Fancy Image Slideshow with Delaunay Triangulation Transition Effects

Category: Javascript , Recommended , Slideshow | October 28, 2014
Author: Zeaklous
Views Total: 1,613 views
Official Page: Go to website
Last Update: October 28, 2014
License: MIT

Preview:

Fancy Image Slideshow with Delaunay Triangulation Transition Effects

Description:

An Html5 canvas based fancy image slideshow which automatically switches between images with cool delaunay triangulation transition effects. Built with delaunay.js and TweenMax.

How to use it:

Create an empty DIV element that will be served as a slideshow container.

<div id="container"></div>

Load the  delaunay.js and the TweenMax JS library at the bottom of the web page.

<script src="delaunay.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/gsap/1.14.1/TweenMax.min.js"></script>

Add the required CSS styles into your document.

canvas {
  position: absolute;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  -moz-backface-visibility: hidden;
  -ms-backface-visibility: hidden;
}

img {
  position: absolute;
  -webkit-transition: opacity .3s;
  transition: opacity .3s;
}

The JavaScript to add your images into the slideshow and to active the Delaunay Triangulation transition effects.

const TWO_PI = Math.PI * 2;

var images = [], 
  imageIndex = 0;

var image,
  imageWidth = 768,
  imageHeight = 485;
 
var vertices = [],
  indices = [],
  prevfrag = [],
  fragments = [];

var margin = 50;

var container = document.getElementById('container');

var clickPosition = [imageWidth * 0.5, imageHeight * 0.5];

window.onload = function() {
  TweenMax.set(container, {perspective:500});

  // images from http://www.hdwallpapers.in
  var urls = [
      '1.jpg',
      '2.jpg',
      '3.jpg',
      '4.jpg'
    ],
    image,
    loaded = 0;
  // very quick and dirty hack to load and display the first image asap
  images[0] = image = new Image();
    image.onload = function() {
      if (++loaded === 1) {
        
        for (var i = 1; i < 4; i++) {
          images[i] = image = new Image();

          image.src = urls[i];
        } 
        placeImage();
      }
    };
    image.src = urls[0]; 
};

function placeImage(transitionIn) {
  image = images[imageIndex];

  if (++imageIndex === images.length) imageIndex = 0;
  
  var num = Math.random();
  if(num < .25) {
    image.direction = "left";
  } else if(num < .5) {
    image.direction = "top";
  } else if(num < .75) {
    image.direction = "bottom";
  } else {
    image.direction = "right";
  }

  container.appendChild(image);
  image.style.opacity = 0;
  
  if (transitionIn !== false) {
    triangulateIn();
  }
}

function triangulateIn(event) {
  var box = image.getBoundingClientRect(),
    top = box.top,
    left = box.left;
  
  if(image.direction == "left") {
    clickPosition[0] = 0; 
    clickPosition[1] = imageHeight / 2;
  } else if(image.direction == "top") {
    clickPosition[0] = imageWidth / 2;
    clickPosition[1] = 0;
  } else if(image.direction == "bottom") {
    clickPosition[0] = imageWidth / 2;
    clickPosition[1] = imageHeight;
  } else if(image.direction == "right") {
    clickPosition[0] = imageWidth;
    clickPosition[1] = imageHeight / 2;
  } 
  

  triangulate();
  build();
}

function triangulate() {
  for(var i = 0; i < 40; i++) {    
    x = -margin + Math.random() * (imageWidth + margin * 2);
    y = -margin + Math.random() * (imageHeight + margin * 2);
    vertices.push([x, y]);
  }
  vertices.push([0,0]);
  vertices.push([imageWidth,0]);
  vertices.push([imageWidth, imageHeight]);
  vertices.push([0, imageHeight]);
  
  vertices.forEach(function(v) {
    v[0] = clamp(v[0], 0, imageWidth);
    v[1] = clamp(v[1], 0, imageHeight);
  });
  
  indices = Delaunay.triangulate(vertices);
}

function build() {
  var p0, p1, p2,
    fragment;

  var tl0 = new TimelineMax({onComplete:buildCompleteHandler});

