michael@0: "use strict";
michael@0: 
michael@0: function parseArgs() {
michael@0:   var query = window.location.search.substring(1);
michael@0: 
michael@0:   var split = query.split("&");
michael@0: 
michael@0:   var args = {}
michael@0:   for (var i = 0; i < split.length; i++) {
michael@0:     var pair = split[i].split("=");
michael@0: 
michael@0:     var key = pair[0];
michael@0:     var value = true;
michael@0:     if (pair.length >= 2) {
michael@0:       eval("value = " + decodeURIComponent(pair[1]) + ";");
michael@0:     }
michael@0: 
michael@0:     args[key] = value;
michael@0:   }
michael@0: 
michael@0:   return args;
michael@0: }
michael@0: 
michael@0: var gArgs = null;
michael@0: function arg(key) {
michael@0:   if (gArgs === null) {
michael@0:     gArgs = parseArgs();
michael@0:   }
michael@0: 
michael@0:   var ret = gArgs[key];
michael@0:   if (ret === undefined)
michael@0:     ret = false;
michael@0: 
michael@0:   return ret;
michael@0: }
michael@0: 
michael@0: function initGL(canvas) {
michael@0:   if (arg("nogl"))
michael@0:     return null;
michael@0: 
michael@0:   var gl = null;
michael@0: 
michael@0:   var withAA = arg("aa");
michael@0:   var withAlpha = arg("alpha");
michael@0:   var withDepth = arg("depth");
michael@0:   var withPremult = arg("premult");
michael@0:   var withPreserve = arg("preserve");
michael@0:   var withStencil = arg("stencil");
michael@0: 
michael@0:   try {
michael@0:     var argDict = {
michael@0:       alpha: withAlpha,
michael@0:       depth: withDepth,
michael@0:       stencil: withStencil,
michael@0:       antialias: withAA,
michael@0:       premultipliedAlpha: withPremult,
michael@0:       preserveDrawingBuffer: withPreserve,
michael@0:     };
michael@0:     gl = canvas.getContext("experimental-webgl", argDict);
michael@0:   } catch(e) {}
michael@0: 
michael@0:   return gl;
michael@0: }
michael@0: 
michael@0: function rAF(func) {
michael@0:   var raf = window.requestAnimationFrame || window.mozRequestAnimationFrame;
michael@0:   raf(func);
michael@0: }
michael@0: 
michael@0: var MAX_WAIT_FOR_COMPOSITE_DELAY_MS = 500;
michael@0: 
michael@0: function waitForComposite(func) {
michael@0:   var isDone = false;
michael@0:   var doneFunc = function () {
michael@0:     if (isDone)
michael@0:       return;
michael@0:     isDone = true;
michael@0:     func();
michael@0:   };
michael@0: 
michael@0:   rAF(doneFunc);
michael@0:   setTimeout(doneFunc, MAX_WAIT_FOR_COMPOSITE_DELAY_MS);
michael@0: }