User interfaces

• If a floating menu, web browser, or other kind of virtual display appears, then it should be rendered at least two meters away from the user's viewpoint to minimize vergence-accommodation mismatch (Section 5.4).
• Such a virtual display should be centered and have a relatively narrow field of view, approximately one-third of the total viewing area, to minimize eye and head movement. (Section 5.3).
• Embedding menus, options, game status, and other information may be most comfortable if it appears to be written into the virtual world in ways that are familiar; this follows the universal simulation principle (Chapter 10).