var renderer;
function initRender() {
	renderer = new THREE.WebGLRenderer({antialias: 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
	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, 100);
	camera.lookAt(new THREE.Vector3(0, 0, 0));
}

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

//初始化dat.GUI简化试验流程
var gui;
function initGui() {
	//声明一个保存需求修改的相关数据的对象
	gui = {
		directionalLight:"#ffffff", //点光源
		directionalLightIntensity:1, //灯光强度
		visible:true, //是否可见
		castShadow:true,
		exponent:30,
		target:"plane",
		debug:false,
		groundColor:"#00ff00",
		skyColor:"#0000ff",
		hemiLightIntensity:0.3
	};
	var datGui = new dat.GUI();
	//将设置属性添加到gui当中，gui.add(对象，属性，最小值，最大值）

	datGui.addColor(gui,"skyColor").onChange(function (e) {
		ambientLight.color = new THREE.Color(e);  //--环境光会和平行光的颜色混合
	});
	datGui.addColor(gui,"groundColor").onChange(function (e) {
		ambientLight.groundColor = new THREE.Color(e);  //--这个字段未生效，api中查不到
	});
	datGui.add(gui,"hemiLightIntensity",0,1).onChange(function (e) {
		ambientLight.intensity = e;   //--intensity表示强度
	});
	datGui.addColor(gui,"directionalLight").onChange(function (e) {
		directionalLight.color = new THREE.Color(e);  
	});
	datGui.add(gui,"directionalLightIntensity",0,5).onChange(function (e) {
		directionalLight.intensity = e;
	});
	datGui.add(gui,"visible").onChange(function (e) {
		directionalLight.visible = e;
	});
	datGui.add(gui,"castShadow").onChange(function (e) {
		directionalLight.castShadow = e;
	});
	datGui.add(gui,"debug").onChange(function (e) {
		if(e){
			var debug = new THREE.CameraHelper(directionalLight.shadow.camera);
			debug.name = "debug";
			scene.add(debug);
		}
		else{
			var debug = scene.getObjectByName("debug");
			scene.remove(debug);
		}
	});
}

var ambientLight,directionalLight;
function initLight() {

	ambientLight = new THREE.AmbientLight("#111111");
	scene.add(ambientLight);

	directionalLight = new THREE.DirectionalLight("#ffffff");
	directionalLight.position.set(-40, 60, -10);

	//--根据官网： shadow.camera用来控制物体在其他物体上产生的阴影
	directionalLight.shadow.camera.near = 20; //产生阴影的最近距离
	directionalLight.shadow.camera.far = 200; //产生阴影的最远距离
	directionalLight.shadow.camera.left = -50; //产生阴影距离位置的最左边位置
	directionalLight.shadow.camera.right = 50; //最右边
	directionalLight.shadow.camera.top = 50; //最上边
	directionalLight.shadow.camera.bottom = -50; //最下面

	//这两个值决定使用多少像素生成阴影 默认512
	directionalLight.shadow.mapSize.height = 1024;  //--这两个值更好，会产生更好的阴影效果，但会有更多的计算。
	directionalLight.shadow.mapSize.width = 1024;

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

	scene.add(directionalLight);
}

var cube,plane;
function initModel() {

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

	//球体
	var sphereGeometry = new THREE.SphereGeometry(10,30,30);
	var sphereMaterial = new THREE.MeshLambertMaterial({color:0xeeeeee});
	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.MeshLambertMaterial({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;
function initControls() {

	controls = new THREE.OrbitControls(camera, renderer.domElement);

	// 如果使用animate方法时，将此函数删除
	//controls.addEventListener( 'change', render );
	// 使动画循环使用时阻尼或自转 意思是否有惯性
	controls.enableDamping = true;
	//动态阻尼系数 就是鼠标拖拽旋转灵敏度
	//controls.dampingFactor = 0.25;
	//是否可以缩放
	controls.enableZoom = true;
	//是否自动旋转
	controls.autoRotate = false;
	//设置相机距离原点的最近距离
	controls.minDistance = 50;
	//设置相机距离原点的最远距离
	controls.maxDistance = 200;
	//是否开启右键拖拽
	controls.enablePan = true;
}

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

//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();

	//更新性能插件
	stats.update();

	controls.update();

	requestAnimationFrame(animate);
}

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

	animate();
	window.onresize = onWindowResize;
}

draw();