The fovMapping controls which dimension of the applet corresponds to
the camera field of view. When you resize the browser, the field of view
in the fovMapping dimension will remain the same.
SHORTEST fovMapping - the shorter of vertical/horizontal will match the fov.
HORIZONTAL fovMapping - horizontal fov remains constant.
VERTICAL fovMapping - vertical fov remains constant.
DIAGONAL fovMapping - diagonal fov remains constant.