Creating Holes in GeoMipTerrain?

Hey everybody! Long time reader, first time poster. I’ve been reading these boards for so long, I feel like I’ve known some of the regulars for years. :smiley: I’m starting to get my hands dirty with terrain generation using Panda3D. I do have a question, however, regarding GeoMipTerrain.

Say I want to build a structure that goes “underground”, beneath the terrain object. I need to be able to select certain triangles and “turn them off”, so to speak. i.e. Not render them, and allow a player to pass through without colliding.

Has anyone else tackled this problem, and can anyone give me some pointers on how to pursue this with a GeoMipTerrain object?

Thanks a bunch!

I use the AlphaTestAttrib for that sort of stuff:
panda3d.org/manual/index.php/Alpha_Testing
and have a texture where black means holes, and white means visible.

Yeah, that’s pretty much the approach I was looking at, too. What scale alpha map do you use? The same as your heightmap? Or higher?

Totally depends on how big your holes are and what shape exactly.
Usually, I don’t need that much detail, because I dont care if the hole isn’t exactly round - I make sure my ‘cave’ or so overlaps with part of the terrain.