Background map?

Is there a way for me to get Garry’s Mod to load up a 3D background map, like in Half-Life 2, instead of a picture? I know it would take longer to load if I did, but I don’t particularly care.

Go into Steam/steamapps/username/garrysmod/garrysmod/cfg and find a file called autoexec.cfg (if there isn’t one, just make one in Notepad).

Chances are this file will be blank, so just write in it:

map_background [mapname]

Replace [mapname] with whatever map you want. What this will do, however, is load Gmod like normal first, THEN load the map. It takes twice as long as normal loading and isn’t really worth it, but if you’re okay with the loading time then whatever.