本篇介紹的 LineDashedMaterial 材質跟上一篇 LineBasicMaterial 材質基本一樣，只不過 LineDashedMaterial 材質的線型是虛線而已。除了跟 LineBasicMaterial 擁有相同的屬性外，它還有以下幾個獨特的屬性：
| 屬性 | 描述 |
|---|---|
| scale （縮放比例） | 縮放 dashSize 和 gapSize。如果 scale 小於 1，dashSize 和 gapSize 就會增大；反之，就會縮小 |
| dashSize （短劃線長度） | 定義虛線短劃線的長度 |
| gapSize （間隔長度） | 定義虛線間隔的長度 |
lines.computeLineDistances();
var lineMaterial = new THREE.LineDashedMaterial({
vertexColors: true,
color: 0xffffff,
dashSize: 0.6,
gapSize: 0.2,
scale: 1.0 // 比例越大，虛線越密；反之，虛線越疏
});<!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 {
/* 設置 margin 爲 0，並且 overflow 爲 hidden，來完成頁面樣式 */
margin: 0;
overflow: hidden;
}
/* 統計對象的樣式 */
#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>
<!-- 運行 Three.js 示例的 Javascript 代碼 -->
<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 抗鋸齒
webglRender.setSize(window.innerWidth, window.innerHeight);
webglRender.setClearColor(0x000000, 1.0);
//webglRender.shadowMap.enabled = true; // 允許陰影投射
render = webglRender;
camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 10000); // 2147483647
camera.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));// 加入座標軸
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);
// 色調（Hue）、飽和度（Saturation）、亮度（Lightness
colors[i].setHSL(e.x / 100 + 0.5, e.y * 20 / 300, 0.8);
i++;
});
lines.colors = colors;
lines.computeLineDistances(); // 必須調用，否則不會有虛線效果
lineMaterial = new THREE.LineDashedMaterial({
vertexColors: true,
color: 0xffffff,
dashSize: 0.6,
gapSize: 0.2,
scale: 1.0 // 比例越大，虛線越密；反之，虛線越疏
});
var line = new THREE.Line(lines, lineMaterial);
line.position.set(25, -30, -60);
scene.add(line);
/** 用來保存那些需要修改的變量 */
guiParams = new function() {
this.rotationSpeed = 0.01;
}
/** 定義 dat.GUI 對象，並綁定 guiParams 的幾個屬性 */
//var gui = new dat.GUI();
renderScene();
});
/** 渲染場景 */
function renderScene() {
stats.update();
rotateMesh(); // 旋轉物體
requestAnimationFrame(renderScene);
render.render(scene, camera);
}
/** 初始化 stats 統計對象 */
function initStats() {
stats = new Stats();
stats.setMode(0); // 0 爲監測 FPS；1 爲監測渲染時間
$('#stats-output').append(stats.domElement);
return stats;
}
/** 當瀏覽器窗口大小變化時觸發 */
function onWindowResize() {
camera.aspect = window.innerWidth / window.innerHeight;
camera.updateProjectionMatrix();
render.setSize(window.innerWidth, window.innerHeight);
}
/** 旋轉物體 */
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;
}
});
}
/** 高斯帕曲線 */
function gosper(a, b) {
var turtle = [0, 0, 0];
var points = [];
var count = 0;
rg(a, b, turtle); // turtle: 龜殼圖案
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>未完待續···