OK, a problem has surfaced with very large rotating structures.
I have a pretty big rotate_door, which is part of a moving / rotating bridge. Problem is, the thing starts to "flicker" in non-Darkplaces engines, ie from certain angles, the thing becomes invisible.
AFAIK this happens when the thing is in too many vis leafs? portals? It gets much, much worse in a fullvised map. Probably because there are more vis (leafs/portals/whatever).
However: It doesn't happen in Darkplaces
. Yay. So there is a way to fix it. (It also doesn't flicker in AguirRe's enhanced GLquake, but that might stem from the fact that BJPquake doesn't support rotating bmodels. The flickering is in my modified Quakespasm - ie a Fitzquake-derived engine). Couldn't test with newest Proquake, which has rotation support, since it can't load the map.
I've also tried turning the rotate_door into a func_wall to see if it still flickers. Nope - the func_wall version does NOT flicker, but of course it also doesn't rotate and hence it can probably not be compared directly.
I'm asking someone like mh, LordHavoc, Baker or other engine capable person to give me a hand here. What does darkplaces do differently when it comes to vis culling? And once we find out, can that fix (I suppose it is a sort of fix) be applied to other engines?
I could probably also chop the thing up into a load of smaller rotate_doors, but I'm afraid this will mess up texturing and/or lighting - I'm glad the thing is textured somewhat correctly.
Why does it work in DP with no flickering, even when fullvised?
What to do?