In short: It's a magical placeholder that makes it so you don't have to type as much.
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It's a "windows thing", more than a "hammer thing". Windows has "environment variables". For example, the variable named "appdata" can be referenced in a command-line program, and windows will automatically stick in the value there.
For example, %appdata% translates to:
Code:
C:\Documents and Settings\your.username\Application Data\
%VProject% is set by the Source SDK launcher and by teh Vconfig.exe program (in the sdk) and identifies your "current game" to the SDK tools. For example, it might be:
Code:
c:\program files\valve\steam\steamapps\your_username\team fortress 2\tf\
Try going to Start->Run and typing in %vproject% and hit enter. It ought to open up your "current game".
Anything I -really- need to do besides zipping custom textures? Thanks guys..
If you've already done a "nice" compile (there are options that take longer and make the map bigger but with nicer lighting) then... pack your custom content, and finally
build cubemaps for the shiny surfaces.