1. 引言

Three.js是著名的JavaScript 3D图形库，用于浏览器中开发 3D 交互场景的 JS 引擎，可以快速的搭建三维场景

Three.js官网为：创建一个场景 – three.js docs (threejs.org)

GitHub站点为：mrdoob/three.js: JavaScript 3D Library. (github.com)

本文描述Three.js的基础使用与搭建一个场景

2. 基础使用

2.1 基础场景

使用Three.js构建一个场景，大致步骤如下：

graph LR
材质Material --> Mesh
几何体Geometry --> Mesh --> 场景Scene --> 渲染器Renderer
相机Camera --> 渲染器Renderer

按照上述流程，简要设置几个参数，就可以构建出一个简单的场景：

<!DOCTYPE html>
<html lang="en">

<head>
	<meta charset="UTF-8">
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
	<style>
		html,
		body,
		canvas {
			height: 100%;
			width: 100%;
			margin: 0;
		}
	</style>
</head>

<body>
	<canvas id="canvas"></canvas>
	<script type="module">
		import * as THREE from 'https://cdn.bootcdn.net/ajax/libs/three.js/0.151.3/three.module.js';

		const scene = new THREE.Scene();
        
		const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);
		camera.position.z = 5;
        
        const renderer = new THREE.WebGLRenderer({
			canvas: document.querySelector('#canvas')
		});
		renderer.setSize(window.innerWidth, window.innerHeight, false)
        
		const geometry = new THREE.BoxGeometry(1, 1, 1);
		const material = new THREE.MeshBasicMaterial({
			color: 0x00ff00
		});
		const cube = new THREE.Mesh(geometry, material);
		scene.add(cube);
		
		function animate() {
			requestAnimationFrame(animate);
			cube.rotation.x += 0.01;
			cube.rotation.y += 0.01;
			renderer.render(scene, camera);
		}
		animate();
	</script>
</body>

</html>

结果如下：

image-20230509113757228

2.2 光照

添加光照并修改一下材质（使其可以反光）：

graph LR
材质Material --> Mesh
几何体Geometry --> Mesh --> 场景Scene
光照Light --> 场景Scene --> 渲染器Renderer
相机Camera --> 渲染器Renderer 
<!DOCTYPE html>
<html lang="en">

<head>
	<meta charset="UTF-8">
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
	<style>
		html,
		body,
		canvas {
			height: 100%;
			width: 100%;
			margin: 0;
		}
	</style>
</head>

<body>
	<canvas id="canvas"></canvas>
	<script type="module">
		import * as THREE from 'https://cdn.bootcdn.net/ajax/libs/three.js/0.151.3/three.module.js';

		const scene = new THREE.Scene();

		const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);
		camera.position.z = 5;

		const renderer = new THREE.WebGLRenderer({
			canvas: document.querySelector('#canvas')
		});
		renderer.setSize(window.innerWidth, window.innerHeight, false)
		
		const geometry = new THREE.BoxGeometry(1, 1, 1);
		const material = new THREE.MeshPhongMaterial({
			color: 0x00ff00
		});
		const cube = new THREE.Mesh(geometry, material);
		scene.add(cube);

		const light = new THREE.DirectionalLight(0xffffff, 1);
		light.position.set(0, 0, 5);
		scene.add(light);
		
		function animate() {
			requestAnimationFrame(animate);
			cube.rotation.x += 0.01;
			cube.rotation.y += 0.01;
			renderer.render(scene, camera);
		}
		animate();
	</script>
</body>

</html>

结果如下：

image-20230509135822844

2.3 多个Mesh

添加两个Mesh到场景中，并共用一个Geometry：

graph LR
材质Material --> Mesh1
几何体Geometry --> Mesh1 --> 场景Scene
材质Material2 --> Mesh2
几何体Geometry --> Mesh2 --> 场景Scene
光照Light --> 场景Scene --> 渲染器Renderer
相机Camera --> 渲染器Renderer 
<!DOCTYPE html>
<html lang="en">

<head>
	<meta charset="UTF-8">
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
	<style>
		html,
		body,
		canvas {
			height: 100%;
			width: 100%;
			margin: 0;
		}
	</style>
</head>

<body>
	<canvas id="canvas"></canvas>
	<script type="module">
		import * as THREE from 'https://cdn.bootcdn.net/ajax/libs/three.js/0.151.3/three.module.js';

		const scene = new THREE.Scene();

		const camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);
		camera.position.z = 5;

		const renderer = new THREE.WebGLRenderer({
			canvas: document.querySelector('#canvas')
		});
		renderer.setSize(window.innerWidth, window.innerHeight, false)
		
		const geometry = new THREE.BoxGeometry(1, 1, 1);
		const material = new THREE.MeshPhongMaterial({
			color: 0x00ff00
		});
		const cube = new THREE.Mesh(geometry, material);
		scene.add(cube);

		const material2 = new THREE.MeshPhongMaterial({
			color: 0x0000ff
		});
		const cube2 = new THREE.Mesh(geometry, material2);
		cube2.position.x = 2;
		scene.add(cube2);

		const light = new THREE.DirectionalLight(0xffffff, 1);
		light.position.set(0, 0, 5);
		scene.add(light);
		
		function animate() {
			requestAnimationFrame(animate);
			cube.rotation.x += 0.01;
			cube.rotation.y += 0.01;
			renderer.render(scene, camera);
		}
		animate();
	</script>
</body>

