three.js 03-04 之 DirectionalLight 光源

来源：互联网发布：android使用数据库登录编辑：程序博客网时间：2024/06/05 15:25

这一篇我们来看看剩下的最后一个基础光源 DirectionalLight （方向光或叫平行光）光源。这个光源可以看做是距离很远很远的光源，就像太阳。太阳离我们是如此的遥远，以至于所有的光线到达地球时都成了相互平行的光线了。方向光跟聚光灯光源之间的主要差别是：方向光不像聚光灯那样离目标越远越暗淡，被方向光光源照亮的整个区域接收到的光的强度是一样的。

下面来看一个完整的示例，代码如下所示：

<!DOCTYPE html><html><head>    <title>示例 03.04 - 方向光光源</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 controls;var stats;var guiControls;var cube;var sphere;var directionalLight;var shadowCameraHelper;    $(function() {stats = initStats();scene = new THREE.Scene();camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000); // 2147483647camera.position.set(-30, 40, 30);render = new THREE.WebGLRenderer( {antialias: true} ); // antialias 抗锯齿render.setSize(window.innerWidth, window.innerHeight);render.setClearColor(0xEEEEEE);render.shadowMap.enabled = true; // 允许阴影投射$('#WebGL-output')[0].appendChild(render.domElement);window.addEventListener('resize', onWindowResize, false);var target = new THREE.Vector3(scene.position.x, scene.position.y ,scene.position.z);controls = new THREE.OrbitControls(camera, render.domElement);controls.target = target;camera.lookAt(target);scene.add(new THREE.AxesHelper(20));// 加入坐标轴// 加入一个平面var planeGeometry = new THREE.PlaneGeometry(600, 200, 20, 20);var planeMaterial =  new THREE.MeshLambertMaterial( {color: 0xFFFFFF} );var plane = new THREE.Mesh(planeGeometry, planeMaterial);plane.rotation.x = -0.5 * Math.PI; // 沿着 X轴旋转-90°plane.position.x = 15; // 沿着 x轴右移 15个单位plane.position.y = 0; // y轴为 0plane.position.z = 0; // z轴为 0plane.receiveShadow = true; // 非线框几何平面接收阴影scene.add(plane);// 加入一个立方体var cubeGeometry = new THREE.BoxGeometry(4, 4, 4);var cubeMaterial = new THREE.MeshLambertMaterial( {color: 0xFF7777} );cube = new THREE.Mesh(cubeGeometry, cubeMaterial);cube.position.x = -4;cube.position.y = 3;cube.position.z = 0;cube.castShadow = true; // 立方体投射阴影scene.add(cube);// 加入一个球体var sphereGeometry = new THREE.SphereGeometry(4, 20, 20);var sphereMaterial = new THREE.MeshLambertMaterial( {color: 0x7777FF} );sphere = new THREE.Mesh(sphereGeometry, sphereMaterial);sphere.position.x = 20;sphere.position.y = 4;sphere.position.z = 2;sphere.castShadow = true; // 球体投射阴影scene.add(sphere);// 加入一个环境光源var ambientLight = new THREE.AmbientLight(0x0c0c0c);scene.add(ambientLight);// 加入一个小球体来表示聚光灯位置sphereGeometry = new THREE.SphereGeometry(0.2, 20, 20);sphereMaterial = new THREE.MeshBasicMaterial( {color: 0xac6c25} );var lightMesh = new THREE.Mesh(sphereGeometry, sphereMaterial);// 加入一个方向光：color 颜色, intensity 强度directionalLight = new THREE.DirectionalLight( 0xff5808, 0.5);directionalLight.position.set(-40, 60, -10);directionalLight.castShadow = true; // 光源产生阴影directionalLight.distance = 0;directionalLight.shadow.mapSize.set(2048, 2048); // 必须是 2的幂，默认值为 512directionalLight.shadow.camera.near = 2;directionalLight.shadow.camera.far = 100;directionalLight.shadow.camera.left = -50;directionalLight.shadow.camera.right = 50;directionalLight.shadow.camera.top = 50;directionalLight.shadow.camera.bottom = -50;directionalLight.target = plane;directionalLight.add(lightMesh);scene.add(directionalLight);/** 用来保存那些需要修改的变量 */guiControls = new function() {this.rotationSpeed = 0.02;this.bouncingSpeed = 0.04;this.ambientColor = '#1c1c1c';this.pointColor = '#ff5808';this.intensity = 1;this.distance = 0;this.debug = true;this.castShadow = true;this.disableLight = false;this.target = 'Plane';this.stopMoveLight = false;}/** 定义 dat.GUI 对象，并绑定 guiControls 的两个属性 */var gui = new dat.GUI();gui.addColor(guiControls, 'ambientColor').onChange( function(e) {ambientLight.color = new THREE.Color(e);});gui.addColor(guiControls, 'pointColor').onChange( function(e) {directionalLight.color = new THREE.Color(e);});gui.add(guiControls, 'intensity', 0, 3).onChange( function(e) {directionalLight.intensity = e;});gui.add(guiControls, 'distance', 0, 200).onChange( function(e) {directionalLight.distance = e;});gui.add(guiControls, 'debug').onChange(function(e) {updateShadowCamera();});gui.add(guiControls, 'castShadow').onChange(function(e) {directionalLight.castShadow = e;});gui.add(guiControls, 'disableLight').onChange(function(e) {directionalLight.visible = !e;});gui.add(guiControls, 'target', ['Plane', 'Cube', 'Sphere']).onChange(function(e) {switch (e) {case 'Plane':directionalLight.target = plane;break;case 'Cube':directionalLight.target = cube;break;case 'Sphere':directionalLight.target = sphere;break;}});gui.add(guiControls, 'stopMoveLight').onChange(function(e){this.stopMoveLight = e;});function updateShadowCamera() {scene.remove(scene.getObjectByName('shadowCameraHelper'));if (guiControls.debug) {shadowCameraHelper = new THREE.CameraHelper(directionalLight.shadow.camera);shadowCameraHelper.name = "shadowCameraHelper";scene.add(shadowCameraHelper);}}updateShadowCamera();renderScene();    });/** 渲染场景 */function renderScene() {stats.update();rotateCube(); // 旋转立方体bounceSphere(); // 弹跳球体moveLight(); // 移动点光源及其小球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);}/** 转动立方体 */function rotateCube() {cube.rotation.x += guiControls.rotationSpeed;cube.rotation.y += guiControls.rotationSpeed;cube.rotation.z += guiControls.rotationSpeed;}/** 弹跳球体 */var step = 0;function bounceSphere() {step += guiControls.bouncingSpeed;sphere.position.x = 20 + (10 * Math.cos(step));sphere.position.y = 2 + (10 * Math.abs(Math.sin(step)));}/** 移动点光源及其小球 */var phase = 0;function moveLight() {if (guiControls.stopMoveLight || !directionalLight)return;phase += guiControls.rotationSpeed;directionalLight.position.x = 15 + 30 * (Math.cos(phase));directionalLight.position.y = 30 * (Math.sin(phase));}</script></body></html>

