'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
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;
});-->