%header
  .container
    %h1 Direction-aware hover effect
    %p CSS & bits of JS
.container
  %ul
    - 12.times do
      %li
        %a{:href => "#", :class => "normal"}
          %svg{:viewBox => "0 0 80 76", :x => "0px", :y => "0px"}
            %g
              %path{:d => "M 68.9708 24.8623 L 60.4554 2.3018 C 59.9641 0.7017 58.1628 -0.2583 56.5252 0.3817 L 1.9822 20.2222 C 0.3822 20.7022 -0.4179 22.6222 0.2222 24.2223 L 8.8624 47.7797 L 8.8624 35.1484 C 8.8624 29.5024 13.3425 24.8623 18.8857 24.8623 L 32.9442 24.8623 L 50.63 12.862 L 60.7829 24.8623 L 68.9708 24.8623 L 68.9708 24.8623 ZM 77.098 32.0625 L 18.8857 32.0625 C 17.2512 32.0625 16.0625 33.4511 16.0625 35.1484 L 16.0625 72.8491 C 16.0625 74.5477 17.2512 75.9375 18.8857 75.9375 L 77.098 75.9375 C 78.742 75.9375 79.9376 74.5477 79.9376 72.8491 L 79.9376 35.1484 C 79.9376 33.4511 78.742 32.0625 77.098 32.0625 L 77.098 32.0625 ZM 73.0626 68.0625 L 23.9375 68.0625 L 23.9375 61.0852 L 31.4704 43.7232 L 42.7696 57.6777 L 53.4138 46.8062 L 67.1695 41.9375 L 73.0626 55.0815 L 73.0626 68.0625 L 73.0626 68.0625 Z"}
        .info
          %h3 Single-origin coffee whatever
          %p Williamsburg tofu polaroid, 90's Bushwick irony locavore ethnic meh messenger bag Truffaut jean shorts.

@import url(https://fonts.googleapis.com/css?family=Bree+Serif);

$duration: 300ms;
$timing-fn: ease;
$turquoise: #1ABC9C;
$wet-asphalt: #34495E;
$midnight-blue: #2C3E50;
$clouds: #ECF0F1;

/* the important bits */
li {
  perspective: 400px;
}

.info {
  // hide-initial-state
  transform: rotate3d(1,0,0, 90deg);
  
  width: 100%;
  height: 100%;
  padding: 20px;
  position: absolute;
  top: 0;
  left: 0;
  border-radius: 4px;
  pointer-events: none;
  background-color: transparentize($turquoise, .1);
}

.in-top .info {
   transform-origin: 50% 0%;
   animation: in-top $duration $timing-fn 0ms 1 forwards;
}
.in-right .info {
  transform-origin: 100% 0%;
  animation: in-right $duration $timing-fn 0ms 1 forwards;
}
.in-bottom .info {
  transform-origin: 50% 100%;
  animation: in-bottom $duration $timing-fn 0ms 1 forwards;
}
.in-left .info {
  transform-origin: 0% 0%;
  animation: in-left $duration $timing-fn 0ms 1 forwards;
}

.out-top .info {
  transform-origin: 50% 0%;
  animation: out-top $duration $timing-fn 0ms 1 forwards;
}
.out-right .info {
  transform-origin: 100% 50%;
  animation: out-right $duration $timing-fn 0ms 1 forwards;
}
.out-bottom .info {
  transform-origin: 50% 100%;
  animation: out-bottom $duration $timing-fn 0ms 1 forwards;
}
.out-left .info {
  transform-origin: 0% 0%;
  animation: out-left $duration $timing-fn 0ms 1 forwards;
}

