關於 three.js 庫中的基礎材質類型基本上就已經介紹完了。本篇開始介紹 three.js 庫中提供的高級材質。例如比較常用的 MeshPhongMaterial 和 MeshLambertMaterial 兩種材質。以及另一種最通用，但卻最難用的 ShaderMaterial 材質，通過它，你可以創建自己的着色程序、定義材質以及物體如何顯示等。
我們先來看看 MeshLambertMaterial 這種用於暗淡、不光亮表面的材質。這種材質會對光源產生反應。這種材質除了前面提到的 color、opacity、transparent、flatShading、blending、depthTest、depthWrite、wirreframe、wireframeLinewidth、wireframeLinecap、wireframeLinejoin、vertexColors 及 fog 等屬性外，還有兩個比較特殊的 ambient 及 emissive 屬性，具體參考如下表所示描述：
| 屬性 | 描述 |
|---|---|
| ambient （環境光顏色） | 這僅僅是該材質的環境色。跟之前提到過的 AmbientLight 光源一起使用。這個顏色會與 AmbientLight 光源的顏色相乘。默認爲白色 |
| emissive （自發光顏色） | 這個是材質自發光的顏色。它其實並不像一個光源，只是一種不受光源照射影響的純粹的顏色 |
<!DOCTYPE html>
<html>
<head>
<title>示例 04.06 - MeshLambertMaterial</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 sphere;
var plane;
var activeMesh;
var meshMaterial;
var ambientLight;
var spotLight;
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(0xeeeeee, 1.0);
webglRender.shadowMap.enabled = true; // 允許陰影投射
render = webglRender;
camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 30, 1000); // 2147483647
camera.position.set(-45.5, 68.2, 90.9);
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(0xffffff);
spotLight.position.set(-30, 60, 60);
spotLight.castShadow = true;
scene.add(spotLight);
cameraHelper = new THREE.CameraHelper(spotLight.shadow.camera);
scene.add(cameraHelper);
// 加入一個平面
var groundGeometry = new THREE.PlaneGeometry(100, 100, 4, 4);
var groundMaterial = new THREE.MeshBasicMaterial({color: 0x777777});
ground = new THREE.Mesh(groundGeometry, groundMaterial);
ground.rotation.set(-0.5 * Math.PI, 0, 0); // 沿着 X軸旋轉-90°
scene.add(ground);
// 定義 cube, sphere, plane
var cubeGeometry = new THREE.BoxGeometry(15, 15, 15);
var sphereGeometry = new THREE.SphereGeometry(14, 20, 20);
var planeGeometry = new THREE.PlaneGeometry(14, 14, 4, 4);
// 材質
meshMaterial = new THREE.MeshLambertMaterial({color: 0x7777ff, transparent: true, opacity: 0.5});
cube = new THREE.Mesh(cubeGeometry, meshMaterial);
sphere = new THREE.Mesh(sphereGeometry, meshMaterial);
plane = new THREE.Mesh(planeGeometry, meshMaterial);
cube.castShadow = true;
sphere.castShadow = true;
plane.castShadow = true;
cube.position.set(0, 12, 0);
sphere.position.set(0, 14, 0);
plane.position.set(0, 12, 0);
/** 用來保存那些需要修改的變量 */
guiParams = new function() {
this.rotationSpeed = 0.02;
this.opacity = meshMaterial.opacity;
this.transparent = meshMaterial.transparent;
this.visible = meshMaterial.visible;
this.ambient = '#ff0000';
this.emissive = '#c31111';
this.side = 'front';
this.color = '#7777ff';
this.selectedMesh = 'cube';
this.spotLight = true;
this.addMesh = function(e) {
scene.remove(activeMesh);
switch (e) {
case "cube":
activeMesh = cube;
break;
case "sphere":
activeMesh = sphere;
break;
case "plane":
activeMesh = plane;
break;
}
scene.add(activeMesh);
};
this.updateMaterial = function() {
meshMaterial.opacity = this.opacity;
meshMaterial.transparent = this.transparent;
meshMaterial.visible = this.visible;
meshMaterial.ambient = new THREE.Color(this.ambient);
meshMaterial.emissive = new THREE.Color(this.emissive);
meshMaterial.color = new THREE.Color(this.color);
switch (this.side) {
case "front":
meshMaterial.side = THREE.FrontSide;
break;
case "back":
meshMaterial.side = THREE.BackSide;
break;
case "double":
meshMaterial.side = THREE.DoubleSide;
break;
}
meshMaterial.needsUpdate = true;
}
}
/** 定義 dat.GUI 對象，並綁定 guiParams 的幾個屬性 */
var gui = new dat.GUI();
var folder = gui.addFolder('Mesh');
folder.open();
folder.add(guiParams, 'opacity', 0.1, 1.0).onChange(function(e) {
guiParams.updateMaterial();
});
folder.add(guiParams, 'transparent').onChange(function(e) {
guiParams.updateMaterial();
});
folder.addColor(guiParams, 'ambient').onChange(function(e) {
guiParams.updateMaterial();
});
folder.addColor(guiParams, 'emissive').onChange(function(e) {
guiParams.updateMaterial();
});
folder.add(guiParams, 'visible').onChange(function(e) {
guiParams.updateMaterial();
});
folder.add(guiParams, 'side', ['front', 'back', 'double']).onChange(function(e) {
console.log(e);
guiParams.updateMaterial();
});
folder.addColor(guiParams, 'color').onChange(function(e) {
guiParams.updateMaterial();
});
folder.add(guiParams, 'selectedMesh', ['cube', 'sphere', 'plane']).onChange(function(e) {
guiParams.addMesh(e);
});
gui.add(guiParams, 'spotLight').onChange(function(e) {
scene.remove(spotLight);
scene.remove(cameraHelper);
if (e) {
scene.add(spotLight);
scene.add(cameraHelper);
}
});
guiParams.updateMaterial();
guiParams.addMesh(guiParams.selectedMesh);
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.Mesh && mesh != ground) {
//mesh.rotation.x += guiParams.rotationSpeed;
mesh.rotation.y += guiParams.rotationSpeed;
//mesh.rotation.z += guiParams.rotationSpeed;
}
});
}
</script>
</body>
</html>未完待續···