Kepler/engine/utils.js

var WebGLUtils = function() {

	/**
	 * Creates the HTLM for a failure message
	 * @param {string} canvasContainerId id of container of th
	 *        canvas.
	 * @return {string} The html.
	 */
	var makeFailHTML = function(msg) {
	  return '' +
		'<table style="background-color: #8CE; width: 100%; height: 100%;"><tr>' +
		'<td align="center">' +
		'<div style="display: table-cell; vertical-align: middle;">' +
		'<div style="">' + msg + '</div>' +
		'</div>' +
		'</td></tr></table>';
	};

	/**
	 * Mesasge for getting a webgl browser
	 * @type {string}
	 */
	var GET_A_WEBGL_BROWSER = '' +
	  'This page requires a browser that supports Webthis.gl.<br/>' +
	  '<a href="http://get.webthis.gl.org">Click here to upgrade your browser.</a>';

	/**
	 * Mesasge for need better hardware
	 * @type {string}
	 */
	var OTHER_PROBLEM = '' +
	  "It doesn't appear your computer can support Webthis.gl.<br/>" +
	  '<a href="http://get.webthis.gl.org/troubleshooting/">Click here for more information.</a>';

	/**
	 * Creates a webgl context. If creation fails it will
	 * change the contents of the container of the <canvas>
	 * tag to an error message with the correct links for Webthis.gl.
	 * @param {Element} canvas. The canvas element to create a
	 *     context from.
	 * @param {WebGLContextCreationAttirbutes} opt_attribs Any
	 *     creation attributes you want to pass in.
	 * @param {function:(msg)} opt_onError An function to call
	 *     if there is an error during creation.
	 * @return {WebGLRenderingContext} The created context.
	 */
	var setupWebGL = function(canvas, opt_attribs, opt_onError) {
	  function handleCreationError(msg) {
		var container = canvas.parentNode;
		if (container) {
		  var str = window.WebGLRenderingContext ?
			   OTHER_PROBLEM :
			   GET_A_WEBGL_BROWSER;
		  if (msg) {
			str += "<br/><br/>Status: " + msg;
		  }
		  container.innerHTML = makeFailHTML(str);
		}
	  };

	  opt_onError = opt_onError || handleCreationError;

	  if (canvas.addEventListener) {
		canvas.addEventListener("webglcontextcreationerror", function(event) {
			  opt_onError(event.statusMessage);
			}, false);
	  }
	  var context = create3DContext(canvas, opt_attribs);
	  if (!context) {
		if (!window.WebGLRenderingContext) {
		  opt_onError("");
		}
	  }
	  return context;
	};

	/**
	 * Creates a webgl context.
	 * @param {!Canvas} canvas The canvas tag to get context
	 *     from. If one is not passed in one will be created.
	 * @return {!WebGLContext} The created context.
	 */
	var create3DContext = function(canvas, opt_attribs) {
	  var names = ["webgl", "experimental-webgl", "webkit-3d", "moz-webgl"];
	  var context = null;
	  for (var ii = 0; ii < names.length; ++ii) {
		try {
		  context = canvas.getContext(names[ii], opt_attribs);
		} catch(e) {}
		if (context) {
		  break;
		}
	  }
	  return context;
	}

	return {
	  create3DContext: create3DContext,
	  setupWebGL: setupWebGL
	};
}();

/**
 * Provides requestAnimationFrame in a cross browser way.
 */
window.requestAnimFrame = (function() {
  return window.requestAnimationFrame ||
         window.webkitRequestAnimationFrame ||
         window.mozRequestAnimationFrame ||
         window.oRequestAnimationFrame ||
         window.msRequestAnimationFrame ||
         function(/* function FrameRequestCallback */ callback, /* DOMElement Element */ element) {
           window.setTimeout(callback, 1000/60);
         };
})();


export {WebGLUtils as default};