Published
Edited
Dec 14, 2021
5 forks
186 stars
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GPU Boids
simulationLoop = {
restart;
let gif;
let width = regl._gl.canvas.width;
let height = regl._gl.canvas.height;
if (saveGIF) gif = new GIF({ width, height });
var gifTick = 0;
var gifDone = false;
let tick = 0;
let frame = regl.frame(() => {
if (!simulate || (saveGIF && gifDone)) return;
offscreenFBO.resize(width, height);
if (simulate) {
[0, 1].forEach(i => {
positionAccumulationFBO[i].use(() =>
regl.clear({ color: [0, 0, 0, 0] })
);
densityVelocityAccumulationFBO[i].use(() =>
regl.clear({ color: [0, 0, 0, 0] })
);
});
configureAccumulation({ count: n, src: stateFBO[0] }, () => {
if (regl.hasExtension("WEBGL_draw_buffers")) {
positionDensityVelocityFBO[0].use(accumulatePositionAndVelocity);
} else {
positionAccumulationFBO[0].use(accumulatePosition);
densityVelocityAccumulationFBO[0].use(accumulateDensityVelocity);
}
});
blit(() => {
if (regl.hasExtension("WEBGL_draw_buffers")) {
blur[blurStencil]([
{
src1: positionAccumulationTexture[0],
src2: densityVelocityAccumulationTexture[0],
dst: positionDensityVelocityFBO[1],
direction: [1, 0]
},
{
src1: positionAccumulationTexture[1],
src2: densityVelocityAccumulationTexture[1],
dst: positionDensityVelocityFBO[0],
direction: [0, 1]
}
]);
} else {
blur[blurStencil]([
{
src1: positionAccumulationTexture[0],
dst: positionAccumulationFBO[1],
direction: [1, 0]
},
{
src1: positionAccumulationTexture[1],
dst: positionAccumulationFBO[0],
direction: [0, 1]
}
/*{
src1: densityVelocityAccumulationTexture[0],
dst: densityVelocityAccumulationFBO[1],
direction: [1, 0]
},
{
src1: densityVelocityAccumulationTexture[1],
dst: densityVelocityAccumulationFBO[0],
direction: [0, 1]
}*/
]);
}
});
stateFBO[1].use(() => {
iterate({
randomness,
alignment,
velocityEnforcement,
separation,
cohesion,
leading,
time: (tick * 1) / 60,
src: stateFBO[0],
dt,
position: positionAccumulationTexture[0],
densityVelocity: densityVelocityAccumulationTexture[0]
});
});
swap(stateFBO);
}
offscreenFBO.use(() => {
regl.clear({ color: [0, 0, 0, 1] });
drawBoids({ src: stateFBO[0], ɑ, count: n });
});
/*regl.clear({ color: [1, 1, 1, 1] });
copy({
src: densityVelocityAccumulationTexture[0],
γ,
offset: 0.9,
scale: -0.01
});*/
copy({ src: offscreenFBO, γ, offset: 0, scale: 1 });
if (saveGIF && tick++ % gifFrameStride === 0) {
console.log("tick!", gifTick);
regl.poll();
gif.addFrame(regl._gl.canvas, { copy: true, delay: 16 });
if (gifTick++ === gifFrames) {
console.log("GIF capture complete. Beginning conversion…");
gif.render();
frame.cancel();
frame = null;
}
}
});
invalidation.then(() => {
frame && frame.cancel();
if (saveGIF) gif.abort();
});
if (saveGIF) gif.on("finished", blob => saveFile(blob, "boids.gif"));
}
iterate = {
let iterate = regl({
frag: `
precision highp float;
varying vec2 uv;
uniform vec2 inverseResolution;
uniform sampler2D src, position, densityVelocity;
uniform float dt;
uniform float turn;
uniform float uRand, uRandomness;
uniform float uCohesion, uSeparation, uAlignment, uVelocityEnforcement, uLeading;
