I've been doing some mapping in Source and got a bit confused concerning the use of detail brushes.

According to all the tutorials on the web, the advantages of detail brushes are that they they don't split up the visleafs and brush faces.

When I use them in a map, though, they do tend to split brush faces. I've attached a pic of this. I made a block with two func_details and two func_brushes attached to them.

The func_brushes work fine, but the detail brushes seem to split the face they're attached to at some but not all vertices.

Does anyone know why this is? Or did I do something wrong which I can't seem to figure out?
Thanks!

No they arent, its very strange what you have there and ive never had it,

gonna sound silly but have you tried deleting them and making them again? do they overlap into the brush that they are splitting?

im gonna try and recreate this tonight but let me know if you get it sorted

Nope. the func_details are flush with the big block. I noticed this because there were several places on the map where this happens.

I just searched around the VERC forums and saw a few other threads about this, so it isn't just me apparently. No solutions were offered though, only a statement by Valve's Jeff Lane along the lines of "This should not be happening"...

Those post were from December or so, so I'm a bit irritated that it hasn't been fixed already.

I'm gonna check out some HL2 and CSS maps to see if this also occurs there... Maybe Valve uses a different version of the compile tools...

Edit: Just checked de_cbble. Same thing happens there. So obviously it's normal, but not intended. The splitting only happens though, if a detail brush vertex touches a world brush edge.

Interesting thought: Valve could probably squeeze a few more fps out of their maps if they recompiled them "correctly", without this bug...

hmm that issue is very weird, eitherway if you cant find an answer email valve and ask them about it - might be a bug. Dystopia found several and we were infact responsable for a lot of the SDK updates :P

Pretty sure this has happened for everyone, I remember a few others wondering about this months ago.