Get lightmapGI UV scale and offset for a mesh

[Noobot9k]

LightmapGI.light_data has a method called add_user that takes a "uv_scale" Rect2 parameter which represents scale and offset. I would like access to this data. Perhaps light_data should have a get_user_uv_scale method that takes a node as a parameter and returns a Rect2?

My use case is that I am creating a system that allows players to paint the entire 3D world. This means I need to have a megatexture that acts as a mask that stores what parts of the world have been painted. All 3D geometry needs to be represented on this texture with no overlaps and the system needs to be able to handle a mix of meshes that were exported from different Blender projects, downloaded from the internet, and primitive MeshInstance3Ds like boxes and spheres. Sounds like the perfect job for lightmap UVs!

The problem I'm facing is that the UV2s that I have access to are all overlapping. This is because I don't have access to the scale/offset that UV2 uses when applying the lightmap. The lightmap is all one giant texture and each mesh's UV2s are scaled/offset to ensure none of them overlap, as I understand it.

[Noobot9k]

looks like scene\3d\lightmap_gi.cpp in the engine source code has a method called LightmapGIData::get_user_lightmap_uv_scale that would do exactly what I want if exposed to GDScript.

[Noobot9k]

Looks like there's a hidden method called _get_user_data on LightmapGI.light_data that is exposed to gdscript but not shown in autocomplete/the docs that might do something like what I want.