31 Three.js的特殊光源镜头光晕（lens flare）

时间：2022-01-26 04:55:42

简介

当你直接朝着太阳或者一个非常明亮的灯光的时候就会出现镜头光晕效果。大多数情况会避免这种效果，但是如果对于游戏或者三维图形来说，它提供了一种很好的效果，让场景看上去更加真实。

创建镜头光晕方法

var lensFlare =new THREE.LensFlare( texture, size, distance, blending, color );

实例化相关参数

参数 描述
texture (可选) THREE.Texture 纹理用来决定光晕的形状及样式
size (可选) 尺寸（以像素为单位） (如果将它指定为-1，将使用纹理本身的尺寸)
distance (可选)从光源（0）到摄像机（1），将光晕放置在正确的位置
blending (可选) 混合模式，光晕默认是THREE.NormalBlending
color (可选) 光晕的颜色

实例化对象的相关属性和方法

属性

.isLensFlare

是否是一个光晕对象，默认返回ture

.lensFlares

通过修改相关的对象来修改实例化函数时的相关传值。

{
texture: texture,   // texture passed in the constructor or add method
size: size,         // if not passed in, default is -1
distance: distance,     // if not passed in, default is 0
x: 0, y: 0, z: 0,   // screen position (-1 => 1) z = 0 is in front z = 1 is back
scale: 1,
rotation: 0,
opacity: opacity,   // if not passed in, default is 1
color: color,       // if not passed in, default is new Color( 0xffffff ) (white)
blending: blending  // if not passed in, default is NormalBlending
}

.positionScreen

返回在场景中的位置

.customUpdateCallback

自定义的更新回调函数，赋值一个function，默认是undefined，通过updateLensFlares()调用。

对象方法

.add ( texture, size, distance, blending, color )

添加一个光晕，和构造函数的配置一样

.clone ()

克隆一个对象

.copy ( source )

复制目标source的参数，进行配置

.updateLensFlares ()

LensFlares基于positionscreen属性更新。
可以通过设置customupdatecallback函数重写。

简单实现案例

首先，需要把渲染器的alpha设置为true，如果不设置，光晕效果将无法出现。

renderer = new THREE.WebGLRenderer({antialias: true, alpha: true});

然后先加载光晕所需要的纹理，比如：

        var textureLoader = new THREE.TextureLoader();

var textureFlare0 = textureLoader.load("examples/textures/lensflare/lensflare0.png");

然后，实例化光晕对象，并把所需的要的光晕的对象添加进去。

        var flareColor = new THREE.Color(0xffffff);
        flareColor.setHSL(0.55, 0.9, 1.0);

        var lensFlare = new THREE.LensFlare( textureFlare0, 500, 0.0, THREE.AdditiveBlending, flareColor );

        lensFlare.add( textureFlare2, 512, 0.0, THREE.AdditiveBlending );
        lensFlare.add( textureFlare2, 512, 0.0, THREE.AdditiveBlending );
        lensFlare.add( textureFlare2, 512, 0.0, THREE.AdditiveBlending );

        lensFlare.add( textureFlare3, 60, 0.6, THREE.AdditiveBlending );
        lensFlare.add( textureFlare3, 70, 0.7, THREE.AdditiveBlending );
        lensFlare.add( textureFlare3, 120, 0.9, THREE.AdditiveBlending );
        lensFlare.add( textureFlare3, 70, 1.0, THREE.AdditiveBlending );

        lensFlare.position.copy(pointLight.position);

最后，把光晕对象添加到场景当中。

scene.add(lensFlare);

案例代码

效果截图，动图质量差点，凑合着看吧。
31 Three.js的特殊光源镜头光晕（lens flare）

全部代码

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style type="text/css">
html, body {
margin: 0;
height: 100%;
}

canvas {
display: block;
}

</style>
</head>
<body onload="draw();">

</body>
<script src="build/three.js"></script>
<script src="examples/js/controls/FlyControls.js"></script>
<script src="examples/js/libs/stats.min.js"></script>
<script src="examples/js/libs/dat.gui.min.js"></script>
<script>
var renderer;
function initRender() {

 renderer = new THREE.WebGLRenderer({antialias: true, alpha: true});
 renderer.setSize(window.innerWidth, window.innerHeight);
//告诉渲染器需要阴影效果
 renderer.shadowMap.enabled = true;
 renderer.shadowMap.type = THREE.PCFSoftShadowMap; // 默认的是，没有设置的这个清晰 THREE.PCFShadowMap
 renderer.setClearColor(0x111111);
 renderer.gammaInput = true;
 renderer.gammaOutput = true;
 document.body.appendChild(renderer.domElement);
 }

var camera;
function initCamera() {
 camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);
 camera.position.set(0, 40, 0);
 }

var scene;
function initScene() {
 scene = new THREE.Scene();
 }

var ambientLight,pointLight;
function initLight() {
 ambientLight = new THREE.AmbientLight("#111111");
 scene.add(ambientLight);

 pointLight = new THREE.PointLight("#ffffff");
 pointLight.position.set(-400, 600, -100);

