Three.js 雪花教程-拓冰建站

雪花 ·Snow· ▶ 在线运行案例

案例合集：三维可视化功能案例（threehub.cn）
开源仓库github地址：https://github.com/z2586300277/three-cesium-examples
400个案例代码:网盘链接

你将学到什么

onBeforeCompile 注入 GLSL 改造内置材质
OrbitControls 相机轨道交互
BufferGeometry 自定义顶点/索引数据
监听窗口resize同步更新 camera 与 renderer

效果说明

本案例演示雪花效果：基于 WebGL 实现「雪花」可视化效果，附完整可运行源码；核心用到 onBeforeCompile、OrbitControls、BufferGeometry。建议先打开文首在线案例查看动态画面，再对照下方源码逐步理解。

核心概念

Scene / Camera / WebGLRenderer构成最小渲染闭环；大场景可开logarithmicDepthBuffer缓解 Z-fighting。
onBeforeCompile在 Three 拼好内置 shader 后替换#include片段，适合在 PBR 材质上叠加大屏特效。
OrbitControls提供轨道旋转/缩放；开启enableDamping后需在 animate 中controls.update()。

实现步骤

搭建 Scene、PerspectiveCamera、WebGLRenderer，挂载 canvas 并处理resize
定义 uniforms / onBeforeCompile 或 ShaderMaterial，编写 GLSL 与材质参数
创建 OrbitControls（及 Raycaster 等交互控件，若源码包含）
在requestAnimationFrame循环中更新状态并 render（Cesium 为viewer.render或自动渲染）

代码要点

import * as THREE from "three";import { OrbitControls } from "three/addons/controls/OrbitControls.js";
let scene = new THREE.Scene(); let camera = new THREE.PerspectiveCamera(45, innerWidth / innerHeight, 0.1, 1000); camera.position.set(0, 0, 7); let renderer = new THREE.WebGLRenderer(); renderer.setSize(innerWidth, innerHeight); document.body.appendChild(renderer.domElement); window.addEventListener("resize", event => { camera.aspect = innerWidth / innerHeight; camera.updateProjectionMatrix(); renderer.setSize(innerWidth, innerHeight); })
new OrbitControls(camera, renderer.domElement);
let gu = { time: {value: 0} }
class Flakes extends THREE.Points{ constructor(gu){ let flakeData = []; let g = new THREE.BufferGeometry().setFromPoints(new Array(1000).fill().map(_ => { flakeData.push(((Math.random() < 0.5) ? -1 : 1), 0, 0, 0); return new THREE.Vector3().random().subScalar(0.5).multiplyScalar(10) })); g.setAttribute("flakeData", new THREE.Float32BufferAttribute(flakeData, 4)); let m = new THREE.PointsMaterial({ color: 0xfbec5d, size: 0.75, onBeforeCompile: shader => { shader.uniforms.time = gu.time; shader.vertexShader =uniform float time; attribute vec4 flakeData; varying vec4 vFlakeData; varying float vId; ${shader.vertexShader}.replace(#include,#include vId = float(gl_VertexID); vFlakeData = flakeData;
vec3 p = vec3(position);
transformed.y = 5. - mod(p.y + time * 0.5 - 5., 10.););shader.fragmentShader =uniform float time; varying vec4 vFlakeData; varying float vId;
// 2D Random float random (in vec2 st) { return fract(sin(dot(st.xy, vec2(12.9898,78.233)))
43758.5453123);
}// 2D Noise based on Morgan McGuire @morgan3d // https://www.shadertoy.com/view/4dS3Wd float noise (in vec2 st) { vec2 i = floor(st); vec2 f = fract(st);
// Four corners in 2D of a tile float a = random(i); float b = random(i + vec2(1.0, 0.0)); float c = random(i + vec2(0.0, 1.0)); float d = random(i + vec2(1.0, 1.0));
// Smooth Interpolation
// Cubic Hermine Curve. Same as SmoothStep() vec2 u = ff(3.0-2.0*f); // u = smoothstep(0.,1.,f);
// Mix 4 coorners percentages return mix(a, b, u.x) + (c - a)u.y(1.0 - u.x) + (d - b)u.xu.y; }
mat2 rot(float a){ float c = cos(a); float s = sin(a); return mat2(c, -s, s, c); }${shader.fragmentShader}.replace(#include,#include vec2 baseUv = gl_PointCoord.xy - 0.5; vec2 uv = rot(mod(vId + (timevFlakeData.x), PI2))(baseUv * 10.); float a = atan(uv.y, uv.x) + PI; float r = length(uv); float aStep = PI / 3.; float aPart = abs(mod(a, aStep) - (0.5 * aStep)); vec2 suv = vec2(cos(aPart), sin(aPart)) * r - vec2(time, 0.); float n = noise(suv + vId); //n = pow(n, 2.); if (length(baseUv) > 0.5 || n < 0.5) discard;).replace(#include,#include diffuseColor.rgb = mix(diffuseColor.rgb, vec3(0.875, 0, 0), smoothstep(1., 0.5, n));); console.log(shader.fragmentShader); } }) super(g, m); } } let flakes = new Flakes(gu); scene.add(flakes);
let clock = new THREE.Clock();
renderer.setAnimationLoop(() => { gu.time.value = clock.getElapsedTime() * 0.5; renderer.render(scene, camera); });