three.js example
Original code from this post, by prisoner849, as featured in this collection.
<div id="three_container"></div>
<script type="module">
import * as THREE from "/scripts/threejs/three.js"
import { OrbitControls } from "/scripts/threejs/OrbitControls.js"
const noise = `// Simplex 4D Noise
// by Ian McEwan, Ashima Arts
//
vec4 permute(vec4 x){return mod(((x*34.0)+1.0)*x, 289.0);}
float permute(float x){return floor(mod(((x*34.0)+1.0)*x, 289.0));}
vec4 taylorInvSqrt(vec4 r){return 1.79284291400159 - 0.85373472095314 * r;}
float taylorInvSqrt(float r){return 1.79284291400159 - 0.85373472095314 * r;}
vec4 grad4(float j, vec4 ip){
const vec4 ones = vec4(1.0, 1.0, 1.0, -1.0);
vec4 p,s;
p.xyz = floor( fract (vec3(j) * ip.xyz) * 7.0) * ip.z - 1.0;
p.w = 1.5 - dot(abs(p.xyz), ones.xyz);
s = vec4(lessThan(p, vec4(0.0)));
p.xyz = p.xyz + (s.xyz*2.0 - 1.0) * s.www;
return p;
}
float snoise(vec4 v){
const vec2 C = vec2( 0.138196601125010504, // (5 - sqrt(5))/20 G4
0.309016994374947451); // (sqrt(5) - 1)/4 F4
// First corner
vec4 i = floor(v + dot(v, C.yyyy) );
vec4 x0 = v - i + dot(i, C.xxxx);
// Other corners
// Rank sorting originally contributed by Bill Licea-Kane, AMD (formerly ATI)
vec4 i0;
vec3 isX = step( x0.yzw, x0.xxx );
vec3 isYZ = step( x0.zww, x0.yyz );
// i0.x = dot( isX, vec3( 1.0 ) );
i0.x = isX.x + isX.y + isX.z;
i0.yzw = 1.0 - isX;
// i0.y += dot( isYZ.xy, vec2( 1.0 ) );
i0.y += isYZ.x + isYZ.y;
i0.zw += 1.0 - isYZ.xy;
i0.z += isYZ.z;
i0.w += 1.0 - isYZ.z;
// i0 now contains the unique values 0,1,2,3 in each channel
vec4 i3 = clamp( i0, 0.0, 1.0 );
vec4 i2 = clamp( i0-1.0, 0.0, 1.0 );
vec4 i1 = clamp( i0-2.0, 0.0, 1.0 );
// x0 = x0 - 0.0 + 0.0 * C
vec4 x1 = x0 - i1 + 1.0 * C.xxxx;
vec4 x2 = x0 - i2 + 2.0 * C.xxxx;
vec4 x3 = x0 - i3 + 3.0 * C.xxxx;
vec4 x4 = x0 - 1.0 + 4.0 * C.xxxx;
// Permutations
i = mod(i, 289.0);
float j0 = permute( permute( permute( permute(i.w) + i.z) + i.y) + i.x);
vec4 j1 = permute( permute( permute( permute (
i.w + vec4(i1.w, i2.w, i3.w, 1.0 ))
+ i.z + vec4(i1.z, i2.z, i3.z, 1.0 ))
+ i.y + vec4(i1.y, i2.y, i3.y, 1.0 ))
+ i.x + vec4(i1.x, i2.x, i3.x, 1.0 ));
// Gradients
// ( 7*7*6 points uniformly over a cube, mapped onto a 4-octahedron.)
// 7*7*6 = 294, which is close to the ring size 17*17 = 289.
vec4 ip = vec4(1.0/294.0, 1.0/49.0, 1.0/7.0, 0.0) ;
vec4 p0 = grad4(j0, ip);
vec4 p1 = grad4(j1.x, ip);
vec4 p2 = grad4(j1.y, ip);
vec4 p3 = grad4(j1.z, ip);
vec4 p4 = grad4(j1.w, ip);
// Normalise gradients
vec4 norm = taylorInvSqrt(vec4(dot(p0,p0), dot(p1,p1), dot(p2, p2), dot(p3,p3)));
p0 *= norm.x;
p1 *= norm.y;
p2 *= norm.z;
p3 *= norm.w;
p4 *= taylorInvSqrt(dot(p4,p4));
// Mix contributions from the five corners
vec3 m0 = max(0.6 - vec3(dot(x0,x0), dot(x1,x1), dot(x2,x2)), 0.0);
vec2 m1 = max(0.6 - vec2(dot(x3,x3), dot(x4,x4) ), 0.0);
m0 = m0 * m0;
m1 = m1 * m1;
return 49.0 * ( dot(m0*m0, vec3( dot( p0, x0 ), dot( p1, x1 ), dot( p2, x2 )))
+ dot(m1*m1, vec2( dot( p3, x3 ), dot( p4, x4 ) ) ) ) ;
}`;
class Particles extends THREE.Points {
constructor(gu) {
let particlePos = []; //vec4 (speed, shift radius, phase, reserved);
let particleAlpha = []; //vec4 (phase, speed, reserved, reserved)
let g = new THREE.BufferGeometry().setFromPoints(
new Array(1000).fill().map((_) => {
particlePos.push(Math.random() * 0.2 + 0.2, Math.random() + 1, Math.random(), 0);
particleAlpha.push(Math.random(), Math.random() * 0.4 + 0.1, 0, 0);
let r = 5;
return new THREE.Vector3().setFromCylindricalCoords(
Math.sqrt(r * r * Math.random()),
Math.random() * Math.PI * 2,
Math.random() * 10
);
})
).setAttribute("particlePos", new THREE.Float32BufferAttribute(particlePos, 4))
.setAttribute("particleAlpha", new THREE.Float32BufferAttribute(particleAlpha, 4));
let m = new THREE.PointsMaterial({
size: 0.5,
color: "turquoise",
transparent: true,
depthTest: false,
onBeforeCompile: (shader) => {
shader.uniforms.time = gu.time;
shader.uniforms.heightLimMin = { value: 0 };
shader.uniforms.heightLimMax = { value: 10 };
shader.vertexShader = `
uniform float time;
uniform float heightLimMin;
uniform float heightLimMax;
attribute vec4 particlePos;
attribute vec4 particleAlpha;
varying float vParticleAlpha;
mat2 rot(float a){float c = cos(a); float s = sin(a); return mat2(c, s, -s, c);}
${noise}
${shader.vertexShader}
`.replace(
`#include <begin_vertex>`,
`#include <begin_vertex>
float t = time;
vParticleAlpha = sin(mod((particleAlpha.x + t * particleAlpha.y) * PI2, PI2)) * 0.5 + 0.5;
float hGap = heightLimMax - heightLimMin;
float halfGap = hGap * 0.5;
float verticalSpeed = particlePos.x;
float verticalShift = mod((position.y - heightLimMin) + verticalSpeed * t, hGap);
transformed.y = heightLimMin + verticalShift; // make it looped on Y-axis
float verticalFade = smoothstep(halfGap, halfGap - 1., abs(verticalShift - halfGap)); // for both top and bottom
vParticleAlpha *= verticalFade;
// particle shift
float n = snoise(vec4(position, t * 0.05));
float radius = particlePos.y;
float phase = particlePos.z;
float angle = (phase + n) * PI ;
vec2 shiftVec = rot(angle) * vec2(radius, 0.);
transformed.xz += shiftVec; // make it shifting
`
).replace(
`gl_PointSize = size;`,
`gl_PointSize = size * vParticleAlpha;`
);
//console.log(shader.vertexShader);
shader.fragmentShader = `
varying float vParticleAlpha;
${shader.fragmentShader}
`.replace(
`#include <color_fragment>`,
`#include <color_fragment>
vec2 uv = gl_PointCoord.xy - 0.5;
float d = sqrt(dot(uv, uv));
if(d > 0.5) discard;
float f = smoothstep(0.5, 0., d);
f *= f * f * f * f;
f = f * 0.95 + 0.05;
diffuseColor.a = vParticleAlpha * f;
`
);
//console.log(shader.fragmentShader);
}
});
super(g, m);
}
}
const div = document.getElementById (`three_container`)
div.width = div.parentNode.scrollWidth
div.height = div.width * 9 / 16
let scene = new THREE.Scene()
scene.background = new THREE.Color ("hotpink")
let camera = new THREE.PerspectiveCamera (60, 16 / 9, 1, 1000)
camera.position.set (0, 5, 10)
let renderer = new THREE.WebGLRenderer ({ antialias: true })
renderer.setSize (div.width, div.height)
div.appendChild (renderer.domElement)
let controls = new OrbitControls (camera, renderer.domElement)
controls.enableDamping = true
controls.target.set (0, 5, 0)
let gu = {
time: { value: 0 }
}
let grid = new THREE.GridHelper ()
scene.add (grid)
let particles = new Particles (gu)
scene.add (particles)
renderer.setAnimationLoop(t => {
gu.time.value = t / 1000
controls.update ()
renderer.render (scene, camera)
});
</script>