正如你所看到的，整个场景里没有那种锥形的光线。这种光源只用 direction 方向、color 颜色和 intensity 强度属性来计算颜色和阴影。方向光的属性大都与聚光灯光源相同，例如 position、target、intensity、distance、castShadow、shadow.camera.near、shadow.camera.far、shadow.camera.left、shadow.camera.right、shadow.camera.top、shadow.camera.bottom、shadow.mapSize.width、shadow.mapSize.height 和 shadow.bias 等。

细心的读者可能会发现，前面那个 SpotLight 聚光灯的例子中，我们必须定义生成阴影的光锥。但对于 DirectionalLight 方向光光源，由于所有光线都是平行的，所有不会有光锥的概念，取而代之的是一个方块，正如此示例中显示出来的 THREE.CameraHelper() 对象那样。这个方块包围对象的空间定义得越紧密，投影的效果越好。这主要是通过一些这些属性来定义的：

directionalLight.shadow.camera.near = 2;directionalLight.shadow.camera.far = 100;directionalLight.shadow.camera.left = -50;directionalLight.shadow.camera.right = 50;directionalLight.shadow.camera.top = 50;directionalLight.shadow.camera.bottom = -50;

我们可以把这些设置跟之前“three.js 02-05 之相机”中的 OrthographicCamera 正投影相机的相关用法对比参照一下，含义几乎是相同的。

未完待续···

阅读全文

1 0