今天我们来用ThreeJS的库实现一个波纹粒子效果，我们用到的ThreeJS的库有CanvasRenderer.js，OrbitControls.js，Projector.js，stats.min.js和three.js。这些库都是不可或缺的，我们先来看看实现的效果，如下图所示。
我们再来看看项目结构是怎么样的，项目结构如下图所示。
我们的效果全部写在了index.html里，现在我们直接贴出index.html的代码，同学们可以直接拿来运行，代码如下。
<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <title>演示页面</title> <script src="three.js"></script> <script src="Projector.js"></script> <script src="CanvasRenderer.js"></script> <script src="stats.min.js"></script> <script src="OrbitControls.js"></script></head><body></body><script> var SEPARATION = 200, AMOUNTX = 60, AMOUNTY = 60; var container, stats; var camera, scene, renderer, controls; var particles, particle, count = 0; var windowHalfX = window.innerWidth / 2; var windowHalfY = window.innerHeight / 2; var raycaster = new THREE.Raycaster(); var mouse = new THREE.Vector2(); function init() { container = document.createElement(‘div‘); document.body.appendChild(container); camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 1, 10000); scene = new THREE.Scene(); /** * 设置光源 * */ //点光源 var point = new THREE.PointLight(0xffffff);//白光 point.position.set(1200, 1200, 1200);//点光源位置 scene.add(point);//点光源添加进场景 //环境光 var ambient = new THREE.AmbientLight(0x999999);//白光 scene.add(ambient);//环境光添加进场景 //模型 var cubeGeometry = new THREE.CubeGeometry(1000, 1000, 1000); var cubeMaterial = new THREE.MeshLambertMaterial({ color:0xffff00 //side:THREE.DoubleSide });//材质对象 var cubeMesh = new THREE.Mesh(cubeGeometry, cubeMaterial);//网格模型对象 cubeMesh.translateY(500); scene.add(cubeMesh);//正方体网格模型添加到场景中 //粒子 particles = new Array(); var PI2 = Math.PI * 2; var material = new THREE.SpriteCanvasMaterial({ color: 0xffffff, program: function(context) { context.beginPath(); context.arc(0, 0, 0.5, 0, PI2, true); context.fill(); } }); var i = 0; for (var ix = 0; ix < AMOUNTX; ix++) { for (var iy = 0; iy < AMOUNTY; iy++) { particle = particles[i++] = new THREE.Sprite(material); particle.position.x = ix * SEPARATION - ((AMOUNTX * SEPARATION) / 2); particle.position.z = iy * SEPARATION - ((AMOUNTY * SEPARATION) / 2); scene.add(particle); } } /** * 创建渲染器对象 * */ renderer = new THREE.CanvasRenderer(); renderer.setPixelRatio(window.devicePixelRatio); renderer.setSize(window.innerWidth, window.innerHeight); container.appendChild(renderer.domElement); window.addEventListener(‘resize‘, onWindowResize, false); //交互控制器 /** * 鼠标键盘事件监听器 * */ controls = new THREE.OrbitControls(camera, renderer.domElement); controls.enableDamping = true; controls.dampingFactor = 0.1; controls.screenSpacePanning = true; controls.minDistance = 0; controls.maxDistance = 5000; controls.maxPolarAngle = 2*Math.PI; /** * 模型拾取 * */ mouse.x = -10000; mouse.y = -10000; function onMouseMove( event ) { // calculate mouse position in normalized device coordinates // (-1 to +1) for both components mouse.x = ( event.clientX / window.innerWidth ) * 2 - 1; mouse.y = - ( event.clientY / window.innerHeight ) * 2 + 1; } window.addEventListener( ‘mousemove‘, onMouseMove, false ); } function pickUp() { // update the picking ray with the camera and mouse position raycaster.setFromCamera( mouse, camera ); // calculate objects intersecting the picking ray var intersects = raycaster.intersectObjects( scene.children ); for ( var i = 0; i < intersects.length; i++ ) { intersects[ i ].object.material.color.set( 0xff00ff ); } if(intersects.length === 0){ scene.children[2].material.color.set( 0xffff00 ); for(var i=3; i<scene.children.length; i++){ scene.children[i].material.color.set( 0xffffff ); } } renderer.render( scene, camera ); } function onWindowResize() { windowHalfX = window.innerWidth / 2; windowHalfY = window.innerHeight / 2; camera.aspect = window.innerWidth / window.innerHeight; camera.updateProjectionMatrix(); renderer.setSize(window.innerWidth, window.innerHeight); } var rad = 0; function render() { camera.position.set(2600, 500, 2600); camera.up = new THREE.Vector3(0, 1, 0); camera.lookAt(new THREE.Vector3(0, 500, 0)); var i = 0; for (var ix = 0; ix < AMOUNTX; ix++) { for (var iy = 0; iy < AMOUNTY; iy++) { particle = particles[i++]; particle.position.y = (Math.sin((ix + count) * 0.2) * 500) + (Math.sin((iy + count) * 0.2) * 500); particle.scale.y = (Math.sin((ix + count) * 0.3) + 1) * 3 + (Math.sin((iy + count) * 0.3) + 1) * 3; particle.scale.x = (Math.sin((ix + count) * 0.3) + 1) * 3 + (Math.sin((iy + count) * 0.3) + 1) * 3; } scene.children[2].translateY(Math.cos(ix + count/2)*5); } //模型旋转 scene.children[2].rotateY(Math.PI/180); camera.position.x = 2600*Math.cos(Math.PI/180*rad); camera.position.z = -2600*Math.sin(Math.PI/180*rad); //点光源位置 scene.children[0].position.x = 1200*Math.cos(Math.PI/180*rad+Math.PI*0.1); scene.children[0].position.z = -1200*Math.sin(Math.PI/180*rad+Math.PI*0.1); controls.update(); renderer.render(scene, camera); count += 0.1; rad += 0.2; } function animate() { requestAnimationFrame(animate); render(); pickUp(); } init(); animate();</script></html>
我们分析一下段代码，首先我们看到requestAnimationFrame，这是主循环，我们在init()初始化函数中往scene场景中添加了particle粒子，这些粒子是在XoZ平面上均匀网格散布的。然后我们主循环每次render()都改变粒子的Y坐标，修改的规则是通过sin函数进行Y轴向扰动。每次重绘我们都修改Y坐标，就实现了粒子的波动特效。
代码很简单，希望能帮助大家做出一套粒子波动的背景特效。鲫鱼非常愿意和大家讨论学习WebGL和ThreeJS的技术，欢迎大家留言，谢谢。本文系原创，如需引用请注明出处：https://www.cnblogs.com/ccentry/p/10125686.html
