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博主的案例並不難，只是爲了更好的給想入門threeJS的同學一點點經驗！！！！！
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涉及的知識點博主已經從three源碼庫裏面摘要出來放在對應的註釋裏面
今天學習Helper裏面的RectAreaLightHelper助手！
順便加入了鼠標控制相機的組件OrbitControls，不懂可以先忽略！
效果圖：
代碼：
<html>
<head>
<title>threeJS-Helper12-RectAreaLightHelper(矩形區域光助手)</title>
<style>
body {
background-color: #000;
margin: 0px;
overflow: hidden;
}
canvas {
width: 100%;
height: 100%
}
</style>
</head>
<body>
<script src="../../../build/three.js"></script>
<script src="../../js/lights/RectAreaLightUniformsLib.js"></script>
<script src="../../js/controls/OrbitControls.js"></script>
<script>
var camera, scene, renderer, geometry, material, animate, controls; //常用變量
var cube, light, helper, rectLight; //自定義對象變量
var target = new THREE.Vector3(0, 0, 0);
init();
animate();
function init() {
scene = new THREE.Scene();
scene.background = new THREE.Color(0xcfcfcf);
camera = new THREE.PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);
camera.position.set(0, 50, 150);
camera.lookAt(target);
camera.updateProjectionMatrix(); //相機更新
var ambient = new THREE.AmbientLight(0xffffff, 0.1);
scene.add(ambient);
// RectAreaLight( color：顏色, intensity：強度, width：寬, height：高 )
rectLight = new THREE.RectAreaLight(0xcfcfcf, 1, 100, 100);
rectLight.position.set(30, 50, -30);
scene.add(rectLight);
//這裏設置2個平面，來顯示區域光
var rectLightMesh = new THREE.Mesh(new THREE.PlaneBufferGeometry(), new THREE.MeshBasicMaterial({
//這裏可以設置區域光片面材質的屬性
}
));
rectLightMesh.scale.x = rectLight.width;
rectLightMesh.scale.y = rectLight.height;
rectLight.add(rectLightMesh);
var rectLightMeshBack = new THREE.Mesh(new THREE.PlaneBufferGeometry(), new THREE.MeshBasicMaterial({
color: 0xcfcfff
}));
rectLightMeshBack.rotation.y = Math.PI;
rectLightMesh.add(rectLightMeshBack);
// PolarGridHelper( radius：標網格的半徑, radials：徑向線的數量, circles：圓圈數,
// divisions：每個圓圈使用的線段數, color1：用於網格元素的第一種顏色, color2：用於網格元素的第一種顏色 )
var radius = 100;
var radials = 16;
var circles = 8;
var divisions = 64;
var PolarGridHelper = new THREE.PolarGridHelper(radius, radials, circles, divisions);
PolarGridHelper.position.set(0, -20, 0)
scene.add(PolarGridHelper)
renderer = new THREE.WebGLRenderer({
antialias: true
});
renderer.setPixelRatio(window.devicePixelRatio);
renderer.setSize(window.innerWidth, window.innerHeight);
renderer.shadowMap.enabled = true;
renderer.shadowMap.type = THREE.PCFSoftShadowMap;
renderer.gammaInput = true;
renderer.gammaOutput = true;
document.body.appendChild(renderer.domElement);
//OrbitControls控件操作模塊
controls = new THREE.OrbitControls(camera, renderer.domElement);
controls.addEventListener('change', function () {
renderer.render(scene, camera);
});
// BoxGeometry( width, height, depth, widthSegments, heightSegments, depthSegments )
geometry = new THREE.BoxGeometry(30, 30, 30, 3, 3, 3);
material = new THREE.MeshStandardMaterial({
color: 0xcfcfcf,
wireframe: false,
castShadow: true,
receiveShadow: true,
roughness: 0, //表面放射粗糙度
metalness: 0 //金屬感
}); //wireframe默認爲false
cube = new THREE.Mesh(geometry, material);
cube.position.x=20;
scene.add(cube);
var matStdObjects = new THREE.MeshStandardMaterial( { color: 0xA0cf00, roughness: 0, metalness: 0.6 } );
var mshStdBox = new THREE.Mesh( geometry, matStdObjects );
mshStdBox.position.set(-30, 0, 20 );
mshStdBox.rotation.set( 0, Math.PI / 2.0, 0 );
mshStdBox.castShadow = true;
mshStdBox.receiveShadow = true;
scene.add( mshStdBox );
}
function animate() {
requestAnimationFrame(animate);
controls.update();
var t = (Date.now() / 2000);
var r = 25.0;
var lx = r * Math.cos(t);
rectLight.position.set(lx, rectLight.position.y, rectLight.position.z);
rectLight.lookAt(target);
cube.rotation.y += 0.01;
renderer.render(scene, camera);
};
</script>
</body>
</html>