08.webgl_buffergeometry_attributes_none ，three官方示例+编辑器+AI快速学习

本实例主要讲解内容

这个Three.js示例展示了无属性几何体渲染技术，通过WebGL 2的gl_VertexID特性和伪随机数生成算法，在着色器中动态计算顶点位置和颜色，而不需要在CPU端预先定义几何体数据。

核心技术包括：

WebGL 2的顶点ID特性
着色器中的伪随机数生成
无属性几何体渲染
纯GPU端的几何体生成

在这里插入图片描述

完整代码注释

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<html lang="en"><head><title>three.js WebGL 2 - buffergeometry - attributes - none</title><meta charset="utf-8"><meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0"><link type="text/css" rel="stylesheet" href="main.css"></head><body><div id="info"><a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> WebGL 2 - buffergeometry - attributes - none</div><!-- 顶点着色器 --><script id="vertexShader" type="x-shader/x-vertex">uniform mat4 modelViewMatrix;uniform mat4 projectionMatrix;uniform float seed; // 随机数种子// IEEE 754浮点数常量const uint ieeeMantissa = 0x007FFFFFu;const uint ieeeOne = 0x3F800000u;// 哈希函数 - 生成伪随机无符号整数uint hash(uint x) {x += ( x << 10u );x ^= ( x >>  6u );x += ( x <<  3u );x ^= ( x >> 11u );x += ( x << 15u );return x;}// 二维哈希函数uint hash(uvec2 v) { return hash( v.x ^ hash(v.y) ); }// 生成0-1之间的伪随机浮点数float hashNoise(vec2 xy) {uint m = hash(floatBitsToUint(xy));m &= ieeeMantissa;m |= ieeeOne;return uintBitsToFloat( m ) - 1.0;}// 生成指定范围内的伪随机浮点数float pseudoRandom(float lower, float delta, in vec2 xy) {return lower + delta*hashNoise(xy);}// 生成指定范围内的伪随机三维向量vec3 pseudoRandomVec3(float lower, float upper, int index) {float delta = upper - lower;float x = pseudoRandom(lower, delta, vec2(index, 0));float y = pseudoRandom(lower, delta, vec2(index, 1));float z = pseudoRandom(lower, delta, vec2(index, 2));return vec3(x, y, z);}out vec3 vColor; // 输出到片段着色器的颜色void main()	{// 计算顶点位置// 使用 gl_VertexID 作为索引生成伪随机位置// 每个三角形的三个顶点共享相同的基础位置，添加微小偏移形成三角形const float scale = 1.0/64.0;vec3 position = pseudoRandomVec3(-1.0, +1.0, gl_VertexID/3) + scale * pseudoRandomVec3(-1.0, +1.0, gl_VertexID);// 计算顶点颜色vec3 color = pseudoRandomVec3(0.25, 1.0, gl_VertexID/3);// 设置顶点位置和颜色gl_Position = projectionMatrix * modelViewMatrix * vec4(position, 1.0 );vColor = color;}</script><!-- 片段着色器 --><script id="fragmentShader" type="x-shader/x-fragment">precision mediump float;in vec3 vColor; // 从顶点着色器传入的颜色out vec4 fColor; // 最终输出颜色void main()	{fColor = vec4(vColor, 1); // 使用传入的颜色作为片段颜色}</script><script type="importmap">{"imports": {"three": "../build/three.module.js","three/addons/": "./jsm/"}}</script><script type="module">import * as THREE from 'three';let camera, scene, renderer, mesh;init();function init() {// 初始化相机camera = new THREE.PerspectiveCamera( 27, window.innerWidth / window.innerHeight, 1, 3500 );camera.position.z = 4;// 初始化场景scene = new THREE.Scene();scene.background = new THREE.Color( 0x050505 );scene.fog = new THREE.Fog( 0x050505, 2000, 3500 );// 创建几何体// 注意：这里没有设置任何顶点属性，所有数据都在着色器中生成const triangleCount = 10000;const vertexCountPerTriangle = 3;const vertexCount = triangleCount * vertexCountPerTriangle;const geometry = new THREE.BufferGeometry();geometry.setDrawRange( 0, vertexCount ); // 仅设置绘制范围// 创建材质const material = new THREE.RawShaderMaterial( {uniforms: {seed: { value: 42 }, // 设置随机数种子},vertexShader: document.getElementById( 'vertexShader' ).textContent,fragmentShader: document.getElementById( 'fragmentShader' ).textContent,side: THREE.DoubleSide, // 双面渲染glslVersion: THREE.GLSL3 // 使用GLSL 3.0} );// 创建网格mesh = new THREE.Mesh( geometry, material );mesh.frustumCulled = false; // 禁用视锥体剔除scene.add( mesh );// 初始化渲染器renderer = new THREE.WebGLRenderer( { antialias: true } );renderer.setPixelRatio( window.devicePixelRatio );renderer.setSize( window.innerWidth, window.innerHeight );renderer.setAnimationLoop( animate );document.body.appendChild( renderer.domElement );}// 动画循环function animate( time ) {// 旋转网格mesh.rotation.x = time / 1000.0 * 0.25;mesh.rotation.y = time / 1000.0 * 0.50;renderer.render( scene, camera );}</script></body>
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