Questions regarding detail.vbsp, lights.rad and GameData inside gameinfo.txt

I am having a few minor issues inside Source SDK’s Hammer. I am not sure whether these are because something is not configured properly by me, or because Garry’s Mod generally lacks these. Hopefully an individual will be able to clarify in this thread.

1. detail.vbsp

When Source SDK is configured towards Garry’s Mod, materials will be available that contain detail prop information. However, Garry’s Mod does not seem to provide a detail.vbsp file at all like other Source games do.

2. lights.rad

Inside “garrysmod content.gcf”, lights.rad can be found at the appropriate location, however the file is not copied locally. Is this why Hammer is unable to pick it up? Is Facepunch Studios supposed to mark this file to be copied over locally?

3. GameData inside gameinfo.txt

According to the official documentation on this, this is a property used to guide compilers. Portal 2 for example has this configured to “portal2.fgd”. Garry’s Mod does not have this configured, with the eventual mentioning in each compile log that this could not be located. The .fgd file has to be located in Hammer’s directory, which is pretty much the case for all official Valve Source games.

I have no idea what the effect is of having this excluded or included. But I would like to know.


  1. Garry’s Mod is supposed to grab the the detail.vbsp file provided by the game it is based on, or remove the detail prop information from the specific material files.
  2. lights.rad inside “garrysmod content.gcf” should be marked to copy over locally so that development tools can pick this up.
  3. I do not know what the benefit is of informing compiler tools of a .fgd file, so I am clueless about this one.

FGD files are used to load entities that are used in the game it represents. For example, some Garry’s Mod gamemodes include custom entities used in mapmaking, such as triggers that do a certain task that is unique to only that gamemode therefore the will sometimes have their own FGDs. Portal2.fgd will include the entities used in portal 2, but it will most likely not work in gmod due to them having different engine versions. As for lights.rad, it looks like it’s the same file used by the Half-Life 2, Episode 1 and 2 configs.

As far as I know, you can just extract and edit the lights.rad file from sourcesdk.gcf and use that as there doesn’t seem to be any changes between that and the one Garry’s Mod uses. For the gmod FGD, I’m sure you can just extract it from the gmod GCF file to somewhere and mount it using the GameData files settings in tools -> options.

Thank you for the response.

I am aware of that. The Valve wiki states the following about defining the Forge Game Data file inside gameinfo.txt:

It made me wonder, how important is the message in the compile output about the missing GameData key and value when it comes down to Garry’s Mod?

The outputted map seems to be indifferent regardless of whether I manually specify this, or leave it out of the gameinfo.txt file.