[ghaff]

I have no idea how that works with AR overlaying monitors on a physical worldview. So you're writing something overlaid on the view around the coffeeshop? The idea of AR is more to give a HUD that provides information about what you're looking at.

[psyc]

AR is commonly used to insert solid objects into the real world. See Pokemon Go and most HoloLens games. And the HoloLens app where a virtual dog lives in your house.

[bathtub365]

HoloLens is not able to render opaque objects. They always have some level of translucency, and the darker the colour of the object, the more translucent it is.