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rhill-voronoi-demo2.html
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rhill-voronoi-demo2.html
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<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title>Javascript implementation of Steven Fortune's algorithm to compute Voronoi diagrams: Demo 2</title>
<meta name="Keywords" lang="en" content="voronoi, fortune, javascript, raymond hill"/>
<!--[if lte IE 8]><script type="text/javascript" src="excanvas/excanvas.compiled.js"></script><![endif]-->
<script type="text/javascript" src="rhill-voronoi-core.min.js"></script>
<style type="text/css">
body {font-family:tahoma,verdana,arial;font-size:13px;margin:0;padding:0}
body > div {margin-left:4px;margin-right:4px;}
body > div > div {margin:0;border:1px solid #ccc;border-top:0;padding:4px;}
h1 {margin:0 0 0.5em 0;padding: 4px 5em 4px 4px;font:bold large sans-serif;background-color:#c9d7f1;}
h4 {font-size:14px;margin:0.5em 0 0 0;border:0;border-bottom:solid 1px #c9d7f1;padding:2px;background-color:#e5ecf9;}
h4 > span {cursor:pointer}
#canvasParent {margin-top:0;margin-bottom:1em;padding:0;border:0}
#voronoiCode {font:11px monospace;overflow:auto;color:#666;}
#voronoiCode span {color:green;font-weight:bold;}
</style>
<script id="script" type="text/javascript">
var VoronoiDemo = {
voronoi: new Voronoi(),
sites: [],
diagram: null,
margin: 100,
canvas: null,
bbox: {xl:0,xr:800,yt:0,yb:600},
normalizeEventCoords: function(target,e) {
// http://www.quirksmode.org/js/events_properties.html#position
// =====
if (!e) {e=self.event;}
var x = 0;
var y = 0;
if (e.pageX || e.pageY) {
x = e.pageX;
y = e.pageY;
}
else if (e.clientX || e.clientY) {
x = e.clientX+document.body.scrollLeft+document.documentElement.scrollLeft;
y = e.clientY+document.body.scrollTop+document.documentElement.scrollTop;
}
// =====
return {x:x-target.offsetLeft,y:y-target.offsetTop};
},
init: function() {
var me = this;
this.canvas = document.getElementById('voronoiCanvas');
this.canvas.onmousemove = function(e) {
if (!me.sites.length) {return;}
var site = me.sites[0];
var mouse = me.normalizeEventCoords(me.canvas,e);
site.x = mouse.x;
site.y = mouse.y;
me.diagram = me.voronoi.compute(me.sites,me.bbox);
me.render();
};
this.canvas.onclick = function(e) {
var mouse = me.normalizeEventCoords(me.canvas,e);
me.addSite(mouse.x,mouse.y);
me.render();
};
this.randomSites(10,true);
this.render();
},
clearSites: function() {
// we want at least one site, the one tracking the mouse
this.sites = [{x:0,y:0}];
this.diagram = this.voronoi.compute(this.sites, this.bbox);
},
randomSites: function(n,clear) {
if (clear) {this.sites = [];}
var xo = this.margin;
var dx = this.canvas.width-this.margin*2;
var yo = this.margin;
var dy = this.canvas.height-this.margin*2;
for (var i=0; i<n; i++) {
this.sites.push({x:self.Math.round(xo+self.Math.random()*dx),y:self.Math.round(yo+self.Math.random()*dy)});
}
this.diagram = this.voronoi.compute(this.sites, this.bbox);
},
addSite: function(x,y) {
this.sites.push({x:x,y:y});
this.diagram = this.voronoi.compute(this.sites, this.bbox);
},
render: function() {
var ctx = this.canvas.getContext('2d');
// background
ctx.globalAlpha = 1;
ctx.beginPath();
ctx.rect(0,0,this.canvas.width,this.canvas.height);
ctx.fillStyle = '#fff';
ctx.fill();
ctx.strokeStyle = '#888';
ctx.stroke();
// voronoi
if (!this.diagram) {return;}
ctx.strokeStyle='#000';
// edges
var edges = this.diagram.edges,
nEdges = edges.length,
v;
if (nEdges) {
var edge;
ctx.beginPath();
while (nEdges--) {
edge = edges[nEdges];
v = edge.va;
ctx.moveTo(v.x,v.y);
v = edge.vb;
ctx.lineTo(v.x,v.y);
}
ctx.stroke();
}
// how many sites do we have?
