle(st,0.9));

	    gl_FragColor = vec4( color, 1.0 );
    }
`);

    let textureWidth;
    let textureHeight;
    let density;
    let velocity;
    let divergence;
    let curl;
    let pressure;
    initFramebuffers();

    const clearProgram = new GLProgram(baseVertexShader, clearShader);
    const displayProgram = new GLProgram(baseVertexShader, displayShader);
    const splatProgram = new GLProgram(baseVertexShader, splatShader);
    const advectionProgram = new GLProgram(baseVertexShader, ext.supportLinearFiltering ? advectionShader : advectionManualFilteringShader);
    const divergenceProgram = new GLProgram(baseVertexShader, divergenceShader);
    const curlProgram = new GLProgram(baseVertexShader, curlShader);
    const vorticityProgram = new GLProgram(baseVertexShader, vorticityShader);
    const pressureProgram = new GLProgram(baseVertexShader, pressureShader);
    const gradienSubtractProgram = new GLProgram(baseVertexShader, gradientSubtractShader);
    const circProgram = new GLProgram(baseVertexShader, circShader);

    function initFramebuffers() {
        // textureWidth = gl.drawingBufferWidth >> config.TEXTURE_DOWNSAMPLE;
        // textureHeight = gl.drawingBufferHeight >> config.TEXTURE_DOWNSAMPLE;
        textureWidth = canvas.width;
        textureHeight = canvas.height;

        const texType = ext.halfFloatTexType;
        const rgba = ext.formatRGBA;
        const rg = ext.formatRG;
        const r = ext.formatR;

        density = createDoubleFBO(2, textureWidth, textureHeight, rgba.internalFormat, rgba.format, texType, ext.supportLinearFiltering ? gl.LINEAR : gl.NEAREST);
        velocity = createDoubleFBO(0, textureWidth, textureHeight, rg.internalFormat, rg.format, texType, ext.supportLinearFiltering ? gl.LINEAR : gl.NEAREST);
        divergence = createFBO(4, textureWidth, textureHeight, r.internalFormat, r.format, texType, gl.NEAREST);
        curl = createFBO(5, textureWidth, textureHeight, r.internalFormat, r.format, texType, gl.NEAREST);
        pressure = createDoubleFBO(6, textureWidth, textureHeight, r.internalFormat, r.format, texType, gl.NEAREST);
    }

    function createFBO(texId, w, h, internalFormat, format, type, param) {
        gl.activeTexture(gl.TEXTURE0 + texId);
        let texture = gl.createTexture();
        gl.bindTexture(gl.TEXTURE_2D, texture);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, param);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, param);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
        gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
        gl.texImage2D(gl.TEXTURE_2D, 0, internalFormat, w, h, 0, format, type, null);

        let fbo = gl.createFramebuffer();
        gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
        gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, 0);
        // gl.viewport(0, 0, w, h);
        gl.viewport(0, 0, canvas.width, canvas.height);

        gl.clear(gl.COLOR_BUFFER_BIT);

        return [texture, fbo, texId];
    }

    function createDoubleFBO(texId, w, h, internalFormat, format, type, param) {
        let fbo1 = createFBO(texId, w, h, internalFormat, format, type, param);
        let fbo2 = createFBO(texId + 1, w, h, internalFormat, format, type, param);

        return {
            get read() {
                return fbo1;
            },
            get write() {
                return fbo2;
            },
            swap() {
                let temp = fbo1;
                fbo1 = fbo2;
                fbo2 = temp;
            }
        }
    }

    const blit = (() => {
        gl.bindBuffer(gl.ARRAY_BUFFER, gl.createBuffer());
        gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([-1, -1, -1, 1, 1, 1, 1, -1]), gl.STATIC_DRAW);
        gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, gl.createBuffer());
        gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array([0, 1, 2, 0, 2, 3]), gl.STATIC_DRAW);
        gl.vertexAttribPointer(0, 2, gl.FLOAT, false, 0, 0);
        gl.enableVertexAttribArray(0);

        return (destination) => {
            gl.bindFramebuffer(gl.FRAMEBUFFER, destination);
            gl.drawElements(gl.TRIANGLES, 6, gl.UNSIGNED_SHORT, 0);
        }
    })();

    let lastTime = Date.now();
    multipleSplats(parseInt(Math.random() * 20) + 5);
    update();

    function update() {
        // resizeCanvas();
        // webglUtils.resizeCanvasToDisplaySize(canvas);

        const dt = Math.min((Date.now() - lastTime) / 1000, 0.016);
        lastTime = Date.now();

