Three.js 罗盘教程

罗盘 ·Compass Shader· ▶ 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

本案例演示罗盘效果：基于 WebGL 实现「罗盘」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 ratio;
  float PI = 3.1415926; uniform float iTime; uniform vec2 iResolution; varying vec2 vUv; vec2 rotate(vec2 p, float rad) { mat2 m = mat2(cos(rad), sin(rad), -sin(rad), cos(rad)); return m * p; } vec2 translate(vec2 p, vec2 diff) { return p - diff; } vec2 scale(vec2 p, float r) { return p*r; } float circle(float pre, vec2 p, float r1, float r2, float power) { float leng = length(p); float d = min(abs(leng-r1), abs(leng-r2)); if (r1 < half1.y) ? abs(half1.x-p.x) : length(p-half1); float dx2 = (p.y < half2.y) ? abs(half2.x-p.x) : length(p-half2); float dy1 = (p.x < half1.x) ? abs(half1.y-p.y) : length(p-half1); float dy2 = (p.x < half2.x) ? abs(half2.y-p.y) : length(p-half2); float d = min(min(dx1, dx2), min(dy1, dy2)); float res = power / d; return clamp(pre + res, 0.0, 1.0); } float radiation(float pre, vec2 p, float r1, float r2, int num, float power) { float angle = 2.0*PI/float(num); float d = 1e10; for(int i=0; i<360; i++) { if (i>=num) break; float _d = (r1 iTime/1.0)0.02+1.1); { vec2 q = p; q = rotate(q, iTime * PI / 6.0); dst = circle(dst, q, 0.85, 0.9, 0.006); dst = radiation(dst, q, 0.87, 0.88, 36, 0.0008); } { vec2 q = p; q = rotate(q, iTime * PI / 6.0); const int n = 6; float angle = PI / float(n); q = rotate(q, floor(atan(q.x, q.y)/angle + 0.5) * angle); for(int i=0; i iTime/1.0)0.04+1.1); q = rotate(q, -iTime * PI / 6.0); for(float i=0.0; i<6.0; i++) { float r = 0.13-i*0.01; q = translate(q, vec2(0.1, 0.0)); dst = circle(dst, q, r, r, 0.002); q = translate(q, -vec2(0.1, 0.0)); q = rotate(q, -iTime * PI / 12.0); } dst = circle(dst, q, 0.04, 0.04, 0.004); } return pow(dst, 2.5) * vec3(1.0, 0.95, 0.8); } void main() { vec2 uv = (vUv - 0.5) * 2.0; gl_FragColor = vec4(calc(uv), 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

  • 本文提供罗盘完整 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