So I’ve been experimenting with using decals to project props like letters for the players to see and use. It seems useful as it’s so easy to change the content and I can blend mats. But it’s URP so there’s no way of (afaik) using layers so the projection reange can’t be easily managed.
Most games I’ve seen use physical objects for props. Meaning a document on a table will be a flat plane with a texture.
I’m not sure why would you use projectors for props, as this is not what they’re for.
In scenario where you’d need a somewhat dynamic content (meaning a book where you can flip pages, but the text is from a file), the usual idea would be to use render to texture. And using RenderTextures allows you to blend things however you want.
If you don’t need it dynamically like that asset probably provides, just pre-render all clues at game startup onto render textures and use those with classic decal projection like there are tutorials out there for.