/*
           * AUTHOR: Iacopo Sassarini
           */

        if ( ! Detector.webgl ) Detector.addGetWebGLMessage();

        var VISUALS_VISIBLE = true;

        var SCALE_FACTOR = 1500;
        var CAMERA_BOUND = 200;

        var NUM_POINTS_SUBSET = 40000;
        var NUM_SUBSETS       = 7;
        var NUM_POINTS = NUM_POINTS_SUBSET * NUM_SUBSETS;

        var NUM_LEVELS = 5;
        var LEVEL_DEPTH = 400;

        var DEF_BRIGHTNESS = 1;
        var DEF_SATURATION = 0.8;

        var SPRITE_SIZE = Math.ceil(3 * window.innerWidth /1600);

        // Orbit parameters constraints
        var A_MIN = -30;
        var A_MAX = 30;
        var B_MIN = .2;
        var B_MAX = 1.8;
        var C_MIN = 5;
        var C_MAX = 17;
        var D_MIN = 0;
        var D_MAX = 10;
        var E_MIN = 0;
        var E_MAX = 12;

        // Orbit parameters
        var a, b, c, d, e;

        // Orbit data
        var orbit = {
            subsets: [],
            xMin: 0,
            xMax: 0,
            yMin: 0,
            yMax: 0,
            scaleX: 0,
            scaleY: 0
        }
        // Initialize data points
        for (var i = 0; i < NUM_SUBSETS; i++){
            var subsetPoints = [];
            for (var j = 0; j < NUM_POINTS_SUBSET; j++){
                subsetPoints[j] = {
                    x: 0,
                    y: 0,
                    vertex:  new THREE.Vertex(new THREE.Vector3(0,0,0))
                };
            }
            orbit.subsets.push(subsetPoints);
        }

        var container, stats;
        var camera, scene, renderer, composer, hueValues = [];

        var mouseX = 0, mouseY = 0;

        var windowHalfX = window.innerWidth / 2;
        var windowHalfY = window.innerHeight / 2;

        var speed = 6;
        var rotationSpeed = 0.005;

        init();
        animate();

        function init() {

            sprite1 = THREE.ImageUtils.loadTexture( "galaxy.png" );

            container = document.createElement( 'div' );
            document.body.appendChild( container );

            camera = new THREE.PerspectiveCamera(60, window.innerWidth / window.innerHeight, 1, 3 * SCALE_FACTOR );
            camera.position.z = SCALE_FACTOR/2;

            scene = new THREE.Scene();
            scene.fog = new THREE.FogExp2( 0x000000, 0.0012);

            generateOrbit();

            for (var s = 0; s < NUM_SUBSETS; s++){hueValues[s] = Math.random();}

            // Create particle systems
            for (var k = 0; k < NUM_LEVELS; k++){
                for (var s = 0; s < NUM_SUBSETS; s++){
                    var geometry = new THREE.Geometry();
                    for (var i = 0; i < NUM_POINTS_SUBSET; i++){geometry.vertices.push( orbit.subsets[s][i].vertex);}
                    var materials = new THREE.ParticleBasicMaterial( { size: (SPRITE_SIZE ), map: sprite1, blending: THREE.AdditiveBlending, depthTest: false, transparent : true } );
                    materials.color.setHSV(hueValues[s], DEF_SATURATION, DEF_BRIGHTNESS);
                    var particles = new THREE.ParticleSystem( geometry, materials );
                    particles.myMaterial = materials;
                    particles.myLevel = k;
                    particles.mySubset = s;
                    particles.position.x = 0;
                    particles.position.y = 0;
                    particles.position.z = - LEVEL_DEPTH * k - (s  * LEVEL_DEPTH / NUM_SUBSETS) + SCALE_FACTOR/2;
                    particles.needsUpdate = 0;
                    scene.add( particles );
                }
            }

            // Setup renderer and effects
            renderer = new THREE.WebGLRenderer( { clearColor: 0x000000, clearAlpha: 1, antialias: false } );
            renderer.setSize( window.innerWidth, window.innerHeight );

            container.appendChild( renderer.domElement );

            stats = new Stats();
            stats.domElement.style.position = 'absolute';
            stats.domElement.style.top = '5px';
            stats.domElement.style.right = '5px';
            container.appendChild( stats.domElement );

