<!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/utils/SceneUtils.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(0x000000)); //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, 0.1, 200);
        camera.position.set(0, 0, 50);
    }

    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);
    }

    //生成gui设置配置项
    var controls,knot;
    function initGui() {
        //声明一个保存需求修改的相关数据的对象
        controls = {
            "radius": 13,
            "tube": 1.7,
            "radialSegments": 156,
            "tubularSegments": 12,
            "p": 3,
            "q": 4,
            "heightScale": 3.5,
            "asParticles": false,
            "rotate": false,
            redraw: function () {
                // 删除掉原有的模型
                if (knot) scene.remove(knot);
                // 创建一个环形结构
                ///<param name ="radius" type="float">环形结半径</param>
                ///<param name ="tube" type="float">环形结弯管半径</param>
                ///<param name ="radialSegments" type="int">环形结圆周上细分线段数</param>
                ///<param name ="tubularSegments" type="int">环形结弯管圆周上的细分线段数</param>
                ///<param name ="p" type="float">p\Q:对knot(节)状方式有效,控制曲线路径缠绕的圈数,P决定垂直方向的参数.</param>
                ///<param name ="q" type="float">p\Q:对knot(节)状方式有效,控制曲线路径缠绕的圈数,Q决定水平方向的参数.</param>
                ///<param name ="heightScale" type="float">环形结高方向上的缩放.默认值是1</param>
                var geom = new THREE.TorusKnotGeometry(controls.radius, controls.tube, Math.round(controls.radialSegments), Math.round(controls.tubularSegments), Math.round(controls.p), Math.round(controls.q), controls.heightScale);

                //判断绘制的模型
                if (controls.asParticles) {
                    knot = createPointCloud(geom);
                } else {
                    knot = createMesh(geom);
                }

                // 将新创建的模型添加进去
                scene.add(knot);
            }
        };
        var gui = 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);
        gui.add(controls, 'radius', 0, 40).onChange(controls.redraw);
        gui.add(controls, 'tube', 0, 40).onChange(controls.redraw);
        gui.add(controls, 'radialSegments', 0, 400).step(1).onChange(controls.redraw);
        gui.add(controls, 'tubularSegments', 1, 20).step(1).onChange(controls.redraw);
        gui.add(controls, 'p', 1, 10).step(1).onChange(controls.redraw);
        gui.add(controls, 'q', 1, 15).step(1).onChange(controls.redraw);
        gui.add(controls, 'heightScale', 0, 5).onChange(controls.redraw);
        gui.add(controls, 'asParticles').onChange(controls.redraw);
        gui.add(controls, 'rotate').onChange(controls.redraw);

        controls.redraw();
    }


    var step = 0;
    function render() {

        stats.update();

        if (controls.rotate) {
            knot.rotation.y = step += 0.01;
        }

        renderer.render(scene, camera);
    }

    // 使用canvas创建纹理
    function generateSprite() {

        var canvas = document.createElement('canvas');
        canvas.width = 16;
        canvas.height = 16;

        var context = canvas.getContext('2d');
        var gradient = context.createRadialGradient(canvas.width / 2, canvas.height / 2, 0, canvas.width / 2, canvas.height / 2, canvas.width / 2);
        gradient.addColorStop(0, 'rgba(255,255,255,1)');
        gradient.addColorStop(0.2, 'rgba(0,255,255,1)');
        gradient.addColorStop(0.4, 'rgba(0,0,64,1)');
        gradient.addColorStop(1, 'rgba(0,0,0,1)');

        context.fillStyle = gradient;
        context.fillRect(0, 0, canvas.width, canvas.height);

        var texture = new THREE.Texture(canvas);
        texture.needsUpdate = true;
        return texture;

    }

    // 创建粒子系统
    function createPointCloud(geom) {
        var material = new THREE.PointCloudMaterial({
            color: 0xffffff,
            size: 3,
            transparent: true,
            blending: THREE.AdditiveBlending,
            map: generateSprite(),
            depthTest: false
        });

        var cloud = new THREE.Points(geom, material);
        cloud.sortParticles = true;
        return cloud;
    }

    //创建模型
    function createMesh(geom) {

        // 创建两面都显示的纹理
        var meshMaterial = new THREE.MeshNormalMaterial({});
        meshMaterial.side = THREE.DoubleSide;

        // 生成模型
        var mesh = THREE.SceneUtils.createMultiMaterialObject(geom, [meshMaterial]);

        return mesh;
    }

    //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() {
        render();

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

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

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