three.js 07-04 之 Points 粒子系統
阿新 • • 發佈:2019-02-02
前面都是在介紹 如何通過 THREE.Sprite 來構建粒子系統。本篇我們來介紹一下如何通過 THREE.Points 及 THREE.PointsMaterial 來構建粒子系統。我們先來看一個完整的示例,程式碼如下所示:
其中用到了一個外部圖片,在 three.js 釋出包裡可以找到,路徑是 examples/textures/sprites/ball.png。這個示例的效果如下圖所示:<!DOCTYPE html> <html> <head> <title>示例 07.01 - Particles</title> <script src="../build/three.js"></script> <script src="../build/js/controls/OrbitControls.js"></script> <script src="../build/js/libs/stats.min.js"></script> <script src="../build/js/libs/dat.gui.min.js"></script> <script src="../jquery/jquery-3.2.1.min.js"></script> <style> body { /* 設定 margin 為 0,並且 overflow 為 hidden,來完成頁面樣式 */ margin: 0; overflow: hidden; } /* 統計物件的樣式 */ #Stats-output { position: absolute; left: 0px; top: 0px; } </style> </head> <body> <!-- 用於 WebGL 輸出的 Div --> <div id="webgl-output"></div> <!-- 用於統計 FPS 輸出的 Div --> <div id="stats-output"></div> <!-- 執行 Three.js 示例的 Javascript 程式碼 --> <script type="text/javascript"> var scene; var camera; var render; var webglRender; //var canvasRender; var controls; var stats; var guiParams; var particles; var ambientLight; var spotLight; var axesHelper; //var cameraHelper; $(function() { stats = initStats(); scene = new THREE.Scene(); webglRender = new THREE.WebGLRenderer( {antialias: true, alpha: true} ); // antialias 抗鋸齒 webglRender.setSize(window.innerWidth, window.innerHeight); webglRender.setClearColor(0x0F0F0F, 1.0); // 0xeeeeee webglRender.shadowMap.enabled = true; // 允許陰影投射 render = webglRender; camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.01, 2147483647); // 2147483647 camera.position.set(0, 0, 200); var target = new THREE.Vector3(10, 0 , 0); controls = new THREE.OrbitControls(camera, render.domElement); controls.target = target; camera.lookAt(target); $('#webgl-output')[0].appendChild(render.domElement); window.addEventListener('resize', onWindowResize, false); // 加入一個座標軸:X(橙色)、Y(綠色)、Z(藍色) //axesHelper = new THREE.AxesHelper(60); //scene.add(axesHelper); ambientLight = new THREE.AmbientLight(0x0c0c0c); scene.add(ambientLight); spotLight = new THREE.SpotLight(0xffffff); spotLight.position.set(0, 260, 230); spotLight.shadow.mapSize.width = 5120; // 必須是 2的冪,預設值為 512 spotLight.shadow.mapSize.height = 5120; // 必須是 2的冪,預設值為 512 spotLight.castShadow = true; scene.add(spotLight); //cameraHelper = new THREE.CameraHelper(spotLight.shadow.camera); //scene.add(cameraHelper); // 建立粒子 createParticles(); /** 用來儲存那些需要修改的變數 */ guiParams = new function() { this.rotationSpeed = 0.002; } /** 定義 dat.GUI 物件,並繫結 guiParams 的幾個屬性 */ var gui = new dat.GUI(); gui.add(guiParams, 'rotationSpeed', 0, 0.02, 0.001); renderScene(); }); /** 渲染場景 */ function renderScene() { stats.update(); rotateMesh(); // 旋轉物體 requestAnimationFrame(renderScene); render.render(scene, camera); } /** 初始化 stats 統計物件 */ function initStats() { stats = new Stats(); stats.setMode(0); // 0 為監測 FPS;1 為監測渲染時間 $('#stats-output').append(stats.domElement); return stats; } /** 當瀏覽器視窗大小變化時觸發 */ function onWindowResize() { camera.aspect = window.innerWidth / window.innerHeight; camera.updateProjectionMatrix(); render.setSize(window.innerWidth, window.innerHeight); } /** 旋轉物體 */ var step = 0; function rotateMesh() { step += guiParams.rotationSpeed; for (var i = 0; i < scene.children.length; i++) { var mesh = scene.children[i]; if (mesh instanceof THREE.Points) { //mesh.rotation.x = i < 4 ? step : -step; mesh.rotation.y = i < 4 ? step : -step; //mesh.rotation.z = i < 4 ? step : -step; // 變顏色 var h = ( 360 * ( 1.0 + step ) % 360 ) / 360; mesh.material.color.setHSL(h, mesh.material.color.getHSL().s, mesh.material.color.getHSL().l); } }; } /** 從 Geometry 建立粒子 */ function createParticles() { // 每個 Geometry 中模擬5萬個點 var geometry = new THREE.Geometry(); for (var i = 0; i < 50000; i++) { var vertext = new THREE.Vector3( Math.random() * 2000 - 1000, Math.random() * 2000 - 1000, Math.random() * 2000 - 1000 ); geometry.vertices.push(vertext); } var loader = new THREE.TextureLoader(); var sprite = loader.load('../examples/textures/sprites/ball.png'); var color = [1.0, 0.2, 0.3]; var size = 20; // 建立粒子 var pointsMaterial = new THREE.PointsMaterial( {size: size, map: sprite, depthTest: false, transparent: true, opacity: 1.0, blending: THREE.AdditiveBlending} ); pointsMaterial.color.setRGB(color[0], color[1], color[2]); particles = new THREE.Points(geometry, pointsMaterial); particles.rotation.set(Math.random() * 6, Math.random() * 6, Math.random() * 6); scene.add(particles); } </script> </body> </html>