流体模拟
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'use strict'; const canvas = document.getElementsByTagName('canvas')[0]; canvas.width = canvas.clientWidth; canvas.height = canvas.clientHeight; 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); } gl.clearColor(0.0, 0.0, 0.0, 1.0); const halfFloat = gl.getExtension('OES_texture_half_float'); let support_linear_float = gl.getExtension('OES_texture_half_float_linear'); if (isWebGL2) { gl.getExtension('EXT_color_buffer_float'); support_linear_float = gl.getExtension('OES_texture_float_linear'); } const TEXTURE_DOWNSAMPLE = 1; const DENSITY_DISSIPATION = 0.98; const VELOCITY_DISSIPATION = 0.99; const SPLAT_RADIUS = 0.005; const CURL = 30; const PRESSURE_ITERATIONS = 25; 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 displayShader = 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 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); } `); 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 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).y; float R = texture2D(uCurl, vR).y; 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), abs(R) - abs(L)); 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 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); } })(); function clear (target) { gl.bindFramebuffer(gl.FRAMEBUFFER, target); gl.clear(gl.COLOR_BUFFER_BIT); } function createFBO (texId, w, h, internalFormat, format, type, param) { gl.activeTexture(gl.TEXTURE0 + texId); let texture = gl.createTexture(); gl.bindTexture(gl.TEXTURE_2D, texture); gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, param); gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, param); gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE); gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE); gl.texImage2D(gl.TEXTURE_2D, 0, internalFormat, w, h, 0, format, type, null); let fbo = gl.createFramebuffer(); gl.bindFramebuffer(gl.FRAMEBUFFER, fbo); gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, 0); gl.viewport(0, 0, w, h); gl.clear(gl.COLOR_BUFFER_BIT); return [texture, fbo, texId]; } function createDoubleFBO (texId, w, h, internalFormat, format, type, param) { let fbo1 = createFBO(texId , w, h, internalFormat, format, type, param); let fbo2 = createFBO(texId + 1, w, h, internalFormat, format, type, param); return { get first () { return fbo1; }, get second () { return fbo2; }, swap: () => { let temp = fbo1; fbo1 = fbo2; fbo2 = temp; } } } let textureWidth; let textureHeight; let density; let velocity; let divergence; let curl; let pressure; function initFramebuffers () { textureWidth = gl.drawingBufferWidth >> TEXTURE_DOWNSAMPLE; textureHeight = gl.drawingBufferHeight >> TEXTURE_DOWNSAMPLE; const internalFormat = isWebGL2 ? gl.RGBA16F : gl.RGBA; const internalFormatRG = isWebGL2 ? gl.RG16F : gl.RGBA; const formatRG = isWebGL2 ? gl.RG : gl.RGBA; const texType = isWebGL2 ? gl.HALF_FLOAT : halfFloat.HALF_FLOAT_OES; density = createDoubleFBO(0, textureWidth, textureHeight, internalFormat , gl.RGBA , texType, support_linear_float ? gl.LINEAR : gl.NEAREST); velocity = createDoubleFBO(2, textureWidth, textureHeight, internalFormatRG, formatRG, texType, support_linear_float ? gl.LINEAR : gl.NEAREST); divergence = createFBO (4, textureWidth, textureHeight, internalFormatRG, formatRG, texType, gl.NEAREST); curl = createFBO (5, textureWidth, textureHeight, internalFormatRG, formatRG, texType, gl.NEAREST); pressure = createDoubleFBO(6, textureWidth, textureHeight, internalFormatRG, formatRG, texType, gl.NEAREST); } initFramebuffers(); const displayProgram = new GLProgram(baseVertexShader, displayShader); const splatProgram = new GLProgram(baseVertexShader, splatShader); const advectionProgram = new GLProgram(baseVertexShader, support_linear_float ? advectionShader : advectionManualFilteringShader); const divergenceProgram = new GLProgram(baseVertexShader, divergenceShader); const curlProgram = new GLProgram(baseVertexShader, curlShader); const vorticityProgram = new GLProgram(baseVertexShader, vorticityShader); const pressureProgram = new GLProgram(baseVertexShader, pressureShader); const gradienSubtractProgram = new GLProgram(baseVertexShader, gradientSubtractShader); function pointerPrototype () { this.id = -1; this.x = 0; this.y = 0; this.dx = 0; this.dy = 0; this.down = false; this.moved = false; this.color = [30, 0, 300]; } let pointers = []; pointers.push(new pointerPrototype()); for (let i = 0; i < 10; 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); } let lastTime = Date.now(); Update(); function Update () { resizeCanvas(); const dt = Math.min((Date.now() - lastTime) / 1000, 0.016); lastTime = Date.now(); gl.viewport(0, 0, textureWidth, textureHeight); advectionProgram.bind(); gl.uniform2f(advectionProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight); gl.uniform1i(advectionProgram.uniforms.uVelocity, velocity.first[2]); gl.uniform1i(advectionProgram.uniforms.uSource, velocity.first[2]); gl.uniform1f(advectionProgram.uniforms.dt, dt); gl.uniform1f(advectionProgram.uniforms.dissipation, VELOCITY_DISSIPATION); blit(velocity.second[1]); velocity.swap(); gl.uniform1i(advectionProgram.uniforms.uVelocity, velocity.first[2]); gl.uniform1i(advectionProgram.uniforms.uSource, density.first[2]); gl.uniform1f(advectionProgram.uniforms.dissipation, DENSITY_DISSIPATION); blit(density.second[1]); density.swap(); for (let i = 0; i < pointers.length; i++) { const pointer = pointers[i]; if (pointer.moved) { splat(pointer.x, pointer.y, pointer.dx, pointer.dy, pointer.color); pointer.moved = false; } } curlProgram.bind(); gl.uniform2f(curlProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight); gl.uniform1i(curlProgram.uniforms.uVelocity, velocity.first[2]); blit(curl[1]); vorticityProgram.bind(); gl.uniform2f(vorticityProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight); gl.uniform1i(vorticityProgram.uniforms.uVelocity, velocity.first[2]); gl.uniform1i(vorticityProgram.uniforms.uCurl, curl[2]); gl.uniform1f(vorticityProgram.uniforms.curl, CURL); gl.uniform1f(vorticityProgram.uniforms.dt, dt); blit(velocity.second[1]); velocity.swap(); divergenceProgram.bind(); gl.uniform2f(divergenceProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight); gl.uniform1i(divergenceProgram.uniforms.uVelocity, velocity.first[2]); blit(divergence[1]); clear(pressure.first[1]); pressureProgram.bind(); gl.uniform2f(pressureProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight); gl.uniform1i(pressureProgram.uniforms.uDivergence, divergence[2]); for (let i = 0; i < PRESSURE_ITERATIONS; i++) { gl.uniform1i(pressureProgram.uniforms.uPressure, pressure.first[2]); blit(pressure.second[1]); pressure.swap(); } gradienSubtractProgram.bind(); gl.uniform2f(gradienSubtractProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight); gl.uniform1i(gradienSubtractProgram.uniforms.uPressure, pressure.first[2]); gl.uniform1i(gradienSubtractProgram.uniforms.uVelocity, velocity.first[2]); blit(velocity.second[1]); velocity.swap(); gl.viewport(0, 0, gl.drawingBufferWidth, gl.drawingBufferHeight); displayProgram.bind(); gl.uniform1i(displayProgram.uniforms.uTexture, density.first[2]); blit(null); requestAnimationFrame(Update); } function splat (x, y, dx, dy, color) { splatProgram.bind(); gl.uniform1i(splatProgram.uniforms.uTarget, velocity.first[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, SPLAT_RADIUS); blit(velocity.second[1]); velocity.swap(); gl.uniform1i(splatProgram.uniforms.uTarget, density.first[2]); gl.uniform3f(splatProgram.uniforms.color, color[0] * 0.3, color[1] * 0.3, color[2] * 0.3); blit(density.second[1]); density.swap(); } function resizeCanvas () { if (canvas.width != canvas.clientWidth || canvas.height != canvas.clientHeight) { canvas.width = canvas.clientWidth; canvas.height = canvas.clientHeight; initFramebuffers(); } } canvas.addEventListener('mousemove', (e) => { pointers[0].moved = pointers[0].down; pointers[0].dx = (e.offsetX - pointers[0].x) * 10.0; pointers[0].dy = (e.offsetY - pointers[0].y) * 10.0; pointers[0].x = e.offsetX; pointers[0].y = e.offsetY; }); canvas.addEventListener('touchmove', (e) => { e.preventDefault(); const touches = e.targetTouches; for (let i = 0; i < e.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) => { 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 1'use strict';
2const canvas = document.getElementsByTagName('canvas')[0];
2canvas.width = canvas.clientWidth; canvas.height = canvas.clientHeight;
2const params = { alpha: false, depth: false, stencil: false, antialias: false };
2let gl = canvas.getContext('webgl2', params); const isWebGL2 = !!gl;
2if (!isWebGL2) {
2gl = canvas.getContext('webgl', params) || canvas.getContext('experimental-webgl', params);
2}
2gl.clearColor(0.0, 0.0, 0.0, 1.0);
2const halfFloat = gl.getExtension('OES_texture_half_float');
2let support_linear_float = gl.getExtension('OES_texture_half_float_linear');
2if (isWebGL2) {
2 gl.getExtension('EXT_color_buffer_float');
2support_linear_float = gl.getExtension('OES_texture_float_linear');
2}
2const TEXTURE_DOWNSAMPLE = 1;
2const DENSITY_DISSIPATION = 0.98;
2const VELOCITY_DISSIPATION =
20.99;
2const SPLAT_RADIUS = 0.005;
2const CURL = 30;
2const PRESSURE_ITERATIONS = 25;
2class GLProgram {
2constructor (vertexShader, fragmentShader) {
2this.uniforms = {};
2this.program =
2gl.createProgram();
2gl.attachShader(this.program, vertexShader);
2gl.attachShader(this.program, fragmentShader);
2gl.linkProgram(this.program);
2if (!gl.getProgramParameter(this.program, gl.LINK_STATUS))
2throw gl.getProgramInfoLog(this.program);
2const uniformCount = gl.getProgramParameter(this.program, gl.ACTIVE_UNIFORMS);
2for (let i = 0; i < uniformCount; i++) {
2const uniformName = gl.getActiveUniform(this.program, i).name;
2this.uniforms[uniformName] = gl.getUniformLocation(this.program, uniformName);
2}
2}
2bind () {
2gl.useProgram(this.program);
2}
2}
2function compileShader (type, source) {
2const shader = gl.createShader(type);
2 gl.shaderSource(shader, source);
2gl.compileShader(shader);
2if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS))
2throw
2gl.getShaderInfoLog(shader);
2return shader;
2};
2const baseVertexShader = compileShader(gl.VERTEX_SHADER, `
2precision highp float;
2precision mediump sampler2D;
2attribute vec2 aPosition;
2varying vec2 vUv;
2varying vec2 vL;
2varying vec2 vR;
2varying vec2 vT;
2varying vec2 vB;
2uniform vec2 texelSize;
2void main () {
2vUv = aPosition * 0.5 + 0.5;
2vL = vUv - vec2(texelSize.x, 0.0);
2vR = vUv + vec2(texelSize.x, 0.0);
2vT = vUv + vec2(0.0, texelSize.y);
2vB = vUv - vec2(0.0, texelSize.y);
2gl_Position = vec4(aPosition, 0.0, 1.0);
2}
2`);
2const displayShader = compileShader(gl.FRAGMENT_SHADER, `
2 precision highp float;
2 precision mediump sampler2D;
2 varying vec2 vUv;
2 varying vec2 vL;
2 varying vec2 vR;
2 varying vec2 vT;
2 varying vec2 vB;
2 uniform sampler2D uTexture;
2 void main () {
2 gl_FragColor = texture2D(uTexture, vUv);
2 }
2`);
2const splatShader = compileShader(gl.FRAGMENT_SHADER, `
2 precision highp float;
2 precision mediump sampler2D;
2 varying vec2 vUv;
2 uniform sampler2D uTarget;
2 uniform float aspectRatio;
2 uniform vec3 color;
2 uniform vec2 point;
2 uniform float radius;
2 void main () {
