blackhole('#blackhole'); function blackhole(element) { var h = $(element).height(), w = $(element).width(), cw = w, ch = h, maxorbit = 255, // distance from center centery = ch/2, centerx = cw/2; var startTime = new Date().getTime(); var currentTime = 0; var stars = [], collapse = false, // if hovered expanse = false; // if clicked var canvas = $('<canvas/>').attr({width: cw, height: ch}).appendTo(element), context = canvas.get(0).getContext("2d"); context.globalCompositeOperation = "multiply"; function setDPI(canvas, dpi) { // Set up CSS size if it's not set up already if (!canvas.get(0).style.width) canvas.get(0).style.width = canvas.get(0).width + 'px'; if (!canvas.get(0).style.height) canvas.get(0).style.height = canvas.get(0).height + 'px'; var scaleFactor = dpi / 96; canvas.get(0).width = Math.ceil(canvas.get(0).width * scaleFactor); canvas.get(0).height = Math.ceil(canvas.get(0).height * scaleFactor); var ctx = canvas.get(0).getContext('2d'); ctx.scale(scaleFactor, scaleFactor); } function rotate(cx, cy, x, y, angle) { var radians = angle, cos = Math.cos(radians), sin = Math.sin(radians), nx = (cos * (x - cx)) + (sin * (y - cy)) + cx, ny = (cos * (y - cy)) - (sin * (x - cx)) + cy; return [nx, ny]; } setDPI(canvas, 192); var star = function(){ // Get a weighted random number, so that the majority of stars will form in the center of the orbit var rands = []; rands.push(Math.random() * (maxorbit/2) + 1); rands.push(Math.random() * (maxorbit/2) + maxorbit); this.orbital = (rands.reduce(function(p, c) { return p + c; }, 0) / rands.length); // Done getting that random number, it's stored in this.orbital this.x = centerx; // All of these stars are at the center x position at all times this.y = centery + this.orbital; // Set Y position starting at the center y + the position in the orbit this.yOrigin = centery + this.orbital; // this is used to track the particles origin this.speed = (Math.floor(Math.random() * 2.5) + 1.5)*Math.PI/180; // The rate at which this star will orbit this.rotation = 0; // current Rotation this.startRotation = (Math.floor(Math.random() * 360) + 1)*Math.PI/180; // Starting rotation. If not random, all stars will be generated in a single line. this.id = stars.length; // This will be used when expansion takes place. this.collapseBonus = this.orbital - (maxorbit * 0.7); // This "bonus" is used to randomly place some stars outside of the blackhole on hover if(this.collapseBonus < 0){ // if the collapse "bonus" is negative this.collapseBonus = 0; // set it to 0, this way no stars will go inside the blackhole } stars.push(this); this.color = 'rgba(255,255,255,'+ (1 - ((this.orbital) / 255)) +')'; // Color the star white, but make it more transparent the further out it is generated this.hoverPos = centery + (maxorbit/2) + this.collapseBonus; // Where the star will go on hover of the blackhole this.expansePos = centery + (this.id%100)*-10 + (Math.floor(Math.random() * 20) + 1); // Where the star will go when expansion takes place this.prevR = this.startRotation; this.prevX = this.x; this.prevY = this.y; // The reason why I have yOrigin, hoverPos and expansePos is so that I don't have to do math on each animation frame. Trying to reduce lag. } star.prototype.draw = function(){ // the stars are not actually moving on the X axis in my code. I'm simply rotating the canvas context for each star individually so that they all get rotated with the use of less complex math in each frame. if(!expanse){ this.rotation = this.startRotation + (currentTime * this.speed); if(!collapse){ // not hovered if(this.y > this.yOrigin){ this.y-= 2.5; } if(this.y < this.yOrigin-4){ this.y+= (this.yOrigin - this.y) / 10; } } else { // on hover this.trail = 1; if(this.y > this.hoverPos){ this.y-= (this.hoverPos - this.y) / -5; } if(this.y < this.hoverPos-4){ this.y+= 2.5; } } } else { this.rotation = this.startRotation + (currentTime * (this.speed / 2)); if(this.y > this.expansePos){ this.y-= Math.floor(this.expansePos - this.y) / -140; } } context.save(); context.fillStyle = this.color; context.strokeStyle = this.color; context.beginPath(); var oldPos = rotate(centerx,centery,this.prevX,this.prevY,-this.prevR); context.moveTo(oldPos[0],oldPos[1]); context.translate(centerx, centery); context.rotate(this.rotation); context.translate(-centerx, -centery); context.lineTo(this.x,this.y); context.stroke(); context.restore(); this.prevR = this.rotation; this.prevX = this.x; this.prevY = this.y; } $('.centerHover').on('click',function(){ collapse = false; expanse = true; $(this).addClass('open'); $('.fullpage').addClass('open'); setTimeout(function(){ $('.header .welcome').removeClass('gone'); }, 500); }); $('.centerHover').on('mouseover',function(){ if(expanse == false){ collapse = true; } }); $('.centerHover').on('mouseout',function(){ if(expanse == false){ collapse = false; } }); window.requestFrame = (function(){ return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || function( callback ){ window.setTimeout(callback, 1000 / 60); }; })(); function loop(){ var now = new Date().getTime(); currentTime = (now - startTime) / 50; context.fillStyle = 'rgba(25,25,25,0.2)'; // somewhat clear the context, this way there will be trails behind the stars context.fillRect(0, 0, cw, ch); for(var i = 0; i < stars.length; i++){ // For each star if(stars[i] != stars){ stars[i].draw(); // Draw it } } requestFrame(loop); } function init(time){ context.fillStyle = 'rgba(25,25,25,1)'; // Initial clear of the canvas, to avoid an issue where it all gets too dark context.fillRect(0, 0, cw, ch); for(var i = 0; i < 2500; i++){ // create 2500 stars new star(); } loop(); } init(); }

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