<!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="/lib/three.js"></script>
<script src="/lib/js/controls/OrbitControls.js"></script>
<script src="/lib/js/libs/stats.min.js"></script>
<script src="/lib/js/libs/dat.gui.min.js"></script>
<script>
    var renderer;

    function initRender() {
        renderer = new THREE.WebGLRenderer({antialias: true});
        renderer.setClearColor(new THREE.Color(0xffffff)); //设置背景颜色
        renderer.setSize(window.innerWidth, window.innerHeight);
        document.body.appendChild(renderer.domElement);
    }

    var camera;

    function initCamera() {
        camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 1, 200);
        camera.position.set(0, 20, 100);
        camera.lookAt(new THREE.Vector3(0, 30, 0));
    }

    var scene;

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

    var light;

    function initLight() {
        scene.add(new THREE.AmbientLight(0x404040));

        light = new THREE.DirectionalLight(0xffffff);
        light.position.set(1, 1, 1);
        scene.add(light);
    }


    function initModel() {

        //轴辅助 （每一个轴的长度）
        var object = new THREE.AxesHelper(500);
        //scene.add(object);

    }

    //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远距离
        controls.minDistance = 20;
        //设置相机距离原点的最远距离
        controls.maxDistance = 10000;
        //是否开启右键拖拽
        controls.enablePan = true;
    }

    //生成gui设置配置项
    var gui;

    var cloud;
    function initGui() {
        //声明一个保存需求修改的相关数据的对象
        gui = {
            "size": 2,
            "transparent": true,
            "opacity": 0.6,
            "vertexColors": true,
            "color": 0xffffff,
            "sizeAttenuation": true,
            "rotateSystem": false,
            redraw: function () {
                if (cloud) {
                    scene.remove(cloud);
                }
                createParticles(gui.size, gui.transparent, gui.opacity, gui.vertexColors, gui.sizeAttenuation, gui.color);
                //设置是否自动旋转
                controls.autoRotate = gui.rotateSystem;
            }
        };
        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）gui.add(controls, 'size', 0, 10).onChange(controls.redraw);
        datGui.add(gui, 'size',0.1,10).onChange(gui.redraw);
        datGui.add(gui, 'transparent').onChange(gui.redraw);
        datGui.add(gui, 'opacity', 0, 1).onChange(gui.redraw);
        datGui.add(gui, 'vertexColors').onChange(gui.redraw);
        datGui.addColor(gui, 'color').onChange(gui.redraw);
        datGui.add(gui, 'sizeAttenuation').onChange(gui.redraw);
        datGui.add(gui, 'rotateSystem').onChange(gui.redraw);

        gui.redraw();
    }

    //生成粒子的方法
    function createParticles(size, transparent, opacity, vertexColors, sizeAttenuation, color) {
        var texture = new THREE.TextureLoader().load("/lib/textures/snow.png");
        //存放粒子数据的网格
        var geom = new THREE.Geometry();
        //样式化粒子的THREE.PointCloudMaterial材质
        var material = new THREE.PointsMaterial({
            size: size,
            transparent: transparent,
            opacity: opacity,
            vertexColors: vertexColors,
            sizeAttenuation: sizeAttenuation,
            color: color,
            map:texture,
            depthTest: false  //设置解决透明度有问题的情况
        });


        var range = 120;
        for (var i = 0; i < 15000; i++) {
            //添加顶点的坐标
            var particle = new THREE.Vector3(Math.random() * range - range / 2, Math.random() * range - range / 2, Math.random() * range - range / 2);
            particle.velocityY = 0.1 + Math.random() / 5;
            particle.velocityX = (Math.random() - 0.5) / 3;
            geom.vertices.push(particle);
            var color = new THREE.Color(0xffffff);
            //.setHSL ( h, s, l ) h — 色调值在0.0和1.0之间 s — 饱和值在0.0和1.0之间 l — 亮度值在0.0和1.0之间。 使用HSL设置颜色。
            //随机当前每个粒子的亮度
            //color.setHSL(color.getHSL().h, color.getHSL().s, Math.random() * color.getHSL().l);
            geom.colors.push(color);
        }

        //生成模型，添加到场景当中
        cloud = new THREE.Points(geom, material);
        cloud.verticesNeedUpdate = true;

        scene.add(cloud);
    }

    function render() {

        //产生雨滴动画效果
        var vertices = cloud.geometry.vertices;
        vertices.forEach(function (v) {

            v.y = v.y - (v.velocityY);
            v.x = v.x - (v.velocityX)*.5;

            if (v.y <= -60) v.y = 60;
            if (v.x <= -20 || v.x >= 20) v.velocityX = v.velocityX * -1;
        });

        //设置实时更新网格的顶点信息
        cloud.geometry.verticesNeedUpdate = true;

        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
        controls.update();
        render();

        //更新性能插件
        stats.update();
        requestAnimationFrame(animate);
    }

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

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