float random(vec2 co) {
return fract(sin(dot(co.xy,vec2(12.9898,78.233))) * 43758.5453);
}
vec4 derivative (vec4 state) {
vec2 xy1 = state.xy + uLeading * dt * state.zw;
// Sample the blurred density and velocity
vec3 densityVelocitym = texture2D(densityVelocity, xy1).xzw;
xy1 = state.xy + dt * 2.0 * uLeading * densityVelocitym.yz / densityVelocitym.x;
vec4 densityVelocity0 = texture2D(densityVelocity, state.xy);
float density0 = densityVelocity0.x;
vec2 avgVelocity = densityVelocity0.zw / max(density0, 1.0);
// Sample neighboring texels to compute the density gradient
float r = 1.0;
float densityE = texture2D(densityVelocity, state.xy + vec2(inverseResolution.x, 0)).x;
float densityW = texture2D(densityVelocity, state.xy + vec2(-inverseResolution.x, 0)).x;
float densityN = texture2D(densityVelocity, state.xy + vec2(0, inverseResolution.y)).x;
float densityS = texture2D(densityVelocity, state.xy + vec2(0, -inverseResolution.y)).x;
vec2 densityGradient = vec2(densityE - densityW, densityN - densityS) / inverseResolution;
vec4 avgPositionValues = texture2D(position, xy1);
float density1 = texture2D(densityVelocity, xy1).x;
// Divide the sum of velocities by the sum of masses to compute a mass-weighted
// local average position
vec2 avgPosition = vec2(
state.x < 0.5 ? avgPositionValues.x : avgPositionValues.z,
state.y < 0.5 ? avgPositionValues.y : avgPositionValues.w
) / max(density1, 1e-8);
// The magic numbers!
float repulsion = (0.2 * 2.0) * uSeparation;
float follow = (2500.0 * 2.0) * uAlignment;
float cohesion = (850000.0 * 2.0) * uCohesion;
float velocityEnforcement = (190.0 * 2.0) * uVelocityEnforcement;
float vmag = length(state.zw);
vec2 turn = 50.0 * normalize(densityGradient.yx) * pow(density0, 1.0) * vec2(-1.0, 1.0);
vec2 randLoc = gl_FragCoord.xy + uRand * 100.0;
vec2 rand = vec2(random(randLoc), random(randLoc + 0.5)) - 0.5;
return vec4(state.zw,
-densityGradient * repulsion
+ (avgVelocity - state.zw) * follow
+ (avgPosition - state.xy) * cohesion / max(0.01, uLeading)
+ state.zw * (5.0 - vmag) * velocityEnforcement
+ 20000.0 * rand * uRandomness
//+ turn
- 1000.0 * length(state.xy - 0.5) * (state.xy - 0.5)
);
}
void main () {
vec4 yn = texture2D(src, uv);
gl_FragColor = yn + dt * derivative(yn);
float velocity = length(gl_FragColor.zw);
const float maxVelocity = 10.0;
if (velocity > maxVelocity) gl_FragColor.zw *= maxVelocity / velocity;
gl_FragColor.xy = fract(gl_FragColor.xy);//, vec2(0), vec2(1));
}`,
uniforms: {
uRandomness: regl.prop("randomness"),
uRand: () => Math.random(),
uCohesion: regl.prop("cohesion"),
uSeparation: regl.prop("separation"),
uVelocityEnforcement: regl.prop("velocityEnforcement"),
uAlignment: regl.prop("alignment"),
uLeading: regl.prop("leading"),
turn: (ctx, props) => Math.sin(props.time * 0.5) * 30.0,
inverseResolution: [1 / gridSize, 1 / gridSize],
src: regl.prop("src"),
position: regl.prop("position"),
densityVelocity: regl.prop("densityVelocity"),
dt: regl.prop("dt")
}
});
return (props) => blit(() => iterate(props));
}
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