How to get a UV point on a mesh from a 3D point?

Azedaxen

Is it possible to use a 3D point on a mesh to get the corresponding UV point?

Here's why I'm trying to do this, in case there's another approach that would work better:

I'm working on a game where surfaces can get marked as "contaminated", causing debuffs when the player is standing on them. The game keeps track of which parts of the level are contaminated using a 2D L8-format texture, black representing contaminated surfaces and white being uncontaminated.

The map so far is mostly flat, which allows the UV map to map to world coordinates along the XZ plane perfectly as long as all faces are visible from a top orthographic view. The problem with this approach is that it does not work with walls or room-over-room architecture. This would be easily solved if it were possible to get UV points from 3D space.

TwistedTwigleg

I have not poked around the code, but this Godot Texture Painter GitHub repository might be helpful, as it seems to, somehow, convert the mouse position to UV space.

Here's another repository that may be helpful. It's three years old, but the method may still be usable.