2 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); } `); 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 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).y; float R = texture2D(uCurl, vR).y; 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), abs(R) - abs(L)); 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 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); } })(); function clear (target) { gl.bindFramebuffer(gl.FRAMEBUFFER, target); gl.clear(gl.COLOR_BUFFER_BIT); } function createFBO (texId, w, h, internalFormat, format, type, param) { gl.activeTexture(gl.TEXTURE0 + texId); let texture = gl.createTexture(); gl.bindTexture(gl.TEXTURE_2D, texture); gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, param); gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, param); gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE); gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE); gl.texImage2D(gl.TEXTURE_2D, 0, internalFormat, w, h, 0, format, type, null); let fbo = gl.createFramebuffer(); gl.bindFramebuffer(gl.FRAMEBUFFER, fbo); gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, 0); gl.viewport(0, 0, w, h); gl.clear(gl.COLOR_BUFFER_BIT); return [texture, fbo, texId]; } function createDoubleFBO (texId, w, h, internalFormat, format, type, param) { let fbo1 = createFBO(texId , w, h, internalFormat, format, type, param); let fbo2 = createFBO(texId + 1, w, h, internalFormat, format, type, param); return { get first () { return fbo1; }, get second () { return fbo2; }, swap: () => { let temp = fbo1; fbo1 = fbo2; fbo2 = temp; } } } let textureWidth; let textureHeight; let density; let velocity; let divergence; let curl; let pressure; function initFramebuffers () { textureWidth = gl.drawingBufferWidth >> TEXTURE_DOWNSAMPLE; textureHeight = gl.drawingBufferHeight >> TEXTURE_DOWNSAMPLE; const internalFormat = isWebGL2 ? gl.RGBA16F : gl.RGBA; const internalFormatRG = isWebGL2 ? gl.RG16F : gl.RGBA; const formatRG = isWebGL2 ? gl.RG : gl.RGBA; const texType = isWebGL2 ? gl.HALF_FLOAT : halfFloat.HALF_FLOAT_OES; density = createDoubleFBO(0, textureWidth, textureHeight, internalFormat , gl.RGBA , texType, support_linear_float ? gl.LINEAR : gl.NEAREST); velocity = createDoubleFBO(2, textureWidth, textureHeight, internalFormatRG, formatRG, texType, support_linear_float ? gl.LINEAR : gl.NEAREST); divergence = createFBO (4, textureWidth, textureHeight, internalFormatRG, formatRG, texType, gl.NEAREST); curl = createFBO (5, textureWidth, textureHeight, internalFormatRG, formatRG, texType, gl.NEAREST); pressure = createDoubleFBO(6, textureWidth, textureHeight, internalFormatRG, formatRG, texType, gl.NEAREST); } initFramebuffers(); const displayProgram = new GLProgram(baseVertexShader, displayShader); const splatProgram = new GLProgram(baseVertexShader, splatShader); const advectionProgram = new GLProgram(baseVertexShader, support_linear_float ? advectionShader : advectionManualFilteringShader); const divergenceProgram = new GLProgram(baseVertexShader, divergenceShader); const curlProgram = new GLProgram(baseVertexShader, curlShader); const vorticityProgram = new GLProgram(baseVertexShader, vorticityShader); const pressureProgram = new GLProgram(baseVertexShader, pressureShader); const gradienSubtractProgram = new GLProgram(baseVertexShader, gradientSubtractShader); function pointerPrototype () { this.id = -1; this.x = 0; this.y = 0; this.dx = 0; this.dy = 0; this.down = false; this.moved = false; this.color = [30, 0, 300]; } let pointers = []; pointers.push(new pointerPrototype()); for (let i = 0; i < 10; 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); } let lastTime = Date.now(); Update(); function Update () { resizeCanvas(); const dt = Math.min((Date.now() - lastTime) / 1000, 