@keyframes in-top {
  from {transform: rotate3d(-1,0,0, 90deg)}
  to   {transform: rotate3d(0,0,0, 0deg)}}
@keyframes in-right {
  from {transform: rotate3d(0,-1,0, 90deg)}
  to   {transform: rotate3d(0,0,0, 0deg)}}
@keyframes in-bottom {
  from {transform: rotate3d(1,0,0, 90deg)}
  to   {transform: rotate3d(0,0,0, 0deg)}}
@keyframes in-left {
  from {transform: rotate3d(0,1,0, 90deg)}
  to   {transform: rotate3d(0,0,0, 0deg)}}

@keyframes out-top {
  from {transform: rotate3d(0,0,0, 0deg)}
  to   {transform: rotate3d(-1,0,0, 104deg)}}
@keyframes out-right {
  from {transform: rotate3d(0,0,0, 0deg)}
  to   {transform: rotate3d(0,-1,0, 104deg)}}
@keyframes out-bottom {
  from {transform: rotate3d(0,0,0, 0deg)}
  to   {transform: rotate3d(1,0,0, 104deg)}}
@keyframes out-left {
  from {transform: rotate3d(0,0,0, 0deg)}
  to   {transform: rotate3d(0,1,0, 104deg)}}


/* you can ignore this ones */
ul {
  padding: 0;
  margin: 0 0 50px;

  &:after {
    content: "";
    display: table;
    clear: both;
  }
}

li {
  position: relative;
  float: left;
  width: 200px;
  height: 200px;
  margin: 5px;
  padding: 0;
  list-style: none;
  
  a  {
    display: inline-block;
    vertical-align: top;
    text-decoration: none;
    border-radius: 4px;
  }
  
  h3 {
    margin: 0;
    font-size: 16px;
    color: transparentize(#fff, .1);
  }
  
  p  {
    font-size: 12px;
    line-height: 1.5;
    color: transparentize(#fff, .2);
  }
  
  .normal {
    width: 100%;
    height: 100%;
    background-color: $clouds;
    color: transparentize($wet-asphalt, .4);
    box-shadow: inset 0 2px 20px darken($clouds, 2);
    text-align: center;
    font-size: 50px;
    line-height: 200px;
    
    svg {
      pointer-events: none;
      width: 50px;
      path {
        fill: transparentize($wet-asphalt, .8);
      }
    }
  }
}

* {
  box-sizing: border-box;
}

body {
  background-color: #fff;
}

h1 {
  margin: 0 auto 5px;
  text-align: center;
}

h3 {
  font-family: 'Bree Serif', serif;
}

.container {
  width: 840px;
  margin: 0 auto;
}

header {
  font-family: 'Bree Serif', serif;
  text-align: center;
  margin: 50px 0 25px;
  color: $wet-asphalt;
  
  p {
    margin: 0;
    color: transparentize($wet-asphalt, .6);
  }
}

// - Noel Delgado | @pixelia_me

const nodes = [].slice.call(document.querySelectorAll('li'), 0);
const directions  = { 0: 'top', 1: 'right', 2: 'bottom', 3: 'left' };
const classNames = ['in', 'out'].map((p) => Object.values(directions).map((d) => `${p}-${d}`)).reduce((a, b) => a.concat(b));

const getDirectionKey = (ev, node) => {
  const { width, height, top, left } = node.getBoundingClientRect();
  const l = ev.pageX - (left + window.pageXOffset);
  const t = ev.pageY - (top + window.pageYOffset);
  const x = (l - (width/2) * (width > height ? (height/width) : 1));
  const y = (t - (height/2) * (height > width ? (width/height) : 1));
  return Math.round(Math.atan2(y, x) / 1.57079633 + 5) % 4;
}

class Item {
  constructor(element) {
    this.element = element;    
    this.element.addEventListener('mouseover', (ev) => this.update(ev, 'in'));
    this.element.addEventListener('mouseout', (ev) => this.update(ev, 'out'));
  }
  
  update(ev, prefix) {
    this.element.classList.remove(...classNames);
    this.element.classList.add(`${prefix}-${directions[getDirectionKey(ev, this.element)]}`);
  }
}

nodes.forEach(node => new Item(node));