//告诉平行光需要开启阴影投射
 pointLight.castShadow = true;

 scene.add(pointLight);

// 添加 lens flares
var textureLoader = new THREE.TextureLoader();

var textureFlare0 = textureLoader.load("examples/textures/lensflare/lensflare0.png");
var textureFlare2 = textureLoader.load("examples/textures/lensflare/lensflare2.png");
var textureFlare3 = textureLoader.load("examples/textures/lensflare/lensflare3.png");

var flareColor = new THREE.Color(0xffffff);
 flareColor.setHSL(0.55, 0.9, 1.0);

var lensFlare = new THREE.LensFlare( textureFlare0, 500, 0.0, THREE.AdditiveBlending, flareColor );

 lensFlare.add( textureFlare2, 512, 0.0, THREE.AdditiveBlending );
 lensFlare.add( textureFlare2, 512, 0.0, THREE.AdditiveBlending );
 lensFlare.add( textureFlare2, 512, 0.0, THREE.AdditiveBlending );

 lensFlare.add( textureFlare3, 60, 0.6, THREE.AdditiveBlending );
 lensFlare.add( textureFlare3, 70, 0.7, THREE.AdditiveBlending );
 lensFlare.add( textureFlare3, 120, 0.9, THREE.AdditiveBlending );
 lensFlare.add( textureFlare3, 70, 1.0, THREE.AdditiveBlending );

 lensFlare.position.copy(pointLight.position);

 scene.add(lensFlare);
 }


var cube,plane;
function initModel() {

//辅助工具
var helper = new THREE.AxisHelper(10);
 scene.add(helper);

//球体
var sphereGeometry = new THREE.SphereGeometry(10,30,30);
var sphereMaterial = new THREE.MeshStandardMaterial({color:0xff00ff});
var sphere = new THREE.Mesh(sphereGeometry,sphereMaterial);
 sphere.position.set(-20,20,0);

 sphere.castShadow = true;

 scene.add(sphere);

//立方体
var cubeGeometry = new THREE.CubeGeometry(10,10,10);

var cubeMaterial = new THREE.MeshLambertMaterial({color: 0x00ffff});

 cube = new THREE.Mesh(cubeGeometry, cubeMaterial);
 cube.position.x = 30;
 cube.position.y = 5;
 cube.position.z = -5;

//告诉立方体需要投射阴影
 cube.castShadow = true;

 scene.add(cube);

//底部平面
var planeGeometry = new THREE.PlaneGeometry(5000, 5000, 20, 20);
var planeMaterial = new THREE.MeshStandardMaterial({color: 0xaaaaaa});

 plane = new THREE.Mesh(planeGeometry, planeMaterial);
 plane.rotation.x = -0.5 * Math.PI;
 plane.position.y = -0;

//告诉底部平面需要接收阴影
 plane.receiveShadow = true;

 scene.add(plane);

 }

//初始化性能插件
var stats;
function initStats() {
 stats = new Stats();
 document.body.appendChild(stats.dom);
 }

//用户交互插件 鼠标左键按住旋转，右键按住平移，滚轮缩放
var controls,clock;
function initControls() {

 clock = new THREE.Clock();

 controls = new THREE.FlyControls( camera );

 controls.movementSpeed = 100; //设置移动的速度
 controls.rollSpeed = Math.PI / 6; //设置旋转速度
 controls.autoForward = false;
 controls.dragToLook = false;
 }


//初始化dat.GUI简化试验流程
var param;
function initGui() {

 }

function render() {
 renderer.render(scene, camera);

var delta = clock.getDelta();

//更新性能插件
 stats.update();

 controls.update(delta);
 }

//窗口变动触发的函数
function onWindowResize() {

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

 }

function animate() {

//更新控制器
 render();

 requestAnimationFrame(animate);
 }

function draw() {
 initRender();
 initScene();
 initCamera();
 initLight();
 initModel();
 initControls();
 initStats();
 initGui();

 animate();
 window.onresize = onWindowResize;
 }
</script>
</html>
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