  for (var i = 0; i < indices.length; i += 3) {
    p0 = vertices[indices[i + 0]];
    p1 = vertices[indices[i + 1]];
    p2 = vertices[indices[i + 2]];

    fragment = new Fragment(p0, p1, p2);

    var dx = fragment.centroid[0] - clickPosition[0],
      dy = fragment.centroid[1] - clickPosition[1],
      d = Math.sqrt(dx * dx + dy * dy),
      rx = 30 * sign(dy),
      ry = 90 * -sign(dx),
      delay = d * 0.003 * randomRange(0.9, 1.1);
    fragment.canvas.style.zIndex = Math.floor(d).toString();

    var tl1 = new TimelineMax(); 

    if(image.direction == "left") {
      rx = Math.abs(rx); 
      ry = 0;      
    } else if(image.direction == "top") {
      rx = 0;
      ry = Math.abs(ry);
    } else if(image.direction == "bottom") {
      rx = 0;
      ry = - Math.abs(ry);
    } else if(image.direction == "right") {
      rx = - Math.abs(rx);
      ry = 0;
    } 
    
    tl1.from(fragment.canvas, 1, {
        z:-50,
        rotationX:rx,
        rotationY:ry,
        scaleX:0,
        scaleY:0,
        ease:Cubic.easeIn
     });
    tl1.from(fragment.canvas, 0.4,{alpha:0}, 0.6);
    
    tl0.insert(tl1, delay);

    fragments.push(fragment);
    container.appendChild(fragment.canvas);
  }
}

function buildCompleteHandler() {
  // add pooling?
  image.style.opacity = 1;
  image.addEventListener('transitionend', function catchTrans() {
    fragments.forEach(function(f) {
      container.removeChild(f.canvas);
    });

    fragments.length = 0;
    vertices.length = 0;
    indices.length = 0;

    placeImage();
    this.removeEventListener('transitionend',catchTrans,false);
  }, false);
  
}

//////////////
// MATH UTILS
//////////////

function randomRange(min, max) {
  return min + (max - min) * Math.random();
}

function clamp(x, min, max) {
  return x < min ? min : (x > max ? max : x);
}

function sign(x) {
  return x < 0 ? -1 : 1;
}

//////////////
// FRAGMENT
//////////////

Fragment = function(v0, v1, v2) {
  this.v0 = v0;
  this.v1 = v1;
  this.v2 = v2;

  this.computeBoundingBox();
  this.computeCentroid();
  this.createCanvas();
  this.clip();
};
Fragment.prototype = {
  computeBoundingBox:function() {
    var xMin = Math.min(this.v0[0], this.v1[0], this.v2[0]),
      xMax = Math.max(this.v0[0], this.v1[0], this.v2[0]),
      yMin = Math.min(this.v0[1], this.v1[1], this.v2[1]),
      yMax = Math.max(this.v0[1], this.v1[1], this.v2[1]);

     this.box = {
      x:Math.round(xMin),
      y:Math.round(yMin),
      w:Math.round(xMax - xMin),
      h:Math.round(yMax - yMin)
    };

  },
  computeCentroid:function() {
    var x = (this.v0[0] + this.v1[0] + this.v2[0]) / 3,
      y = (this.v0[1] + this.v1[1] + this.v2[1]) / 3;

    this.centroid = [x, y];
  },
  createCanvas:function() {
    this.canvas = document.createElement('canvas');
    this.canvas.width = this.box.w;
    this.canvas.height = this.box.h;
    this.canvas.style.width = this.box.w + 'px';
    this.canvas.style.height = this.box.h + 'px';
    this.canvas.style.left = this.box.x + 'px';
    this.canvas.style.top = this.box.y + 'px';
    this.ctx = this.canvas.getContext('2d');
  },
  clip:function() {
    this.ctx.save();
    this.ctx.translate(-this.box.x, -this.box.y);
    this.ctx.beginPath();
    this.ctx.moveTo(this.v0[0], this.v0[1]);
    this.ctx.lineTo(this.v1[0], this.v1[1]);
    this.ctx.lineTo(this.v2[0], this.v2[1]);
    this.ctx.closePath();
    this.ctx.clip();
    this.ctx.drawImage(image, 0, 0);
    this.ctx.restore();
  }
};

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