leaflet-webgl-heatmap
Version:
A Leaflet plugin for a popular WebGL Heatmap library.
95 lines (86 loc) • 4.04 kB
HTML
<html>
<head>
<!-- script src="https://www.khronos.org/registry/webgl/sdk/debug/webgl-debug.js"></script -->
<script src="webgl-heatmap.js"></script>
<script type="text/javascript">
window.onload = function(){
var canvas = document.getElementsByTagName('canvas')[0];
var heatmap = createWebGLHeatmap({canvas: canvas, intensityToAlpha:true});
//var heatmap = createWebGLHeatmap({canvas: canvas, intensityToAlpha:true, alphaRange: [1, 0]}); // inverse transparency
//var heatmap = createWebGLHeatmap({canvas: canvas, intensityToAlpha:true, alphaRange: [0, 0.05]}); // steep transparency
//var heatmap = createWebGLHeatmap({canvas: canvas, intensityToAlpha:true, gradientTexture:'deep-sea-gradient.png'});
//var heatmap = createWebGLHeatmap({canvas: canvas, intensityToAlpha:false, gradientTexture:'skyline-gradient.png'});
//var heatmap = createWebGLHeatmap({width: 500, height: 500}); // statically sized heatmap
document.body.appendChild(heatmap.canvas);
var paintAtCoord = function(x, y){
var count = 0;
while(count < 200){
var xoff = Math.random()*2-1;
var yoff = Math.random()*2-1;
var l = xoff*xoff + yoff*yoff;
if(l > 1){
continue;
}
var ls = Math.sqrt(l);
xoff/=ls; yoff/=ls;
xoff*=1-l; yoff*=1-l;
count += 1;
heatmap.addPoint(x+xoff*50, y+yoff*50, 30, 2/300);
}
}
// event handling
var onTouchMove = function(evt){
evt.preventDefault();
var touches = evt.changedTouches;
for(var i=0; i<touches.length; i++){
var touch = touches[i];
paintAtCoord(touch.pageX, touch.pageY);
}
};
canvas.addEventListener("touchmove", onTouchMove, false);
canvas.onmousemove = function(event){
var x = event.offsetX || event.clientX;
var y = event.offsetY || event.clientY;
paintAtCoord(x, y);
}
canvas.onclick = function(){
heatmap.clear();
}
var raf = window.requestAnimationFrame || window.mozRequestAnimationFrame ||
window.webkitRequestAnimationFrame || window.msRequestAnimationFrame;
var update = function(){
//heatmap.addPoint(100, 100, 100, 10/255);
heatmap.adjustSize(); // can be commented out for statically sized heatmaps, resize clears the map
heatmap.update(); // adds the buffered points
heatmap.display(); // adds the buffered points
//heatmap.multiply(0.9995);
//heatmap.blur();
//heatmap.clamp(0.0, 1.0); // depending on usecase you might want to clamp it
raf(update);
}
raf(update);
}
</script>
<style type="text/css">
body,html,canvas{
width: 100%;
height: 100%;
margin: 0;
padding: 0;
font-family: sans-serif;
color: black;
overflow: hidden;
}
div.controls{
font-weight: bold;
position: absolute;
top: 10px;
left: 10px;
}
</style>
</head>
<body>
<canvas></canvas>
</body>
</html>