Heist game vision clipping?

[Keslinger]

Hey, all.

This isn't about Babylon specifically, so perhaps it belongs in a different forum.  I am doing this with Babylon, so maybe it belongs here   Let me know and I'll move it.  Actually, if someone knows the correct term for this, it would make my Google search much easier. apparently "you know, that thing that heist games use where it clips the view of guards or cameras" isn't a valid search term.

I'm trying to create a 'vision arc'.  I've attached a doodle (top down) that shows what I'm talking about.  Our guard (blue dot) can't see past walls (black).  I'm trying to create a visual representation of his view area (green). I'm thinking about this a couple of different ways, but none of them are really making me happy.  How do I go about creating this? I know it's been done before on Heist games that show you where the guard/camera can see.

1)  A shader, much like a spotlight shader, but from the guard's PoV?

2)   DepthRenderer (from the guard's perspective) and pass that texture to a fragment shader that uses it to figure out what to discard?

3) A whole bunch of raycasts and generate a mesh from where they hit things (or ray length)?

Any help would be appreciated!

 

[JohnK]

I know nothing about this but IMHO it must be difficult otherwise someone would have done the code so that the light from a spotlight would be blocked by a mesh but as you can see it is not.

http://www.babylonjs-playground.com/#20OAV9#31