69 - three.js 笔记 - 使用光照贴图 lightMap 创建假阴影

MateriallightMap属性,是光照贴图,使用光照贴图可以模拟出真实的阴影效果,但是阴影的位置不能随着随着物体的移动而移动。

1、示例

示例
http://ithanmang.com/threeJs/home/201809/20180905/06-lightMap-texture.html
效果
这里写图片描述
下面的阴影是通过光照贴图加载进来的,如下面的关照贴图
这里写图片描述

2、使用步骤

2.1、创建实例
 let lm = new THREE.TextureLoader().load('../../textures/lightmap/lm-1.png');
 planeGround.material.lightMap = lm;

将平面的材质的lightMap设置

2.3、指定UV映射
planeGround.geometry.faceVertexUvs[1] = planeGround.geometry.faceVertexUvs[0];

为光照贴图指定uv映射,将纹理的那一部分映射到表面,只有这样才能将关照贴图与其它贴图分别开来。

3、示例代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <link rel="icon" href="../../../three.png">
    <title>使用光照贴图创建假阴影</title>
    <style>
        body {
            margin: 0;
            overflow: hidden; /* 溢出隐藏 */
        }

        #loading {
            position: fixed;
            top: 50%;
            left: 50%;
            color: #FFFFFF;
            font-size: 20px;
            margin-top: -30px;
            margin-left: -40px;
        }
    </style>
    <script src="../../libs/build/three-r93.js"></script>
    <script src="../../libs/examples/js/Detector.js"></script>
    <script src="../../libs/examples/js/libs/dat.gui.min.js"></script>
    <script src="../../libs/examples/js/libs/stats.min.js"></script>
    <script src="../../libs/examples/js/controls/OrbitControls.js"></script>
</head>
<body>
<p id="loading">loading......</p>
<script>

    let scene, camera, renderer, controls, guiControls;
    let stats = initStats();

    /* 场景 */
    function initScene() {

        scene = new THREE.Scene();
        scene.background = new THREE.Color(0x050505);

    }

    /* 相机 */
    function initCamera() {

        camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 10000);
        camera.position.set(0, 50, -90);
        camera.lookAt(new THREE.Vector3(0, 0, 0));

    }

    /* 渲染器 */
    function initRender() {

        renderer = new THREE.WebGLRenderer({antialias: true});
        renderer.setSize(window.innerWidth, window.innerHeight);

        document.body.appendChild(renderer.domElement);

    }

    /* 灯光 */
    function initLight() {

        scene.add(new THREE.AmbientLight(0x0c0c0c));

        let spotLight1 = new THREE.SpotLight(0xffffff);
        spotLight1.position.set(-400, -400, -400);

        let spotLight2 = new THREE.SpotLight(0xffffff);
        spotLight2.position.set(400, 400, 400);

        scene.add(spotLight1);
        scene.add(spotLight2);

    }

    /* 控制器 */
    function initControls() {

        /* 地图控件 */
        controls = new THREE.OrbitControls(camera, renderer.domElement);

        /* 属性参数 */

    }

    /* 调试插件 */
    function initGui() {

        guiControls = new function () {

            this.normalScale = 1;

        };

        let gui = new dat.GUI();
        gui.add(guiControls, 'normalScale', -2, 2).onChange(function (e) {

            box1.material.normalScale.set(e, e);

        });


    }

    /* 场景中的内容 */
    let box1;
    let box2;

    function initContent() {
        let planeGround = createMesh(new THREE.PlaneGeometry(95, 95, 1, 1), 'floor-wood.jpg');
        box1 = createMesh(new THREE.BoxGeometry(10, 10, 10), 'plaster.jpg', 'plaster-normal.jpg');
        box2 = createMesh(new THREE.BoxGeometry(10, 10, 10), 'plaster.jpg');

        let lm = new THREE.TextureLoader().load('../../textures/lightmap/lm-1.png');


        box1.translateX(10);
        box2.translateX(-10);
        box1.translateY(10);
        box2.translateY(10);

        planeGround.rotateX(Math.PI * -0.5);
        planeGround.material.lightMap = lm;

        planeGround.geometry.faceVertexUvs[1] = planeGround.geometry.faceVertexUvs[0];

        scene.add(planeGround);
        scene.add(box1);
        scene.add(box2);

    }

    /* 移除加载元素 */
    function removeLoading() {

        document.getElementById('loading').style.display = 'none';

    }

    /* 创建带有纹理的网格 */
    function createMesh(geometry, imageUrl, normalMap) {

        let loader = new THREE.TextureLoader();
        let texture = loader.load('../../textures/general/' + imageUrl);


        let material = new THREE.MeshPhongMaterial();
        material.map = texture;

        if (normalMap !== undefined) {

            let normal = loader.load('../../textures/general/' + normalMap, function () {
                removeLoading();
            });
            material.normalMap = normal;

        }


        let mesh = new THREE.Mesh(geometry, material);

        return mesh;

    }

    /* 性能插件 */
    function initStats() {

        let stats = new Stats();

        document.body.appendChild(stats.domElement);

        return stats;

    }

    /* 窗口变动触发 */
    function onWindowResize() {

        camera.aspect = window.innerWidth / window.innerHeight;
        camera.updateProjectionMatrix();
        renderer.setSize(window.innerWidth, window.innerHeight);

    }

    /* 数据更新 */
    function update() {

        stats.update();

        controls.update();

        if (box1 && box2) {

            box1.rotateY(0.01);
            box2.rotateY(0.01);

        }

    }

    /* 初始化 */
    function init() {

        if (!Detector.webgl) Detector.addGetWebGLMessage();

        initScene();
        initCamera();
        initRender();
        initLight();
        initControls();
        initContent();
        initGui();
        /* 监听事件 */
        window.addEventListener('resize', onWindowResize, false);

    }

    /* 循环渲染 */
    function animate() {

        requestAnimationFrame(animate);
        renderer.render(scene, camera);
        update();

    }

    /* 初始加载 */
    (function () {
        console.log("three init start...");

        init();
        animate();

        console.log("three init end...");
    })();

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