How to show invisible terrain in source engine?

I want to see all items that can impede or expedite movement on a map. Invisible walls, invisible pathways, is there any way to do this ingame, and not in hammer? I want to know this for Garry's Mod and Team Fortress 2.

Best Answer

One thing you can try (with sv_cheats on) is the console command r_drawclipbrushes 2. This should draw all clipping brushes as solid objects, letting you see most invisible walls/floors/ceilings/etc. Set it back to 0 to turn it off.