LayoutTests/compositing/webgl/webgl-repaint.html - WebKit - Git at Google

 <!DOCTYPE html>
 <html>
 <head>
 <style type="text/css" media="screen">
 canvas {
     margin: 20px;
     width: 200px;
     height: 200px;
     padding: 0 0;
 }
 .border {
     border: 1px solid black;
 }
 </style>
 <script>
 function initWebGL()
 {
     var canvas = document.getElementById('canvas');
     var gl = canvas.getContext("experimental-webgl", {'antialias': false});
     if (!gl) {
         alert("No WebGL context found");
         return null;
     }

     return gl;
 }

 var gl = null;

 function init()
 {
   gl = initWebGL();
   gl.viewport(0, 0, 200, 200);
   gl.clearColor(1, 0, 0, 1); // red
   gl.clear(gl.COLOR_BUFFER_BIT);
   if (window.testRunner) {
       testRunner.displayAndTrackRepaints();
       testRunner.dumpAsText(true);
       drawGreen();
   } else
       window.setTimeout(drawGreen, 50);
 }

 function drawGreen()
 {
   gl.clearColor(0, 1, 0, 1); // green
   gl.clear(gl.COLOR_BUFFER_BIT);
   if (window.testRunner) {
       testRunner.displayAndTrackRepaints();
       testRunner.displayAndTrackRepaints();
   } else
       window.setInterval(function() {
         document.getElementById('canvas').classList.toggle('border');
       }, 50);
 }

 </script>
 </head>
 <body onload="init()">
 <canvas id="canvas" width="200" height="200"></canvas>
 </body>
 </html>
	<!DOCTYPE html>
	<html>
	<head>
	<style type="text/css" media="screen">
	canvas {
	margin: 20px;
	width: 200px;
	height: 200px;
	padding: 0 0;
	}
	.border {
	border: 1px solid black;
	}
	</style>
	<script>
	function initWebGL()
	{
	var canvas = document.getElementById('canvas');
	var gl = canvas.getContext("experimental-webgl", {'antialias': false});
	if (!gl) {
	alert("No WebGL context found");
	return null;
	}

	return gl;
	}

	var gl = null;

	function init()
	{
	gl = initWebGL();
	gl.viewport(0, 0, 200, 200);
	gl.clearColor(1, 0, 0, 1); // red
	gl.clear(gl.COLOR_BUFFER_BIT);
	if (window.testRunner) {
	testRunner.displayAndTrackRepaints();
	testRunner.dumpAsText(true);
	drawGreen();
	} else
	window.setTimeout(drawGreen, 50);
	}

	function drawGreen()
	{
	gl.clearColor(0, 1, 0, 1); // green
	gl.clear(gl.COLOR_BUFFER_BIT);
	if (window.testRunner) {
	testRunner.displayAndTrackRepaints();
	testRunner.displayAndTrackRepaints();
	} else
	window.setInterval(function() {
	document.getElementById('canvas').classList.toggle('border');
	}, 50);
	}

	</script>
	</head>
	<body onload="init()">
	<canvas id="canvas" width="200" height="200"></canvas>
	</body>
	</html>