        gl.viewport(0, 0, canvas.width, canvas.height);
        // gl.viewport(0, 0, canvas.clientWidth, canvas.clientHeight);
        circProgram.bind();


        if (splatStack.length > 0)
            multipleSplats(splatStack.pop());

        advectionProgram.bind();
        gl.uniform2f(advectionProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight);
        gl.uniform1i(advectionProgram.uniforms.uVelocity, velocity.read[2]);
        gl.uniform1i(advectionProgram.uniforms.uSource, velocity.read[2]);
        gl.uniform1f(advectionProgram.uniforms.dt, dt);
        gl.uniform1f(advectionProgram.uniforms.dissipation, config.VELOCITY_DISSIPATION);
        blit(velocity.write[1]);
        velocity.swap();

        gl.uniform1i(advectionProgram.uniforms.uVelocity, velocity.read[2]);
        gl.uniform1i(advectionProgram.uniforms.uSource, density.read[2]);
        gl.uniform1f(advectionProgram.uniforms.dissipation, config.DENSITY_DISSIPATION);
        blit(density.write[1]);
        density.swap();


        for (var i = 0; i < pointers.length; i++) {
            const pointer = pointers[i];
            if (pointer.moved) {
                splat(pointer.x, pointer.y, pointer.dx, pointer.dy, pointer.color);
                pointer.moved = false;
            }
        }

        curlProgram.bind();
        gl.uniform2f(curlProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight);
        gl.uniform1i(curlProgram.uniforms.uVelocity, velocity.read[2]);
        blit(curl[1]);

        vorticityProgram.bind();
        gl.uniform2f(vorticityProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight);
        gl.uniform1i(vorticityProgram.uniforms.uVelocity, velocity.read[2]);
        gl.uniform1i(vorticityProgram.uniforms.uCurl, curl[2]);
        gl.uniform1f(vorticityProgram.uniforms.curl, config.CURL);
        gl.uniform1f(vorticityProgram.uniforms.dt, dt);
        blit(velocity.write[1]);
        velocity.swap();

        divergenceProgram.bind();
        gl.uniform2f(divergenceProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight);
        gl.uniform1i(divergenceProgram.uniforms.uVelocity, velocity.read[2]);
        blit(divergence[1]);

        clearProgram.bind();
        let pressureTexId = pressure.read[2];
        gl.activeTexture(gl.TEXTURE0 + pressureTexId);
        gl.bindTexture(gl.TEXTURE_2D, pressure.read[0]);
        gl.uniform1i(clearProgram.uniforms.uTexture, pressureTexId);
        gl.uniform1f(clearProgram.uniforms.value, config.PRESSURE_DISSIPATION);
        blit(pressure.write[1]);
        pressure.swap();

        pressureProgram.bind();
        gl.uniform2f(pressureProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight);
        gl.uniform1i(pressureProgram.uniforms.uDivergence, divergence[2]);
        pressureTexId = pressure.read[2];
        gl.uniform1i(pressureProgram.uniforms.uPressure, pressureTexId);
        gl.activeTexture(gl.TEXTURE0 + pressureTexId);
        for (let i = 0; i < config.PRESSURE_ITERATIONS; i++) {
            gl.bindTexture(gl.TEXTURE_2D, pressure.read[0]);
            blit(pressure.write[1]);
            pressure.swap();
        }

        gradienSubtractProgram.bind();
        gl.uniform2f(gradienSubtractProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight);
        gl.uniform1i(gradienSubtractProgram.uniforms.uPressure, pressure.read[2]);
        gl.uniform1i(gradienSubtractProgram.uniforms.uVelocity, velocity.read[2]);
        blit(velocity.write[1]);
        velocity.swap();


        gl.viewport(0, 0, canvas.width, canvas.height);
        displayProgram.bind();
        gl.uniform1i(displayProgram.uniforms.uTexture, density.read[2]);
        blit(null);



        requestAnimationFrame(update);
    }

    function splat(x, y, dx, dy, color) {
        splatProgram.bind();
        gl.uniform1i(splatProgram.uniforms.uTarget, velocity.read[2]);
        gl.uniform1f(splatProgram.uniforms.aspectRatio, canvas.width / canvas.height);
        gl.uniform2f(splatProgram.uniforms.point, x / canvas.width, 1.0 - y / canvas.height);
        gl.uniform3f(splatProgram.uniforms.color, dx, -dy, 1.0);
        gl.uniform1f(splatProgram.uniforms.radius, config.SPLAT_RADIUS);
        blit(velocity.write[1]);
        velocity.swap();

