Mounting multiple games

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This code extends the Orange Box's AdditionalContentId system to support mounting of multiple Game Cache Files via the gameinfo.txt. It can be used with the Ep1 codebase too.

Warning: Your mod will run regardless of whether or not the user owns the game that you mount content for. If the game isn't owned the content will not be mounted, and error signs will appear everywhere instead!

If the content you want to mount is required in order to play your mod properly, you may want to hard-code the ID instead of relying it to be in the gameinfo.txt. Remember when doing this that the int you pass to filesystem->MountSteamContent() must be negative!

Note:The code below is version 2, and has ditched the previous subkey approach. It is not compatible with the AdditionalContentId { 220,380 } gameinfo.txt scheme.

The code

This code needs to be added to both the client and the server.

Client
Search cdll_client_init.cpp for MountAdditionalContent() and replace it. If it didn't already exist, add the code above CHLClient::Init, then call it from that function right before if ( CommandLine()->FindParm( "-textmode" ) ).
Server
Search gameinterface.cpp for MountAdditionalContent() and replace it. If it didn't already exist, add the code above CServerGameDLL::DLLInit and call before the gpGlobals = pGlobals; line in that func.
static void MountAdditionalContent()
{
	KeyValues *pMainFile = new KeyValues( "gameinfo.txt" );
#ifndef _WINDOWS
	// case sensitivity
	pMainFile->LoadFromFile( filesystem, "GameInfo.txt", "MOD" );
	if (!pMainFile)
#endif
	pMainFile->LoadFromFile( filesystem, "gameinfo.txt", "MOD" );
	
	if (pMainFile)
	{
		KeyValues* pFileSystemInfo = pMainFile->FindKey( "FileSystem" );
		if (pFileSystemInfo)
			for ( KeyValues *pKey = pFileSystemInfo->GetFirstSubKey(); pKey; pKey = pKey->GetNextKey() )
			{
				if ( strcmp(pKey->GetName(),"AdditionalContentId") == 0 )
				{
					int appid = abs(pKey->GetInt());
					if (appid)
						if( filesystem->MountSteamContent(-appid) != FILESYSTEM_MOUNT_OK )
							Warning("Unable to mount extra content with appId: %i\n", appid);
				}
			}
	}	
	pMainFile->deleteThis();
}

Implementing in gameinfo.txt

Now you can mount content by adding something like this after the ToolsAppId:

AdditionalContentId 220 //HL2
AdditionalContentId 240 //CS Source
AdditionalContentId 280 //HL Source
AdditionalContentId 320 //HL2 Deatmatch
AdditionalContentId 340 //HL2 Lost Coast
AdditionalContentId 360 //HL Deathmatch: Source
AdditionalContentId 380 //Ep1
AdditionalContentId 400 //Portal
AdditionalContentId 420 //Ep2
AdditionalContentId 440 //TF2

Don't forget to add the relevant SearchPaths too.

Note:With Left 4 Dead Valve switched from the GCF file system to the VPK format. GCF engine branches cannot mount VPK content, and the same vice versa.

Bugs

Really big numbers will crash the game with an Error-Dialog by Valve. You could check if the value is within a certain range to stop this from happening, but I think the user will get by himself that this value cannot be mounted.

Confirm:filesystem->MountSteamContent returns FILESYSTEM_MOUNT_OK, even if the content is not available. There's nothing you can do about it, apart from poking some guy from Valvesoftware.

See also