three.js 05-06 之 CylinderGeometry 几何体

最新推荐文章于 2025-03-11 11:14:36 发布

zhulx_sz

最新推荐文章于 2025-03-11 11:14:36 发布

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本文链接：https://blog.youkuaiyun.com/zhulx_sz/article/details/78835578

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今天将要介绍的是 CylinderGeometry 几何体。这也是一种非常简单的三维几何体，你甚至不需要指定任何参数就能创建出一个圆柱体。下面给出了常用的几个属性：

属性	描述
radiusTop	可选。此属性定义圆柱体顶部圆半径。默认值是 20
radiusBottom	可选。此属性定义圆柱体底部圆半径。默认值是 20
height	可选。此属性定义圆柱体的高度。默认值是 100
radiusSegments	可选。此属性定义圆柱体的上下部的圆截面分成多少段。默认值是 8
heightSegments	可选。此属性定义圆柱体竖直方向上分成多少段。默认值是 1
openEnded	可选。此属性定义圆柱体的顶部和底部是否为打开。默认值是 false

对于上表中提到的相关参数，想必不用多说，你也应该很清楚他们的含义和用法了，下面给出完整示例，代码如下：

<!DOCTYPE html>
<html>
<head>
    <title>示例 05.06 - CylinderGeometry</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 box;
	//var sphere;
	var cylinder;
	//var plane;
	
	var meshMaterial;
	
	var ambientLight;
	var spotLight;
	//var cameraHelper;

    $(function() {
		stats = initStats();
		scene = new THREE.Scene();
		
		webglRender = new THREE.WebGLRenderer( {antialias: true, alpha: true} ); // antialias 抗锯齿
		webglRender.setSize(window.innerWidth, window.innerHeight);
		webglRender.setClearColor(0xeeeeee, 1.0);
		webglRender.shadowMap.enabled = true; // 允许阴影投射
		render = webglRender;
		
		camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.01, 1000); // 2147483647
		camera.position.set(-45.5, 68.2, 90.9);
		
		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);
		
		ambientLight = new THREE.AmbientLight(0x0c0c0c);
		scene.add(ambientLight);
		
		spotLight = new THREE.SpotLight(0xffffff);
        spotLight.position.set(0, 60, 30);
		spotLight.shadow.mapSize.width = 5120; // 必须是 2的幂，默认值为 512
		spotLight.shadow.mapSize.height = 5120; // 必须是 2的幂，默认值为 512
        spotLight.castShadow = true;
        scene.add(spotLight);
		//cameraHelper = new THREE.CameraHelper(spotLight.shadow.camera);
		//scene.add(cameraHelper);
		
		// 加入一个地面
		var groundGeometry = new THREE.PlaneGeometry(100, 100, 4, 4);
		var groundMaterial = new THREE.MeshLambertMaterial({color: 0x777777}); // MeshBasicMaterial 材质不能接收阴影
		ground = new THREE.Mesh(groundGeometry, groundMaterial);
		ground.rotation.set(-0.5 * Math.PI, 0, 0); // 沿着 X轴旋转-90°
		ground.receiveShadow = true;
		scene.add(ground);
		
		// 材质
        meshMaterial = [
			new THREE.MeshNormalMaterial({side: THREE.DoubleSide}),
			new THREE.MeshBasicMaterial({wireframe: true})
		];
		
		/** 用来保存那些需要修改的变量 */
		guiParams = new function() {
			this.rotationSpeed = 0.02;
			
			this.radiusTop = 10;
			this.radiusBottom = 10;
			this.height = 20;
			this.radiusSegments = 16;
			this.heightSegments = 4;
			this.openEnded = true;
			this.thetaStart = 0;
			this.thetaLength = 2 * Math.PI;
		}
		/** 定义 dat.GUI 对象，并绑定 guiParams 的几个属性 */
		var gui = new dat.GUI();
		gui.add(guiParams, 'radiusTop', -10, 50, 1).onChange(function(e){updateMesh()});
		gui.add(guiParams, 'radiusBottom', -10, 50, 1).onChange(function(e){updateMesh()});
		gui.add(guiParams, 'height', 1, 50, 1).onChange(function(e){updateMesh()});
		gui.add(guiParams, 'radiusSegments', 2, 20, 1).onChange(function(e){updateMesh()});
		gui.add(guiParams, 'heightSegments', 1, 20, 1).onChange(function(e){updateMesh()});
		gui.add(guiParams, 'openEnded').onChange(function(e){updateMesh()});
		gui.add(guiParams, 'thetaStart', 0, Math.PI, 0.01).onChange(function(e){updateMesh()});
		gui.add(guiParams, 'thetaLength', 0, 2 * Math.PI, 0.01).onChange(function(e){updateMesh()});
		
		updateMesh();
		
		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 */
	var step = 0;
	function rotateMesh() {
		step += guiParams.rotationSpeed;
		scene.traverse(function(mesh) {
			if ((mesh instanceof THREE.Mesh || mesh instanceof THREE.Line) && mesh != ground) {
				//mesh.rotation.x = step;
				mesh.rotation.y = step;
				//mesh.rotation.z = step;
			}
		});
	}
	
	function updateMesh() {
		scene.remove(cylinder);
		
		// 定义 cylinder
		var cylinderGeometry = new THREE.CylinderGeometry(guiParams.radiusTop, guiParams.radiusBottom, guiParams.height, guiParams.radiusSegments, guiParams.heightSegments, guiParams.openEnded, guiParams.thetaStart, guiParams.thetaLength);
		cylinder = new THREE.SceneUtils.createMultiMaterialObject(cylinderGeometry, meshMaterial);
		cylinder.children[1].castShadow = true; // cylinder.children[0] 的材质是 MeshNormalMaterial，不能投射阴影
		cylinder.position.set(0, guiParams.height / 2 + 3, 0);
		scene.add(cylinder);
	}

</script>
</body>
</html>

需要注意的是，圆柱体的顶部和底部半径可以设置为负数。如果这样设置的话，你就可以创建出一个类似沙漏的图形了。
未完待续···