var sites = this.sites,
nSites = sites.length;
if (!nSites) {return;}
// highlight cell under mouse
var cell = this.diagram.cells[this.sites[0].voronoiId];
// there is no guarantee a Voronoi cell will exist for any
// particular site
if (cell) {
var halfedges = cell.halfedges,
nHalfedges = halfedges.length;
if (nHalfedges > 2) {
v = halfedges[0].getStartpoint();
ctx.beginPath();
ctx.moveTo(v.x,v.y);
for (var iHalfedge=0; iHalfedge<nHalfedges; iHalfedge++) {
v = halfedges[iHalfedge].getEndpoint();
ctx.lineTo(v.x,v.y);
}
ctx.fillStyle = '#faa';
ctx.fill();
}
}
// draw sites
var site;
ctx.beginPath();
ctx.fillStyle = '#44f';
while (nSites--) {
site = sites[nSites];
ctx.rect(site.x-2/3,site.y-2/3,2,2);
}
ctx.fill();
},
};
</script>
</head>
<body onload="VoronoiDemo.init();">
<a href="https://github.com/gorhill/Javascript-Voronoi"><img style="position: absolute; top: 0; right: 0; border: 0;" src="https://s3.amazonaws.com/github/ribbons/forkme_right_red_aa0000.png" alt="Fork me on GitHub"></a>
<h1>Javascript implementation of Steven Fortune's algorithm to compute Voronoi diagrams<br/>Demo 2: A bit of interactivity added</h1>
<div id="divroot" style="width:800px;">
<p style="margin-top:0;margin-bottom:0"><a href="/voronoi/rhill-voronoi.html">< Back to main page</a><ul style="margin-top:0">
<li><a href="rhill-voronoi-demo1.html">Demo 1: measuring peformance</a>
<li><b>Demo 2: a bit of interactivity</b>
<li><a href="rhill-voronoi-demo3.php">Demo 3: Fancy tiling</a>
<li><a href="rhill-voronoi-demo4.html">Demo 4: Looking up a Voronoi cell using a quadtree</a>
<li><a href="rhill-voronoi-demo5.html">Demo 5: Lloyd's relaxation</a>
<li><a href="http://www.raymondhill.net/blog/?p=458#comments">Comments</a>
</ul></p>
<h4 class="divhdr">Sites generator</h4>
<div class="divinfo" id="voronoiGenerator">
<input type="button" value="Generate" onclick="VoronoiDemo.randomSites(parseInt(document.getElementById('voronoiNumberSites').value,10),true);VoronoiDemo.render();"/> or <input type="button" value="Add" onclick="VoronoiDemo.randomSites(parseInt(document.getElementById('voronoiNumberSites').value,10),false);VoronoiDemo.render();"/><input id="voronoiNumberSites" type="text" value="10" size="5" maxlength="5"/> sites randomly (Warning: performance might suffer the more sites you add.)
<br/><input id="voronoiClearSites" type="button" value="Clear all sites" onclick="VoronoiDemo.clearSites();VoronoiDemo.render();"/>
</div>
<h4 class="divhdr">Canvas</h4>
<div id="canvasParent">
<noscript>You need to enable Javascript in your browser for this page to display properly.</noscript>
<canvas id="voronoiCanvas" style="cursor:crosshair" width="800" height="600"></canvas>
<div id="voronoiNoCanvasAlert" style="display:none;padding:1em;background-color:#fcc;color:black;">
<p>Your browser doesn't support the HTML5 <canvas> element technology.</p>
<p>See <a target="_blank" href="http://en.wikipedia.org/wiki/Canvas_(HTML_element)">Wikipedia</a> for information on which browsers support the <u>HTML5 <canvas></u> technology.</p>
</div>
</div>
<h4 class="divhdr">Javascript source code for this page</h4>
<div class="divinfo" id="voronoiCode">
<pre>
<span><script type="text/javascript" src="<a href="rhill-voronoi-core.js" target="_blank">rhill-voronoi-core.js</a>"></script></span>
...
<div id="scriptContainer"></div>
...
</pre>
</div>
</div>
<script>
(function(){
var srcElem = document.getElementById("script");
if (srcElem) {
var dstElem = document.getElementById("scriptContainer");
if (dstElem) {
dstElem.innerText = srcElem.innerHTML;
}
}
})();
</script>
</body>
</html>