<!DOCTYPE html>
<html lang="en">
<head>
    <meta name="renderer" content="webkit"/>
    <meta name="force-rendering" content="webkit"/>
    <meta charset="UTF-8">
    <title>Title</title>
    <style type="text/css">
        html, body {
            margin: 0;
            height: 100%;
            background-size: cover;
            background-position: center center;
            overflow: hidden;
        }
    </style>
</head>
<body onload="draw();" style="background-image: url(https://jllsly.com/wallpapers/snow-night-wallpapers-high-quality-resolution-Is-Cool-Wallpapers-1.jpg);">
</body>
<script src="https://johnson2heng.github.io/three.js-demo/lib/three.js"></script>
<script src="https://johnson2heng.github.io/three.js-demo/lib/js/controls/OrbitControls.js"></script>
<script src="https://johnson2heng.github.io/three.js-demo/lib/js/libs/stats.min.js"></script>
<script src="https://johnson2heng.github.io/three.js-demo/lib/js/libs/dat.gui.min.js"></script>
<script src="https://cdn.bootcss.com/lodash.js/4.17.11/lodash.min.js"></script>
<script src="//cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdn.bootcss.com/gsap/latest/TweenMax.min.js"></script>
<script>

    //https://www.overdriveonline.com/wp-content/uploads/sites/8/2013/01/Truck-at-night-in-snow.jpg
    //https://ateachinglifedotcom.files.wordpress.com/2016/12/snow-at-night.jpg
    //https://d2v9y0dukr6mq2.cloudfront.net/video/thumbnail/H0MA-uKSipsekm5s/magical-winter-night-in-the-snow-covered-pine-forest-realistic-3d-animation_bcgk90me1g_thumbnail-full01.png
    //https://i.pinimg.com/originals/18/03/c9/1803c9683d2a6acb5f827114015a51c8.jpg
    //https://travelingorion.files.wordpress.com/2017/02/img_6666.jpg
    //https://jllsly.com/wallpapers/snow-night-wallpaper-desktop-Is-Cool-Wallpapers-1.jpg
    //https://juegosrev.com/wp-content/uploads/2017/06/Winter-Night-Wallpapers-Gallery-88-Plus-PIC-WPW504471.jpg
    //https://jllsly.com/wallpapers/snow-night-wallpapers-high-quality-resolution-Is-Cool-Wallpapers-1.jpg
    setInterval(function(){
        if (location.hash.length > 2) {
            document.body.style.backgroundImage = "url("+ location.hash.substr(1) + ")";
        }
    }, 1000)

    var renderer, camera;
    var swidth,sheight, swidth_2;

    var rotateRatio = 0.04;

    var wind = {x:0, z:0, y:0, ratio:0.45};

    let windChangeStep = function(key){
        TweenMax.to(
            wind,
            _.random(1.6, 2.5, true),
            {
                [key]:_.random(-1, 1, true) * wind.ratio,
                ease: Power2.easeInOut,
                onComplete:function(){
                    windChangeStep(key)
                }
            }
        )
    }

    windChangeStep("x");
    windChangeStep("z");
    windChangeStep("y");
    var getVelocity = function(){
        return {
            y:_.random(-0.2, -0.05, true) * 1.4,
            x:_.random(-0.1, 0.2, true) * 0.01,
            z:_.random(-0.1, 0.2, true) * 0.01,
            angle:_.random(-Math.PI/2, Math.PI/2, true)
        }
    }


    function clacSize(){
        swidth = window.innerWidth * 0.05;
        sheight = window.innerHeight * 0.05;
        swidth_2 = swidth * swidth;
    }


    $(window).on("resize", e=>{
        _.throttle(e=>{
            clacSize();
        }, 300)
    });
    clacSize();

    $(document).on("mousemove", e=>{
        let {screenX, screenY} = e;
        // wind.x = (screenX - innerWidth * 0.5)/innerWidth/2 * 1.2;
        // wind.z = (screenY - innerHeight * 0.5)/innerHeight/2 * 1.2;
    });


    function initRender() {
        renderer = new THREE.WebGLRenderer({antialias: true, alpha:true});
        // renderer.setClearColor(new THREE.Color(0x222222)); //设置背景颜色
        renderer.setClearColor(0x000000, 0.2); //设置背景颜色
        renderer.setSize(window.innerWidth, window.innerHeight);
        document.body.appendChild(renderer.domElement);
    }


    function initCamera() {
        camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 12, swidth * 2);
        camera.position.set(0, 0, swidth * 0.75);
        camera.lookAt(new THREE.Vector3(0, 30, 0));
    }


    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);
        // controls = new THREE.TrackballControls(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": 0.9,
            "transparent": true,
            "opacity": 1,
            "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("/static/img/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,
            transparent,
            opacity,
            vertexColors,
            sizeAttenuation,
            color,
            depthTest: false,  //设置解决透明度有问题的情况
            map: texture,
        });

        for (var i = 0; i < 16000; i++) {
            //添加顶点的坐标
            var particle = new THREE.Vector3(0,0,0);

            resetParticle(particle);

            var v = getVelocity();

            particle.velocityY = v.y;
            particle.velocityX = v.x;
            particle.velocityZ = v.z;
            particle.ang =       v.angle;

            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 resetParticle(particle){
        particle.y = _.random(-sheight, sheight, true);
        particle.x = _.random(-swidth, swidth , true);
        particle.z = _.random(-swidth, swidth , true);
    }

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

        vertices.forEach(function (v, i) {
            v.ang+=0.05;

            let a = Math.atan(v.z/v.x);
            if(v.x<0){
                a = a + Math.PI;
            }
            let r = Math.pow(v.x*v.x + v.z*v.z, 0.5);
            a = a + rotateRatio * Math.pow(1 - r/swidth, 3);

            //漩涡
            v.x = Math.cos(a) * r;
            v.z = Math.sin(a) * r;

            //速度
            v.y = v.y + v.velocityY;
            v.x = v.x + v.velocityX + Math.cos(v.ang) * 0.09 ;
            v.z = v.z + v.velocityZ + Math.sin(v.ang) * 0.09 ;

            //风
            v.y = v.y + wind.y * 0.5;
            v.x = v.x + wind.x;
            v.z = v.z + wind.z;

            if (v.y <= -sheight){
                v.y = sheight;
            }else if (v.x < -swidth) {
                v.x = swidth
            }else if (v.x > swidth) {
                v.x = -swidth;
            }else if (v.z < -swidth) {
                v.z = swidth
            }else if (v.z > swidth) {
                v.z = -swidth;
            }
        });

        //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>