            // Setup listeners
            document.addEventListener( 'mousemove', onDocumentMouseMove, false );
            document.addEventListener( 'touchstart', onDocumentTouchStart, false );
            document.addEventListener( 'touchmove', onDocumentTouchMove, false );
            document.addEventListener( 'keydown', onKeyDown, false );
            window.addEventListener( 'resize', onWindowResize, false );

            // Schedule orbit regeneration
            setInterval(updateOrbit, 7000);
        }

        function animate() {
            requestAnimationFrame( animate );
            render();
            stats.update();
        }

        function render() {

            if (camera.position.x >= - CAMERA_BOUND && camera.position.x <= CAMERA_BOUND){
                camera.position.x += ( mouseX - camera.position.x ) * 0.05;
                if (camera.position.x < - CAMERA_BOUND) camera.position.x = -CAMERA_BOUND;
                if (camera.position.x >  CAMERA_BOUND) camera.position.x = CAMERA_BOUND;
            }
            if (camera.position.y >= - CAMERA_BOUND && camera.position.y <= CAMERA_BOUND){
                camera.position.y += ( - mouseY - camera.position.y ) * 0.05;
                if (camera.position.y < - CAMERA_BOUND) camera.position.y = -CAMERA_BOUND;
                if (camera.position.y >  CAMERA_BOUND) camera.position.y = CAMERA_BOUND;
            }

            camera.lookAt( scene.position );

            for( i = 0; i < scene.objects.length; i++ ) {
                scene.objects[i].position.z +=  speed;
                scene.objects[i].rotation.z += rotationSpeed;
                if (scene.objects[i].position.z > camera.position.z){
                    scene.objects[i].position.z = - (NUM_LEVELS -1) * LEVEL_DEPTH;
                    if (scene.objects[i].needsUpdate == 1){
                        scene.objects[i].geometry.__dirtyVertices = true;
                        scene.objects[i].myMaterial.color.setHSV( hueValues[scene.objects[i].mySubset], DEF_SATURATION, DEF_BRIGHTNESS);
                        scene.objects[i].needsUpdate = 0;
                    }
                }
            }

            renderer.render( scene, camera );
        }

        ///////////////////////////////////////////////
        // Hopalong Orbit Generator
        ///////////////////////////////////////////////
        function updateOrbit(){
            generateOrbit();
            for (var s = 0; s < NUM_SUBSETS; s++){
                hueValues[s] = Math.random();
            }
            for( i = 0; i < scene.objects.length; i++ ) {
                scene.objects[i].needsUpdate = 1;
            }

        }

        function generateOrbit(){
            var x, y, z, x1;
            var idx = 0;

            prepareOrbit();

            // Using local vars should be faster
            var al = a;
            var bl = b;
            var cl = c;
            var dl = d;
            var el = e;
            var subsets = orbit.subsets;
            var num_points_subset_l = NUM_POINTS_SUBSET;
            var num_points_l = NUM_POINTS;
            var scale_factor_l = SCALE_FACTOR;

            var xMin = 0, xMax = 0, yMin = 0, yMax = 0;

            for (var s = 0; s < NUM_SUBSETS; s++){

                // Use a different starting point for each orbit subset
                x = s * .005 * (0.5-Math.random());
                y = s * .005 * (0.5-Math.random());

                var curSubset = subsets[s];

                for (var i = 0; i < num_points_subset_l; i++){

                    // Iteration formula (generalization of the Barry Martin's original one)
                    z = (dl + Math.sqrt(Math.abs(bl * x - cl)));
                    if (x > 0) {x1 = y - z;}
                    else if (x == 0) {x1 = y;}
                    else {x1 = y + z;}
                    y = al - x;
                    x = x1 + el;

                    curSubset[i].x = x;
                    curSubset[i].y = y;

                    if (x < xMin) {xMin = x;}
                    else if (x > xMax) {xMax = x;}
                    if (y < yMin) {yMin = y;}
                    else if (y > yMax) {yMax = y;}

                    idx++;
                }
            }

            var scaleX = 2 * scale_factor_l / (xMax - xMin);
            var scaleY = 2 * scale_factor_l / (yMax - yMin);

            orbit.xMin = xMin;
            orbit.xMax = xMax;
            orbit.yMin = yMin;
            orbit.yMax = yMax;
            orbit.scaleX = scaleX;
            orbit.scaleY = scaleY;

