阅读背景:

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

来源:互联网 

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.PointCloudthree.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

<!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>

分享到: