threeJS21-geometry-buffergeometry-indexed - 好文

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如有错别字或有理解不到位的地方，可以留言或者加微信15250969798，博主会及时修改！！！！！

博主的案例并不难，只是为了更好的给想入门threeJS的同学一点点经验！！！！！

涉及的知识点博主已经从three源码库里面摘要出来放在对应的注释里面！

前面学习了常见的几种格式的模型加载，只要选择对应的加载器加载，获取对应的geometry和material就基本可以还原模型了！

后面博主会考虑把loader加载的模型格式补全！

今天我们学习geometry类的BufferGeometry，buffergeometry是自由度最高的一种geometry，它可以自定义顶点、颜色、法线等属性！

本案例是根据顶点索引生成三角形再组合成一个面

图示:

代码：
<html> <head> <title>threeJS21-geometry-buffergeometry-indexed</title> <style>
body { background-color: #000; margin: 0px; overflow: hidden; } #WebGL { width:
100%; height: 100%; position: absolute; left: 0; top: 0; z-index: 999; }
</style> </head> <body> <script
src="http://libs.baidu.com/jquery/2.0.0/jquery.js"></script> <script
src="../../../build/three.js"></script> <script
src="../../js/controls/OrbitControls.js"></script> <div id="WebGL"></div>
<script> 'use strict'; var container, camera, scene, renderer, geometry,
material, animate, controls; //常用变量 var spotLight, mshStdBox, mesh; //自定义对象变量
var target = new THREE.Vector3(0, 30, 0); var webGLW = $('#WebGL').width(); var
webGLH = $('#WebGL').height(); init(); animate(); function init() { container =
document.getElementById('WebGL'); scene = new THREE.Scene(); scene.background =
new THREE.Color(0xcfcfcf); scene.fog = new THREE.Fog(0xa0a0a0, 200, 1000); //雾
camera = new THREE.PerspectiveCamera(40, window.innerWidth /
window.innerHeight, 0.1, 1000); camera.position.set(0, 60, -100);
camera.lookAt(target); var ambient = new THREE.AmbientLight(0xffffff);
scene.add(ambient); lights(); //灯光：聚光灯 // lightsHelper(spotLight); //灯光显示助手
plane() //// 地面 loadModel(); //添加模型 rendererScene(); //场景渲染
OrbitControls(camera, renderer);
//OrbitControls控件模块，90版本鼠标右键上下是移动，96版本之后右键上下是缩放
window.addEventListener('resize', onWindowResize, false); //监听屏幕变化 } function
plane() { // 地面 let grid_mesh = new THREE.Mesh(new
THREE.PlaneBufferGeometry(2000, 2000), new THREE.MeshPhongMaterial({ color:
0x999999, depthWrite: false })); grid_mesh.rotation.x = -Math.PI / 2;
grid_mesh.receiveShadow = true; scene.add(grid_mesh); var grid = new
THREE.GridHelper(2000, 20, 0x000000, 0x000000); grid.material.opacity = 0.2;
grid.material.transparent = true; scene.add(grid); } function lights() { //
SpotLight( color：颜色, intensity：强度, distance：发光距离, angle：角度, penumbra：边缘范围,
decay：衰减 ) spotLight = new THREE.SpotLight(0xffffff, 1);
spotLight.position.set(10, 120, -30); spotLight.angle = Math.PI / 4;
spotLight.penumbra = 0.05; //边缘范围，反比 spotLight.decay = 2; //衰减系数，反比
spotLight.distance = 400; //发光距离 spotLight.castShadow = true; //阴影
spotLight.shadow.mapSize.width = 1024; spotLight.shadow.mapSize.height = 1024;
spotLight.shadow.camera.near = 10; //近截面 spotLight.shadow.camera.far = 250;
scene.add(spotLight); } function lightsHelper(lightsObject) { //
聚光灯显示助手SpotLightHelper( light:灯光, color：颜色 ) var lightHelper = new
THREE.SpotLightHelper(lightsObject, 0xdfdfdf); scene.add(lightHelper); var mesh
= new THREE.Mesh(new THREE.PlaneBufferGeometry(200, 200), new
THREE.MeshPhongMaterial({ color: 0x9cfcf99, depthWrite: false }));
mesh.rotation.x = -Math.PI / 2; mesh.position.set(0, -20, 0) mesh.receiveShadow
= true; scene.add(mesh); } function loadModel() { //模型 var geometry = new
THREE.BufferGeometry(); var indices = []; var vertices = []; var normals = [];
var colors = []; var size = 50; var segments = 10; var halfSize = size / 2; var
segmentSize = size / segments; // 为简单网格几何体生成顶点、法线和颜色数据 for (var i = 0; i <=
segments; i++) { var y = (i * segmentSize) - halfSize; for (var j = 0; j <=
segments; j++) { var x = (j * segmentSize) - halfSize; vertices.push(x, -y, 0);
normals.push(0, 0, 1); var r = (x / size) + 0.5; var g = (y / size) + 0.5;
colors.push(r, g, 1); } } // 生成索引（元素数组缓冲区的数据） for (var i = 0; i < segments;
i++) { for (var j = 0; j < segments; j++) { var a = i * (segments + 1) + (j +
1); var b = i * (segments + 1) + j; var c = (i + 1) * (segments + 1) + j; var d
= (i + 1) * (segments + 1) + (j + 1); // 每次迭代生成两个面（三角形） indices.push(a, b, d);
// 第一个面 indices.push(b, c, d); // 第二个面 } } geometry.setIndex(indices); //设置索引
// addAttribute ( name : String, attribute : BufferAttribute )
geometry.addAttribute('position', new THREE.Float32BufferAttribute(vertices,
3)); geometry.addAttribute('normal', new THREE.Float32BufferAttribute(normals,
3)); geometry.addAttribute('color', new THREE.Float32BufferAttribute(colors,
3)); var material = new THREE.MeshPhongMaterial({ specular: 0x111111,
shininess: 250, side: THREE.DoubleSide, vertexColors: THREE.VertexColors });
mesh = new THREE.Mesh(geometry, material); mesh.position.set(0, 30, 0)
scene.add(mesh); } function onWindowResize() { camera.aspect =
window.innerWidth / window.innerHeight; camera.updateProjectionMatrix();
renderer.setSize(window.innerWidth, window.innerHeight); } function
rendererScene() { renderer = new THREE.WebGLRenderer({ antialias: true });
renderer.setPixelRatio(window.devicePixelRatio);
renderer.setSize(window.innerWidth, window.innerHeight);
renderer.shadowMap.enabled = true; renderer.shadowMap.type =
THREE.PCFSoftShadowMap; renderer.gammaInput = true; renderer.gammaOutput =
true; container.appendChild(renderer.domElement); } function
OrbitControls(camera, renderer) { //OrbitControls控件操作模块 controls = new
THREE.OrbitControls(camera, renderer.domElement); controls.target = target;
//控制的target controls.autoRotate = true; //是否自动旋转 controls.autoRotateSpeed =
0.5; //自动旋转速度，正比 } function animate() { requestAnimationFrame(animate); if
(controls) controls.update(); renderer.render(scene, camera); }; </script>
</body> </html>

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