            // Normalize and update vertex data
            for (var s = 0; s < NUM_SUBSETS; s++){
                var curSubset = subsets[s];
                for (var i = 0; i < num_points_subset_l; i++){
                    curSubset[i].vertex.position.x = scaleX * (curSubset[i].x - xMin) - scale_factor_l;
                    curSubset[i].vertex.position.y = scaleY * (curSubset[i].y - yMin) - scale_factor_l;
                }
            }
        }

        function prepareOrbit(){
            shuffleParams();
            orbit.xMin = 0;
            orbit.xMax = 0;
            orbit.yMin = 0;
            orbit.yMax = 0;
        }

        function shuffleParams() {
            a = A_MIN + Math.random() * (A_MAX - A_MIN);
            b = B_MIN + Math.random() * (B_MAX - B_MIN);
            c = C_MIN + Math.random() * (C_MAX - C_MIN);
            d = D_MIN + Math.random() * (D_MAX - D_MIN);
            e = E_MIN + Math.random() * (E_MAX - E_MIN);
        }

        ///////////////////////////////////////////////
        // Event listeners
        ///////////////////////////////////////////////
        function onDocumentMouseMove( event ) {
            mouseX = event.clientX - windowHalfX;
            mouseY = event.clientY - windowHalfY;
        }

        function onDocumentTouchStart( event ) {
            if ( event.touches.length == 1 ) {
                event.preventDefault();
                mouseX = event.touches[ 0 ].pageX - windowHalfX;
                mouseY = event.touches[ 0 ].pageY - windowHalfY;
            }
        }

        function onDocumentTouchMove( event ) {
            if ( event.touches.length == 1 ) {
                event.preventDefault();
                mouseX = event.touches[ 0 ].pageX - windowHalfX;
                mouseY = event.touches[ 0 ].pageY - windowHalfY;
            }
        }

        function onWindowResize( event ) {
            windowHalfX = window.innerWidth / 2;
            windowHalfY = window.innerHeight / 2;
            camera.aspect = window.innerWidth / window.innerHeight;
            camera.updateProjectionMatrix();
            renderer.setSize( window.innerWidth, window.innerHeight );
        }

        function onKeyDown(event){
            if(event.keyCode == 38 && speed < 20) speed += .5;
            else if(event.keyCode == 40 && speed > 0) speed -= .5;
            else if(event.keyCode == 37) rotationSpeed += .001;
            else if(event.keyCode == 39) rotationSpeed -= .001;
            else if(event.keyCode == 72 || event.keyCode == 104) toggleVisuals();
        }

        function showHideAbout() {
            if (document.getElementById('about').style.display == "block") {
                document.getElementById('about').style.display = "none";
            } else {
                document.getElementById('about').style.display = "block";
            }
        }

        function toggleVisuals(){
            if(VISUALS_VISIBLE){
                document.getElementById('plusone').style.display = 'none';
                document.getElementById('tweet').style.display = 'none';
                document.getElementById('fb').style.display = 'none';
                document.getElementById('aboutlink').style.display = 'none';
                document.getElementById('about').style.display = 'none';
                document.getElementById('info').style.display = 'none';
                document.getElementById('chaosnebula').style.display = 'none';
                stats.domElement.style.display = 'none';
                renderer.domElement.style.cursor = "none";
                VISUALS_VISIBLE = false;
            }
            else {
                document.getElementById('plusone').style.display = 'block';
                document.getElementById('tweet').style.display = 'block';
                document.getElementById('fb').style.display = 'block';
                document.getElementById('aboutlink').style.display = 'block';
                document.getElementById('info').style.display = 'block';
                document.getElementById('chaosnebula').style.display = 'block';
                stats.domElement.style.display = 'block';
                renderer.domElement.style.cursor = "";
                VISUALS_VISIBLE = true;
            }
        }