</html>

结果如下：

image-20230509140647651

2.4 控制器

加入轨道控制器OrbitControls实现场景拖动：

graph LR
材质Material --> Mesh
几何体Geometry --> Mesh --> 场景Scene
光照Light --> 场景Scene --> 渲染器Renderer
相机Camera --> 渲染器Renderer
相机Camera --> 控制器Controls 
<!DOCTYPE html>
<html lang="en">

<head>
	<meta charset="UTF-8">
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
	<style>
		html,
		body,
		canvas {
			height: 100%;
			width: 100%;
			margin: 0;
		}
	</style>
	
</head>

<body>
	<canvas id="canvas"></canvas>

	<script type="importmap">
		{
			"imports": {
				"three": "https://unpkg.com/three/build/three.module.js",
				"three/addons/": "https://unpkg.com/three/examples/jsm/"
			}
		}
	</script>
	
	<script type="module">
		import * as THREE from 'three';
		import { OrbitControls } from 'three/addons/controls/OrbitControls.js';

		const scene = new THREE.Scene();

		const canvas = document.querySelector('#canvas');
		const camera = new THREE.PerspectiveCamera(75,  canvas.clientWidth / canvas.clientHeight , 0.1, 1000);
		camera.position.z = 5;

		const renderer = new THREE.WebGLRenderer({
			canvas: document.querySelector('#canvas')
		});
		renderer.setSize(window.innerWidth, window.innerHeight, false)
		
		const geometry = new THREE.BoxGeometry(1, 1, 1);
		const material = new THREE.MeshPhongMaterial({
			color: 0x00ff00
		});
		const cube = new THREE.Mesh(geometry, material);
		scene.add(cube);

		const light = new THREE.DirectionalLight(0xffffff, 1);
		light.position.set(0, 0, 5);
		scene.add(light);

		const controls = new OrbitControls( camera, renderer.domElement );
		
		function animate() {
			requestAnimationFrame(animate);
			cube.rotation.x += 0.01;
			cube.rotation.y += 0.01;
			renderer.render(scene, camera);
		}
		animate();
	</script>
</body>

</html>
  • 注意这里的CDN地址、加载方式有变动

结果如下：

image-20230509144649341

2.5 模型加载

加入GLTFLoader加载GLTF模型：

graph LR
材质Material --> Mesh
几何体Geometry --> Mesh --> 场景Scene
加载器Loader -->模型Model --> 场景Scene
光照Light --> 场景Scene --> 渲染器Renderer
相机Camera --> 渲染器Renderer
相机Camera --> 控制器Controls

模型下载自：three.js/Xbot.glb at dev · mrdoob/three.js · GitHub

<!DOCTYPE html>
<html lang="en">

<head>
	<meta charset="UTF-8">
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
	<style>
		html,
		body,
		canvas {
			height: 100%;
			width: 100%;
			margin: 0;
		}
	</style>
	
</head>

<body>
	<canvas id="canvas"></canvas>

	<script type="importmap">
		{
			"imports": {
				"three": "https://unpkg.com/three/build/three.module.js",
				"three/addons/": "https://unpkg.com/three/examples/jsm/"
			}
		}
	</script>
	
	<script type="module">
		import * as THREE from 'three';
		import { OrbitControls } from 'three/addons/controls/OrbitControls.js';
		import { GLTFLoader } from 'three/addons/loaders/GLTFLoader.js';

		const scene = new THREE.Scene();

		const canvas = document.querySelector('#canvas');
		const camera = new THREE.PerspectiveCamera(75,  canvas.clientWidth / canvas.clientHeight , 0.1, 1000);
		camera.position.z = 5;

		const renderer = new THREE.WebGLRenderer({
			canvas: document.querySelector('#canvas')
		});
		renderer.setSize(window.innerWidth, window.innerHeight, false)
		
		const geometry = new THREE.BoxGeometry(1, 1, 1);
		const material = new THREE.MeshPhongMaterial({
			color: 0x00ff00
		});
		const cube = new THREE.Mesh(geometry, material);
		scene.add(cube);

		const gltfLoader = new GLTFLoader();
		gltfLoader.load('./models/Xbot.glb', (gltf) => {
			scene.add(gltf.scene)
			gltf.scene.position.z = 2
		})

		const light = new THREE.DirectionalLight(0xffffff, 1);
		light.position.set(0, 0, 5);
		scene.add(light);

		const controls = new OrbitControls( camera, renderer.domElement );
		
		function animate() {
			requestAnimationFrame(animate);
			cube.rotation.x += 0.01;
			cube.rotation.y += 0.01;
			renderer.render(scene, camera);
		}
		animate();
	</script>
</body>

</html>

结果如下：

image-20230509152226585

3. 参考资料

[1] 创建一个场景 – three.js docs (threejs.org)

[2] mrdoob/three.js: JavaScript 3D Library. (github.com)

[3] three.js manual (threejs.org)