initialize webgl object

webgl.js

function initWebGL(canvas) {
  var gl;
  
  try {
    gl = canvas.getContext("webgl") || canvas.getContext("experimental-webgl");
  }catch(e) {
  	return;
  }
  
  if (!gl) {
    alert("Unable to initialize WebGL. Your browser may not support it.");
    return;
  }

  return gl;
}