53 Three.js 使用THREE.PointCloud（新版本改名：THREE.Points）批量管理粒子

时间：2021-11-19 05:34:49

简介

当我们如果大量使用粒子时，会很快遇到性能问题，因为每添加一个粒子就是一个模型，因为每个粒子对象分别由THREE.js进行管理，所以，three.js提供了另一种方式来处理大量粒子，那就是使用THREE.PointCloud。通过THREE.PointCloud，three.js不再需要管理大量的单个THREE.Sprite对象，而只需管理THREE.PointCloud实例即可。

实现案例

        //创建THREE.PointCloud粒子的容器
var geometry = new THREE.Geometry();
//创建THREE.PointCloud纹理
var material = new THREE.PointCloudMaterial({size:4, vertexColors:true, color:0xffffff});

//循环将粒子的颜色和位置添加到网格当中
for (var x = -5; x <= 5; x++) {
for (var y = -5; y <= 5; y++) {
var particle = new THREE.Vector3(x * 10, y * 10, 0);
                geometry.vertices.push(particle);
                geometry.colors.push(new THREE.Color(+randomColor()));
            }
        }

//实例化THREE.PointCloud
var cloud = new THREE.PointCloud(geometry, material);
        scene.add(cloud);

在上面的代码当中，我们为添加到THREE.PointCloud中的每一个粒子指定了一个位置和颜色，最后生成的也是五颜六色的粒子。

案例代码

53 Three.js 使用THREE.PointCloud（新版本改名：THREE.Points）批量管理粒子

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style type="text/css">
html, body {
margin: 0;
height: 100%;
}

canvas {
display: block;
}

</style>
</head>
<body onload="draw();">
</body>
<script src="https://johnson2heng.github.io/three.js-demo/lib/three.js"></script>
<script src="https://johnson2heng.github.io/three.js-demo/lib/js/controls/OrbitControls.js"></script>
<script src="https://johnson2heng.github.io/three.js-demo/lib/js/libs/stats.min.js"></script>
<script src="https://johnson2heng.github.io/three.js-demo/lib/js/libs/dat.gui.min.js"></script>
<script>
var renderer;

function initRender() {
 renderer = new THREE.WebGLRenderer({antialias: true});
//renderer.setClearColor(new THREE.Color(0xEEEEEE, 1.0)); //设置背景颜色
 renderer.setSize(window.innerWidth, window.innerHeight);
 document.body.appendChild(renderer.domElement);
 }

var camera;

function initCamera() {
 camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 1, 10000);
 camera.position.set(0, 0, 200);
 }

var scene;

function initScene() {
 scene = new THREE.Scene();
 }

var light;

function initLight() {
 scene.add(new THREE.AmbientLight(0x404040));

 light = new THREE.DirectionalLight(0xffffff);
 light.position.set(1, 1, 1);
 scene.add(light);
 }

function initModel() {

//轴辅助 （每一个轴的长度）
var object = new THREE.AxesHelper(500);
 scene.add(object);

//创建THREE.PointCloud粒子的容器
var geometry = new THREE.Geometry();
//创建THREE.PointCloud纹理
var material = new THREE.PointCloudMaterial({size:4, vertexColors:true, color:0xffffff});

//循环将粒子的颜色和位置添加到网格当中
for (var x = -5; x <= 5; x++) {
for (var y = -5; y <= 5; y++) {
var particle = new THREE.Vector3(x * 10, y * 10, 0);
 geometry.vertices.push(particle);
 geometry.colors.push(new THREE.Color(+randomColor()));
 }
 }

//实例化THREE.PointCloud
var cloud = new THREE.PointCloud(geometry, material);
 scene.add(cloud);

 }

//随机生成颜色
function randomColor() {
var arrHex = ["0","1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d","e","f"],
 strHex = "0x",
 index;
for(var i = 0; i < 6; i++) {
 index = Math.round(Math.random() * 15);
 strHex += arrHex[index];
 }
return strHex;
 }

//初始化性能插件
var stats;

function initStats() {
 stats = new Stats();
 document.body.appendChild(stats.dom);
 }

//用户交互插件 鼠标左键按住旋转，右键按住平移，滚轮缩放
var controls;

function initControls() {

 controls = new THREE.OrbitControls(camera, renderer.domElement);

// 如果使用animate方法时，将此函数删除
//controls.addEventListener( 'change', render );
// 使动画循环使用时阻尼或自转 意思是否有惯性
 controls.enableDamping = true;
//动态阻尼系数 就是鼠标拖拽旋转灵敏度
//controls.dampingFactor = 0.25;
//是否可以缩放
 controls.enableZoom = true;
//是否自动旋转
 controls.autoRotate = false;
//设置相机距离原点的最远距离
 controls.minDistance = 20;
//设置相机距离原点的最远距离
 controls.maxDistance = 10000;
//是否开启右键拖拽
 controls.enablePan = true;
 }

//生成gui设置配置项
var gui;
function initGui() {
//声明一个保存需求修改的相关数据的对象
 gui = {

 };
var datGui = new dat.GUI();
//将设置属性添加到gui当中，gui.add(对象，属性，最小值，最大值）
 }

function render() {
 renderer.render(scene, camera);
 }

//窗口变动触发的函数
function onWindowResize() {
 camera.aspect = window.innerWidth / window.innerHeight;
 camera.updateProjectionMatrix();
 render();
 renderer.setSize(window.innerWidth, window.innerHeight);

 }

function animate() {
//更新控制器
 controls.update();
 render();

//更新性能插件
 stats.update();
 requestAnimationFrame(animate);
 }

function draw() {
 initRender();
 initScene();
 initCamera();
 initLight();
 initModel();
 initControls();
 initStats();
 initGui();

 animate();
 window.onresize = onWindowResize;
 }
</script>
</html>
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