Terrain hole mask (for caves, tunnels, basements)
Megan Starchild
Request: a per-cell hole mask on region terrain, applied to both rendering and collision.
- Region terrain gets a bitmask (e.g. one bit per 4m×4m cell) marking cells as "no ground."
- The viewer skips the triangles for masked cells.
- The physics heightfield leaves those cells out, and the sim's ground-penetration correction ignores them.
- Editing uses the same terraform permissions as painting.
This would allow real cave entrances, mine shafts, and sunken basements instead of faking them with mesh shells over raised terrain. Open questions for the Lab: what happens at region borders, and what to do with avatars or objects that fall through a hole with nothing built underneath (e.g. treat them like falling off the world edge, or keep a floor below the minimum terrain height).
WoW's ADT terrain uses this same approach: a hole bitmask per chunk that both the renderer and the collision code respect.
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AlettaMondragon Resident
Funny, I found this last night:
And I was thinking about the exact same things you have written here, Megan.
My doubt in this implementation is that it probably wouldn't be reliable, knowing terrain and physics in SL. So I was thinking, "if we have a hole in the terrain at point A and another at point B on two sides of a mountain, we can build a tunnel with objects". Alright, but then what would happen above the tunnel? Would the terrain position still be reliable there? What if there is a collision physics gap between the hole and the object, or if there is no object, would we be able to just fly around underground without limits? What should the depth limit be? How would we prevent people from being able to build hidden tunnels far underground through other people's lands? (Objects can already get lost and stuck at 0 altitude and it can get difficult to find the object if it's far underground.
So your idea is definitely better than the older one I linked, but I still have my doubts.
Aranui Littlebird
Good suggestion! This would allow more possibilities for developing subterranean builds, bunkers and tunnels. It would also be good for the gaming communities LL are trying to appeal to. The cave structure I created in a large sky dome would be impossible currently at ground level.