three.js 04-10 之 LineDashedMaterial 材质

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本篇介绍的 LineDashedMaterial 材质跟上一篇 LineBasicMaterial 材质基本一样，只不过 LineDashedMaterial 材质的线型是虚线而已。除了跟 LineBasicMaterial 拥有相同的属性外，它还有以下几个独特的属性：

属性描述scale （缩放比例）缩放 dashSize 和 gapSize。如果 scale 小于 1，dashSize 和 gapSize 就会增大；反之，就会缩小dashSize （短划线长度）定义虚线短划线的长度gapSize （间隔长度）定义虚线间隔的长度用法跟 LineBasicMaterial 基本一样，如下所示：

lines.computeLineDistances();var lineMaterial = new THREE.LineDashedMaterial({vertexColors: true,color: 0xffffff,dashSize: 0.6,gapSize: 0.2,scale: 1.0 // 比例越大，虚线越密；反之，虚线越疏});

唯一的区别就是，必须调用方法 computeLineDistances()。如果不调用，就不会显示出虚线效果。下面给出完整的示例，代码如下：

<!DOCTYPE html><html><head>    <title>示例 04.10 - LineDashedMaterial</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 {            /* 设置 margin 为 0，并且 overflow 为 hidden，来完成页面样式 */            margin: 0;            overflow: hidden;        }/* 统计对象的样式 */#Stats-output {position: absolute;left: 0px;top: 0px;}    </style></head><body><!-- 用于 WebGL 输出的 Div --><div id="webgl-output"></div><!-- 用于统计 FPS 输出的 Div --><div id="stats-output"></div><!-- 运行 Three.js 示例的 Javascript 代码 --><script type="text/javascript">var scene;var camera;var render;var webglRender;//var canvasRender;var controls;var stats;var guiParams;var ground;var cube;var lineMaterial;var ambientLight;var spotLight;    $(function() {stats = initStats();scene = new THREE.Scene();webglRender = new THREE.WebGLRenderer( {antialias: true, alpha: true} ); // antialias 抗锯齿webglRender.setSize(window.innerWidth, window.innerHeight);webglRender.setClearColor(0x000000, 1.0);//webglRender.shadowMap.enabled = true; // 允许阴影投射render = webglRender;camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 10000); // 2147483647camera.position.set(-30, 40, 30);var target = new THREE.Vector3(0, 0 , 0);controls = new THREE.OrbitControls(camera, render.domElement);controls.target = target;camera.lookAt(target);$('#webgl-output')[0].appendChild(render.domElement);window.addEventListener('resize', onWindowResize, false);ambientLight = new THREE.AmbientLight(0x0c0c0c);scene.add(ambientLight);spotLight = new THREE.SpotLight({color: 0xffffff});spotLight.position.set(-40, 60, -10);spotLight.castShadow = true;scene.add(spotLight);//scene.add(new THREE.AxisHelper(20));// 加入坐标轴var points = gosper(4, 60);var lines = new THREE.Geometry();var colors = [];var i = 0;points.forEach(function(e){lines.vertices.push(new THREE.Vector3(e.x, e.z, e.y));colors[i] = new THREE.Color(0xffffff);// 色调（Hue）、饱和度（Saturation）、亮度（Lightnesscolors[i].setHSL(e.x / 100 + 0.5, e.y * 20 / 300, 0.8);i++;});lines.colors = colors;lines.computeLineDistances(); // 必须调用，否则不会有虚线效果lineMaterial = new THREE.LineDashedMaterial({vertexColors: true,color: 0xffffff,dashSize: 0.6,gapSize: 0.2,scale: 1.0 // 比例越大，虚线越密；反之，虚线越疏});var line = new THREE.Line(lines, lineMaterial);line.position.set(25, -30, -60);        scene.add(line);/** 用来保存那些需要修改的变量 */guiParams = new function() {this.rotationSpeed = 0.01;}/** 定义 dat.GUI 对象，并绑定 guiParams 的几个属性 *///var gui = new dat.GUI();renderScene();    });/** 渲染场景 */function renderScene() {stats.update();rotateMesh(); // 旋转物体requestAnimationFrame(renderScene);render.render(scene, camera);}/** 初始化 stats 统计对象 */function initStats() {stats = new Stats();stats.setMode(0); // 0 为监测 FPS；1 为监测渲染时间$('#stats-output').append(stats.domElement);return stats;}/** 当浏览器窗口大小变化时触发 */function onWindowResize() {camera.aspect = window.innerWidth / window.innerHeight;camera.updateProjectionMatrix();render.setSize(window.innerWidth, window.innerHeight);}/** 旋转物体 */function rotateMesh() {scene.traverse(function(mesh) {if (mesh instanceof THREE.Line && mesh != ground) {//mesh.rotation.x += guiParams.rotationSpeed;//mesh.rotation.y += guiParams.rotationSpeed;mesh.rotation.z += guiParams.rotationSpeed;}});}/** 高斯帕曲线 */function gosper(a, b) {var turtle = [0, 0, 0];var points = [];var count = 0;rg(a, b, turtle); // turtle: 龟壳图案return points;function rt(x) {turtle[2] += x;}function lt(x) {turtle[2] -= x;}function fd(dist) {//ctx.beginPath();points.push({x: turtle[0], y: turtle[1], z: Math.sin(count) * 5});//ctx.moveTo(turtle[0], turtle[1]);var dir = turtle[2] * (Math.PI / 180);turtle[0] += Math.cos(dir) * dist;turtle[1] += Math.sin(dir) * dist;points.push({x: turtle[0], y: turtle[1], z: Math.sin(count) * 5});            //ctx.lineTo(turtle[0], turtle[1]);            //ctx.stroke();}function rg(st, ln, turtle) {st--;ln = ln / 2.6457;if (st > 0) {//ctx.strokeStyle = '#111';rg(st, ln, turtle);rt(60);gl(st, ln, turtle);rt(120);gl(st, ln, turtle);lt(60);rg(st, ln, turtle);lt(120);rg(st, ln, turtle);rg(st, ln, turtle);lt(60);gl(st, ln, turtle);rt(60);}if (st == 0) {fd(ln);rt(60);fd(ln);rt(120);fd(ln);lt(60);fd(ln);lt(120);fd(ln);fd(ln);lt(60);fd(ln);rt(60)}}function gl(st, ln, turtle) {st--;ln = ln / 2.6457;if (st > 0) {//ctx.strokeStyle = '#555';lt(60);rg(st, ln, turtle);rt(60);gl(st, ln, turtle);gl(st, ln, turtle);rt(120);gl(st, ln, turtle);rt(60);rg(st, ln, turtle);lt(120);rg(st, ln, turtle);lt(60);gl(st, ln, turtle);}if (st == 0) {lt(60);fd(ln);rt(60);fd(ln);fd(ln);rt(120);fd(ln);rt(60);fd(ln);lt(120);fd(ln);lt(60);fd(ln);}}}</script></body></html>

到此，three.js 库中常用的材质基本就已经介绍完了，剩下的读者可以自行扩展。

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