Three.js 实现模型材质局部辉光（发光，光晕）效果和解决辉光影响场景背景图显示的问题

1.Three.js 实现模型材质局部辉光（发光，光晕）效果

2.解决辉光效果影响场景背景图显示的问题

相关API的使用：

1. EffectComposer（渲染后处理的通用框架，用于将多个渲染通道（pass）组合在一起创建特定的视觉效果）

2. RenderPass(是用于渲染场景的通道。它将场景和相机作为输入，使用Three.js默认的渲染器（renderer）来进行场景渲染，并将结果输出给下一个渲染通道)

3. UnrealBloomPass(是 three.js 中用于实现泛光效果的后期处理效果，通过高斯模糊和屏幕混合技术，将亮度较高的区域扩散开来，从而实现逼真的泛光效果。)

4. ShaderPass（是一个自定义着色器的通道。它允许你指定自定义的着色器代码，并将其应用于场景的渲染结果。这样你可以创建各种各样的图形效果，如高斯模糊、后处理效果等）

在上一篇 Three.js加载外部glb,fbx,gltf,obj 模型文件 的文章基础上新增一个 createEffectComposer（效果合成器方法）和sceneAnimation（效果器渲染方法）以及getFlowMeaterList(获取需要辉光效果材质的方法)

首先引入相关的api

import { EffectComposer } from 'three/examples/jsm/postprocessing/EffectComposer.js'
import { RenderPass } from 'three/examples/jsm/postprocessing/RenderPass.js'
import { UnrealBloomPass} from 'three/examples/jsm/postprocessing/OutlinePass.js'
import { ShaderPass } from 'three/examples/jsm/postprocessing/ShaderPass.js'

创建效果合成器方法（createEffectComposer）:需要创建两个合成器 effectComposer 用于正常渲染场景，glowComposer用于渲染辉光效果

createEffectComposer() {const { clientHeight, clientWidth } = this.container// 场景渲染器this.effectComposer = new EffectComposer(this.renderer)const renderPass = new RenderPass(this.scene, this.camera)this.effectComposer.addPass(renderPass)//创建辉光效果this.unrealBloomPass = new UnrealBloomPass(new THREE.Vector2(clientWidth, clientHeight), 0, 0, 0)this.unrealBloomPass.threshold = 1 // 辉光强度this.unrealBloomPass.strength = 0 // 辉光阈值this.unrealBloomPass.radius = 1 //辉光半径this.unrealBloomPass.renderToScreen = false // // 辉光合成器this.glowComposer = new EffectComposer(this.renderer)this.glowComposer.renderToScreen = falsethis.glowComposer.addPass(new RenderPass(this.scene, this.camera))this.glowComposer.addPass(this.unrealBloomPass)// 着色器let shaderPass = new ShaderPass(new THREE.ShaderMaterial({uniforms: {baseTexture: { value: null },bloomTexture: { value: this.glowComposer.renderTarget2.texture },tDiffuse: {value: null}},vertexShader:'\t\t\tvarying vec2 vUv;\n' +'\n' +'\t\t\tvoid main() {\n' +'\n' +'\t\t\t\tvUv = uv;\n' +'\n' +'\t\t\t\tgl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );\n' +'\n' +'\t\t\t}',fragmentShader:'\t\t\tuniform sampler2D baseTexture;\n' +'\t\t\tuniform sampler2D bloomTexture;\n' +'\n' +'\t\t\tvarying vec2 vUv;\n' +'\n' +'\t\t\tvoid main() {\n' +'\n' +'\t\t\t\tgl_FragColor = ( texture2D( baseTexture, vUv ) + vec4( 1.0 ) * texture2D( bloomTexture, vUv ) );\n' +'\n' +'\t\t\t}',defines: {}}), 'baseTexture')shaderPass.renderToScreen = trueshaderPass.needsSwap = truethis.effectComposer.addPass(shaderPass)}

获取需要辉光渲染的材质：

   getFlowMeaterList(){const modelMaterialList= []this.model.traverse((v) => {if (v.isMesh && v.material) {const { name, color,map } = v.material// 统一将模型材质 设置为 MeshLambertMaterial 类型v.material = new THREE.MeshLambertMaterial({map,transparent: true,color,name,})modelMaterialList.push(v)	}})this.glowMaterialList = modelMaterialList.map(v=>v.name)}

渲染场景方法（sceneAnimation）:处理不需要辉光的材质。注意：辉光效果会影响场景背景图的正常显示需要单独处理（这里通过 instanceof THREE.Scene 判断是否是场景材质然后进行单独处理）

   sceneAnimation() {this.renderAnimation = requestAnimationFrame(() => this.sceneAnimation())this.controls.update()// 将不需要处理辉光的材质进行存储备份this.scene.traverse((v) => {// 备份一份场景背景然后清空if (v instanceof THREE.Scene) {this.materials.scene = v.backgroundv.background = null}if (!this.glowMaterialList.includes(v.name) && v.isMesh) {// 备份当前材质内容this.materials[v.uuid] = v.material// 将不需要辉光的材质设置为黑色v.material = new THREE.MeshBasicMaterial({ color: 'black' })}})// 执行辉光效果器渲染this.glowComposer.render()// 在辉光渲染器执行完之后在恢复材质原效果this.scene.traverse((v) => {if (this.materials[v.uuid]) {v.material = this.materials[v.uuid]delete this.materials[v.uuid]}if (v instanceof THREE.Scene) {v.background = this.materials.scenedelete this.materials.scene}})// 执行场景效果器渲染this.effectComposer.render()}