Nice job Baker.>So LordHavoc sort of bypassed everything and went straight to the end result. Am I right so far?
What happened so far, I think, is about this:
Urre used me and avirox to experiment using a rotate_* and a point entity (ie no oigin brushes, origin taken from a point entity) and demonstrated that it was already possible, we got stuff rotating this way in Darkplaces with collision. Dunno what QC avirox used. The important part is that the bmodel's name has to start with rotate_*.
Then what LH did was fixing a compiler bug (my testmaps were not working correctly although they compiled fine) to make this work more reliably. Apparently a similar bug exists in treeqbsp (AguirRe's and Tyrann's versions). I don't know which compiler introduced this bug, or if all of them have it. Then LH kept experimenting using a func_wall (ie no rotate_*) with avelocity set and origin set manually (no point entity, no origin brushes).
My point was that using either a point entity or origin brushes is more user friendly because origin brushes are basically how it's done everywhere else, to which Urre and Xavior agreed in principle.
Origin brushes indeed are only used to set the origin for the rotating bmodel and are stripped out (or simply not displayed) when no longer necessary (how you do that is up to you, I guess, from what I saw looking at a Q2 compiler, it did this via having a content type for origin-textured brushes (so they're just invisible and nonsolid in the game I guess). All that matters about origin brushes is that a mapper can use them in a map editor, how and when they're removed (map compiler, engine) is pretty irrelevant AFAIK.
that's my limited knowledge, IDK how LH does it atm in the engine.
Edit: In Half-Life, the rotating brush and the origin brush belong to the same model / entity. Unlike with Hipnotic rotating entities, no target/targetname setup is used. Like this:
http://halflife.qeradiant.com/halflife/bthl6.htm
An origin brush is simply defined as a brush textured on all sides with an origin texture. An origin texture is a texture whose name is "origin". Works like a sky brush.