or.getDisplays and know which device we'll be
        // presenting with.
        var glAttribs = {
          alpha: false,
          antialias: false, //!VRSamplesUtil.isMobile(),
          preserveDrawingBuffer: false //preserveDrawingBuffer
        };
        gl = webglCanvas.getContext("webgl", glAttribs);
        if (!gl) {
          gl = webglCanvas.getContext("experimental-webgl", glAttribs);
          if (!gl) {
            VRSamplesUtil.addError("Your browser does not support WebGL.");
            