粒子星空 ·Starry Sky· ▶ 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
- ShaderMaterial 自定义着色器实现核心视觉效果
- OrbitControls 相机轨道交互
requestAnimationFrame渲染循环与resize自适应
效果说明
本案例演示粒子星空效果：基于 WebGL 实现「粒子星空」可视化效果，附完整可运行源码；核心用到 ShaderMaterial、OrbitControls。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。 - ShaderMaterial通过
uniforms+ 自定义 GLSL 控制逐像素/逐点效果；透明粒子常配合depthTest: false。 - 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/examples/jsm/controls/OrbitControls.js'
const box = document.getElementById('box')
const scene = new THREE.Scene()
const camera = new THREE.PerspectiveCamera(75, box.clientWidth / box.clientHeight, 0.1, 1000)
camera.position.set(0, 0, 0.6)
const renderer = new THREE.WebGLRenderer({ antialias: true, alpha: true, logarithmicDepthBuffer: true })
renderer.setSize(box.clientWidth, box.clientHeight)
box.appendChild(renderer.domElement)
const controls = new OrbitControls(camera, renderer.domElement)
controls.enableDamping = true
window.onresize = () => {
renderer.setSize(box.clientWidth, box.clientHeight)
camera.aspect = box.clientWidth / box.clientHeight
camera.updateProjectionMatrix()
}
const uniforms = {
iTime: {
value: 0
},
iResolution: {
value: new THREE.Vector2(box.clientWidth, box.clientHeight)
}
}
const geometry = new THREE.PlaneGeometry(1, 1)
const material = new THREE.ShaderMaterial({
uniforms,
transparent: true,
side: THREE.DoubleSide,
vertexShader:
varying vec3 vPosition; varying vec2 vUv; void main() { vUv = uv; vec4 mvPosition = modelViewMatrix * vec4(position, 1.0); gl_Position = projectionMatrix * mvPosition; }, fragmentShader:uniform float iTime; uniform vec2 iResolution; varying vec2 vUv;#define PASS_COUNT 1 vec4 iMouse = vec4(.0, 0, 0.2, 0); float fBrightness = 2.5;
// Number of angular segments float fSteps = 121.0;
float fParticleSize = 0.015; float fParticleLength = 0.5 / 60.0;
// Min and Max star position radius. Min must be present to prevent stars too near camera float fMinDist = 0.8; float fMaxDist = 5.0;
float fRepeatMin = 1.0; float fRepeatMax = 2.0;
// fog density float fDepthFade = 0.8;
float Random(float x) { return fract(sin(x123.456)23.4567 + sin(x345.678)45.6789 + sin(x456.789)56.789); }
vec3 GetParticleColour( const in vec3 vParticlePos, const in float fParticleSize, const in vec3 vRayDir ) { vec2 vNormDir = normalize(vRayDir.xy); float d1 = dot(vParticlePos.xy, vNormDir.xy) / length(vRayDir.xy); vec3 vClosest2d = vRayDir * d1;
vec3 vClampedPos = vParticlePos;
vClampedPos.z = clamp(vClosest2d.z, vParticlePos.z - fParticleLength, vParticlePos.z + fParticleLength);
float d = dot(vClampedPos, vRayDir);
vec3 vClosestPos = vRayDir * d;
vec3 vDeltaPos = vClampedPos - vClosestPos; float fClosestDist = length(vDeltaPos) / fParticleSize;
float fShade = clamp(1.0 - fClosestDist, 0.0, 1.0); fShade = fShadeexp2(-dfDepthFade) * fBrightness;
return vec3(fShade); }
vec3 GetParticlePos( const in vec3 vRayDir, const in float fZPos, const in float fSeed ) { float fAngle = atan(vRayDir.x, vRayDir.y); float fAngleFraction = fract(fAngle / (3.14 * 2.0));
float fSegment = floor(fAngleFraction * fSteps + fSeed) + 0.5 - fSeed; float fParticleAngle = fSegment / fSteps(3.142.0);
float fSegmentPos = fSegment / fSteps; float fRadius = fMinDist + Random(fSegmentPos + fSeed) * (fMaxDist - fMinDist);
float tunnelZ = vRayDir.z / length(vRayDir.xy / fRadius);
tunnelZ += fZPos;
float fRepeat = fRepeatMin + Random(fSegmentPos + 0.1 + fSeed) * (fRepeatMax - fRepeatMin);
float fParticleZ = (ceil(tunnelZ / fRepeat) - 0.5) * fRepeat - fZPos;
return vec3( sin(fParticleAngle)fRadius, cos(fParticleAngle)fRadius, fParticleZ ); }
vec3 Starfield( const in vec3 vRayDir, const in float fZPos, const in float fSeed ) { vec3 vParticlePos = GetParticlePos(vRayDir, fZPos, fSeed);
return GetParticleColour(vParticlePos, fParticleSize, vRayDir); }
vec3 RotateX( const in vec3 vPos, const in float fAngle ) { float s = sin(fAngle); float c = cos(fAngle);
vec3 vResult = vec3( vPos.x, cvPos.y + svPos.z, -svPos.y + cvPos.z);
return vResult; }
vec3 RotateY( const in vec3 vPos, const in float fAngle ) { float s = sin(fAngle); float c = cos(fAngle);
vec3 vResult = vec3( cvPos.x + svPos.z, vPos.y, -svPos.x + cvPos.z);
return vResult; }
vec3 RotateZ( const in vec3 vPos, const in float fAngle ) { float s = sin(fAngle); float c = cos(fAngle);
vec3 vResult = vec3( cvPos.x + svPos.y, -svPos.x + cvPos.y, vPos.z);
return vResult; }
void mainVR( out vec4 fragColor, in vec2 fragCoord, vec3 vRayOrigin, vec3 vRayDir ) { /* vec2 vScreenUV = fragCoord.xy / iResolution.xy;
vec2 vScreenPos = vScreenUV * 2.0 - 1.0; vScreenPos.x *= iResolution.x / iResolution.y;
vec3 vRayDir = normalize(vec3(vScreenPos, 1.0));
vec3 vEuler = vec3(0.5 + sin(iTime0.2)0.125, 0.5 + sin(iTime0.1)0.125, iTime0.1 + sin(iTime0.3) * 0.5); if(iMouse.z > 0.0) { vEuler.x = -((iMouse.y / iResolution.y) * 2.0 - 1.0); vEuler.y = -((iMouse.x / iResolution.x) * 2.0 - 1.0); vEuler.z = 0.0; } vRayDir = RotateX(vRayDir, vEuler.x); vRayDir = RotateY(vRayDir, vEuler.y); vRayDir = RotateZ(vRayDir, vEuler.z); */ float fShade = 0.0; float a = 0.2; float b = 10.0; float c = 1.0; float fZPos = 5.0 + iTimec + sin(iTimea) * b; float fSpeed = c + abcos(a * iTime);
fParticleLength = 0.25 * fSpeed / 60.0;
float fSeed = 0.0;
vec3 vResult = mix(vec3(0.005, 0.0, 0.01), vec3(0.01, 0.005, 0.0), vRayDir.y * 0.5 + 0.5);
for(int i=0; i
fragColor = vec4(sqrt(vResult),1.0); }
void main(void) { vec2 vScreenUV = (vUv - 0.5) * 10.0;
vec2 vScreenPos = vScreenUV * 2.0 - 1.0; vScreenPos.x *= iResolution.x / iResolution.y;
vec3 vRayDir = normalize(vec3(vScreenPos, 1.0));
vec3 vEuler = vec3(0.5 + sin(iTime0.2)0.125, 0.5 + sin(iTime0.1)0.125, iTime0.1 + sin(iTime0.3) * 0.5); if(iMouse.z > 0.0) { vEuler.x = -((iMouse.y / iResolution.y) * 2.0 - 1.0); vEuler.y = -((iMouse.x / iResolution.x) * 2.0 - 1.0); vEuler.z = 0.0; } vRayDir = RotateX(vRayDir, vEuler.x); vRayDir = RotateY(vRayDir, vEuler.y); vRayDir = RotateZ(vRayDir, vEuler.z);
float fShade = 0.0; float a = 0.2; float b = 10.0; float c = 1.0; float fZPos = 5.0 + iTimec + sin(iTimea) * b; float fSpeed = c + abcos(a * iTime);
fParticleLength = 0.25 * fSpeed / 60.0;
float fSeed = 0.0;
vec3 vResult = mix(vec3(0.005, 0.0, 0.01), vec3(0.01, 0.005, 0.0), vRayDir.y * 0.5 + 0.5);
for(int i=0; i
gl_FragColor = vec4(sqrt(vResult),1.0); }})const mesh = new THREE.Mesh(geometry, material)
scene.add(mesh)
animate()
function animate() {
uniforms.iTime.value += 0.01
requestAnimationFrame(animate)
controls.update()
renderer.render(scene, camera)
}
完整源码：GitHub
小结
- 本文提供粒子星空完整 Three.js 源码与在线 Demo，建议先运行案例再改 uniform/参数做二次实验
- 更多 Three.js 实战案例见 three-cesium-examples 合集 与 GitHub 开源仓库