        gl.uniform1i(splatProgram.uniforms.uTarget, density.read[2]);
        gl.uniform3f(splatProgram.uniforms.color, color[0] * 0.3, color[1] * 0.3, color[2] * 0.3);
        blit(density.write[1]);
        density.swap();
    }

    function multipleSplats(amount) {
        for (let i = 0; i < amount; i++) {
            const color = [Math.random() * 10, Math.random() * 10, Math.random() * 10];
            const x = canvas.width * Math.random();
            const y = canvas.height * Math.random();
            const dx = 1000 * (Math.random() - 0.5);
            const dy = 1000 * (Math.random() - 0.5);
            splat(x, y, dx, dy, color);
        }
    }

    function resizeCanvas() {
        if (canvas.width != canvas.clientWidth || canvas.height != canvas.clientHeight) {
            canvas.width = canvas.clientWidth;
            canvas.height = canvas.clientHeight;
            // canvas.width = document.getElementById("myCanvas").width;
            // canvas.height = document.getElementById("myCanvas").height;

            initFramebuffers();

        }
        // console.log(canvas.width, canvas.height);
        // console.log("client height: ", canvas.clientWidth, canvas.clientHeight);


    }

    canvas.addEventListener('mousemove', (e) => {
        pointers[0].moved = pointers[0].down;
        pointers[0].dx = (e.offsetX - pointers[0].x) * 10.0;
        pointers[0].dy = (e.offsetY - pointers[0].y) * 10.0;
        pointers[0].x = e.offsetX;
        pointers[0].y = e.offsetY;
    });

    canvas.addEventListener('touchmove', (e) => {
        e.preventDefault();
        const touches = e.targetTouches;
        for (let i = 0; i < touches.length; i++) {
            let pointer = pointers[i];
            pointer.moved = pointer.down;
            pointer.dx = (touches[i].pageX - pointer.x) * 10.0;
            pointer.dy = (touches[i].pageY - pointer.y) * 10.0;
            pointer.x = touches[i].pageX;
            pointer.y = touches[i].pageY;
        }
    }, false);

    canvas.addEventListener('mousedown', () => {
        pointers[0].down = true;
        pointers[0].color = [Math.random() + 0.2, Math.random() + 0.2, Math.random() + 0.2];
    });

    canvas.addEventListener('touchstart', (e) => {
        e.preventDefault();
        const touches = e.targetTouches;
        for (let i = 0; i < touches.length; i++) {
            if (i >= pointers.length)
                pointers.push(new pointerPrototype());

            pointers[i].id = touches[i].identifier;
            pointers[i].down = true;
            pointers[i].x = touches[i].pageX;
            pointers[i].y = touches[i].pageY;
            pointers[i].color = [Math.random() + 0.2, Math.random() + 0.2, Math.random() + 0.2];
        }
    });

    window.addEventListener('mouseup', () => {
        pointers[0].down = false;
    });

    window.addEventListener('touchend', (e) => {
        const touches = e.changedTouches;
        for (let i = 0; i < touches.length; i++)
            for (let j = 0; j < pointers.length; j++)
                if (touches[i].identifier == pointers[j].id)
                    pointers[j].down = false;
    });

})

<!DOCTYPE html>
<html>

<head>
    <title>Fluid Sim</title>

    <style type="text/css">
        html,
        body {
            overflow: hidden;
        }

        body {
            margin: 0;
            position: absolute;
            width: 100%;
            height: 100%;
        }

        canvas {
            width: 100%;
            height: 100%;
        }
    </style>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/0.9.0/p5.min.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/0.9.0/addons/p5.dom.js"></script>
    <!-- <script id="text/javascript" src="circle.js"></script> -->




</head>

<body>
    <div id="container"></div>
</body>
<script id="text/javascript">
    function setup() {
        let cnv = createCanvas(window.innerWidth, window.innerHeight, WEBGL);
        cnv.id("myCanvas");
        noStroke();
        // cnv.position(0, 0);
        // document.getElementById('container').appendChild(cnv.canvas);
    }



    function draw() {

        background(127);

        push();
        translate(-width / 2, -height / 2, 0)

        fill(255);
        ellipse(windowWidth / 2, windowHeight / 2, 100, 100);
        pop();
    }

    function windowResized() {
        resizeCanvas(windowWidth, windowHeight);
    }

</script>

<script id="text/javascript" src="smoke.js"></script>


</html>