0.016); lastTime = Date.now(); gl.viewport(0, 0, textureWidth, textureHeight); advectionProgram.bind(); gl.uniform2f(advectionProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight); gl.uniform1i(advectionProgram.uniforms.uVelocity, velocity.first[2]); gl.uniform1i(advectionProgram.uniforms.uSource, velocity.first[2]); gl.uniform1f(advectionProgram.uniforms.dt, dt); gl.uniform1f(advectionProgram.uniforms.dissipation, VELOCITY_DISSIPATION); blit(velocity.second[1]); velocity.swap(); gl.uniform1i(advectionProgram.uniforms.uVelocity, velocity.first[2]); gl.uniform1i(advectionProgram.uniforms.uSource, density.first[2]); gl.uniform1f(advectionProgram.uniforms.dissipation, DENSITY_DISSIPATION); blit(density.second[1]); density.swap(); for (let i = 0; i < pointers.length; i++) { const pointer = pointers[i]; if (pointer.moved) { splat(pointer.x, pointer.y, pointer.dx, pointer.dy, pointer.color); pointer.moved = false; } } curlProgram.bind(); gl.uniform2f(curlProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight); gl.uniform1i(curlProgram.uniforms.uVelocity, velocity.first[2]); blit(curl[1]); vorticityProgram.bind(); gl.uniform2f(vorticityProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight); gl.uniform1i(vorticityProgram.uniforms.uVelocity, velocity.first[2]); gl.uniform1i(vorticityProgram.uniforms.uCurl, curl[2]); gl.uniform1f(vorticityProgram.uniforms.curl, CURL); gl.uniform1f(vorticityProgram.uniforms.dt, dt); blit(velocity.second[1]); velocity.swap(); divergenceProgram.bind(); gl.uniform2f(divergenceProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight); gl.uniform1i(divergenceProgram.uniforms.uVelocity, velocity.first[2]); blit(divergence[1]); clear(pressure.first[1]); pressureProgram.bind(); gl.uniform2f(pressureProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight); gl.uniform1i(pressureProgram.uniforms.uDivergence, divergence[2]); for (let i = 0; i < PRESSURE_ITERATIONS; i++) { gl.uniform1i(pressureProgram.uniforms.uPressure, pressure.first[2]); blit(pressure.second[1]); pressure.swap(); } gradienSubtractProgram.bind(); gl.uniform2f(gradienSubtractProgram.uniforms.texelSize, 1.0 / textureWidth, 1.0 / textureHeight); gl.uniform1i(gradienSubtractProgram.uniforms.uPressure, pressure.first[2]); gl.uniform1i(gradienSubtractProgram.uniforms.uVelocity, velocity.first[2]); blit(velocity.second[1]); velocity.swap(); gl.viewport(0, 0, gl.drawingBufferWidth, gl.drawingBufferHeight); displayProgram.bind(); gl.uniform1i(displayProgram.uniforms.uTexture, density.first[2]); blit(null); requestAnimationFrame(Update); } function splat (x, y, dx, dy, color) { splatProgram.bind(); gl.uniform1i(splatProgram.uniforms.uTarget, velocity.first[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, SPLAT_RADIUS); blit(velocity.second[1]); velocity.swap(); gl.uniform1i(splatProgram.uniforms.uTarget, density.first[2]); gl.uniform3f(splatProgram.uniforms.color, color[0] * 0.3, color[1] * 0.3, color[2] * 0.3); blit(density.second[1]); density.swap(); } function resizeCanvas () { if (canvas.width != canvas.clientWidth || canvas.height != canvas.clientHeight) { canvas.width = canvas.clientWidth; canvas.height = canvas.clientHeight; initFramebuffers(); } } canvas.addEventListener('mousemove', (e) => { pointers[0].moved = pointers[0].down; pointers[0].dx = (e.offsetX - pointers[0].x) * 10.0; pointers[0].dy = (e.offsetY - pointers[0].y) * 10.0; pointers[0].x = e.offsetX; pointers[0].y = e.offsetY; }); canvas.addEventListener('touchmove', (e) => { e.preventDefault(); const touches = e.targetTouches; for (let i = 0; i < e.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) => { 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; });-->

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