by Spike » Sun Dec 08, 2013 10:48 am
it enables compiler warnings...
wait...
actually, it allows
a) killtarget to remove walls.
b) triggering to change animations.
c) selective spawning (via spawnflags) so you can remove them in deathmatch to open up your map.
it has also been used to
d) reduce world bsp complexity, improving vis times, acting as a poor-man's func_detail.
it is implemented by the gamecode, and is just a solid bsp object like any door or train or plat or whatever is. the engine and qbsp have no special awareness.
.