// once everything is loaded, we run our Three.js stuff.
    function init() {

        var stats = initStats();

        // create a scene, that will hold all our elements such as objects, cameras and lights.
        var scene = new THREE.Scene();
        scene.fog = new THREE.Fog(0xaaaaaa, 0.010, 200);

        // create a camera, which defines where we're looking at.
        var camera = new THREE.PerspectiveCamera(45, window.innerWidth / window.innerHeight, 0.1, 1000);


        // create a render and set the size
        var renderer = new THREE.WebGLRenderer({antialias: true, alpha: true});

        renderer.setClearColor(new THREE.Color(0xaaaaff, 1.0));
        renderer.setSize(window.innerWidth, window.innerHeight);
        renderer.shadowMapEnabled = true;


        // create the ground plane
        var textureGrass = THREE.ImageUtils.loadTexture("../assets/textures/ground/grasslight-big.jpg");
        textureGrass.wrapS = THREE.RepeatWrapping;
        textureGrass.wrapT = THREE.RepeatWrapping;
        textureGrass.repeat.set(4, 4);


        var planeGeometry = new THREE.PlaneGeometry(1000, 200, 20, 20);
        var planeMaterial = new THREE.MeshLambertMaterial({map: textureGrass});
        var plane = new THREE.Mesh(planeGeometry, planeMaterial);
        plane.receiveShadow = true;

        // rotate and position the plane
        plane.rotation.x = -0.5 * Math.PI;
        plane.position.x = 15;
        plane.position.y = 0;
        plane.position.z = 0;

        // add the plane to the scene
        scene.add(plane);

        // create a cube
        var cubeGeometry = new THREE.BoxGeometry(4, 4, 4);
        var cubeMaterial = new THREE.MeshLambertMaterial({color: 0xff3333});
        var cube = new THREE.Mesh(cubeGeometry, cubeMaterial);
        cube.castShadow = true;

        // position the cube
        cube.position.x = -4;
        cube.position.y = 3;
        cube.position.z = 0;

        // add the cube to the scene
        scene.add(cube);

        var sphereGeometry = new THREE.SphereGeometry(4, 25, 25);
        var sphereMaterial = new THREE.MeshLambertMaterial({color: 0x7777ff});
        var sphere = new THREE.Mesh(sphereGeometry, sphereMaterial);

        // position the sphere
        sphere.position.x = 10;
        sphere.position.y = 5;
        sphere.position.z = 10;
        sphere.castShadow = true;

        // add the sphere to the scene
        scene.add(sphere);

        // position and point the camera to the center of the scene
        camera.position.x = -20;
        camera.position.y = 15;
        camera.position.z = 45;
        camera.lookAt(new THREE.Vector3(10, 0, 0));

        // add subtle ambient lighting
        var ambiColor = "#1c1c1c";
        var ambientLight = new THREE.AmbientLight(ambiColor);
        scene.add(ambientLight);

        // add spotlight for a bit of light
        var spotLight0 = new THREE.SpotLight(0xcccccc);
        spotLight0.position.set(-40, 60, -10);
        spotLight0.lookAt(plane);
        scene.add(spotLight0);


        var target = new THREE.Object3D();
        target.position = new THREE.Vector3(5, 0, 0);

        var pointColor = "#ffffff";
//    var spotLight = new THREE.SpotLight( pointColor);
        var spotLight = new THREE.DirectionalLight(pointColor);
        spotLight.position.set(30, 10, -50);
        spotLight.castShadow = true;
        spotLight.shadowCameraNear = 0.1;
        spotLight.shadowCameraFar = 100;
        spotLight.shadowCameraFov = 50;
        spotLight.target = plane;
        spotLight.distance = 0;
        spotLight.shadowCameraNear = 2;
        spotLight.shadowCameraFar = 200;
        spotLight.shadowCameraLeft = -100;
        spotLight.shadowCameraRight = 100;
        spotLight.shadowCameraTop = 100;
        spotLight.shadowCameraBottom = -100;
        spotLight.shadowMapWidth = 2048;
        spotLight.shadowMapHeight = 2048;


        scene.add(spotLight);


        // add the output of the renderer to the html element
        document.getElementById("WebGL-output").appendChild(renderer.domElement);

        // call the render function
        var step = 0;

        // used to determine the switch point for the light animation
        var invert = 1;
        var phase = 0;

        var controls = new function () {
            this.rotationSpeed = 0.03;
            this.bouncingSpeed = 0.03;
            this.ambientColor = ambiColor;
            this.pointColor = pointColor;
            this.intensity = 0.1;
            this.distance = 0;
            this.exponent = 30;
            this.angle = 0.1;
            this.debug = false;
            this.castShadow = true;
            this.onlyShadow = false;
            this.target = "Plane";

        };

        var gui = new dat.GUI();
        gui.addColor(controls, 'ambientColor').onChange(function (e) {
            ambientLight.color = new THREE.Color(e);
        });

        gui.addColor(controls, 'pointColor').onChange(function (e) {
            spotLight.color = new THREE.Color(e);
        });

        gui.add(controls, 'intensity', 0, 5).onChange(function (e) {
            spotLight.intensity = e;
        });


        var textureFlare0 = THREE.ImageUtils.loadTexture("../assets/textures/lensflare/lensflare0.png");
        var textureFlare3 = THREE.ImageUtils.loadTexture("../assets/textures/lensflare/lensflare3.png");

        var flareColor = new THREE.Color(0xffaacc);
        var lensFlare = new THREE.LensFlare(textureFlare0, 350, 0.0, THREE.AdditiveBlending, flareColor);

        lensFlare.add(textureFlare3, 60, 0.6, THREE.AdditiveBlending);
        lensFlare.add(textureFlare3, 70, 0.7, THREE.AdditiveBlending);
        lensFlare.add(textureFlare3, 120, 0.9, THREE.AdditiveBlending);
        lensFlare.add(textureFlare3, 70, 1.0, THREE.AdditiveBlending);

        lensFlare.position.copy(spotLight.position);
        scene.add(lensFlare);

        render();

        function render() {
            stats.update();
            // rotate the cube around its axes
            cube.rotation.x += controls.rotationSpeed;
            cube.rotation.y += controls.rotationSpeed;
            cube.rotation.z += controls.rotationSpeed;

            // bounce the sphere up and down
            step += controls.bouncingSpeed;
            sphere.position.x = 20 + ( 10 * (Math.cos(step)));
            sphere.position.y = 2 + ( 10 * Math.abs(Math.sin(step)));

            requestAnimationFrame(render);
            renderer.render(scene, camera);
        }

        function initStats() {

            var stats = new Stats();

            stats.setMode(0); // 0: fps, 1: ms

            // Align top-left
            stats.domElement.style.position = 'absolute';
            stats.domElement.style.left = '0px';
            stats.domElement.style.top = '0px';

            document.getElementById("Stats-output").appendChild(stats.domElement);

            return stats;
        }
    };

    window.onload = init;