Eternity Engine GFS Reference

Eternity Engine GFS Reference v1.01 -- 7/05/04

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GFS, or Game File Script, is a new method of adding multiple data files to Eternity at once with the use of only one command-line parameter. GFS syntax is extremely simple, and allows for more safety and semantic checking than do batch files or response files. GFS also doesn't exclude the use of any other command-line parameters in addition to itself, so you can override files added in a GFS with your own if needed. GFS is designed primarily for distribution along with modifications such as PCs, TCs, megawads, etc., to make it easier for users to play them without need for lots of command-line parameters.

Now that Eternity supports drag-and-drop file loading in windowed operating systems, users can also start your project by simply dragging a GFS onto Eternity. This is the absolute best way to load a project, perhaps aside from using a frontend. This functionality cannot be duplicated with batch or response files.

GFS uses the same libConfuse parser as EDF and ExtraData, written by Martin Hedenfalk, and therefore shares most of the same syntactic elements. GFS is free-form, meaning that whitespace is ignored and that other tokens' positions are irrelevant to their meanings. #, //, and /* */ comments are also supported, but are not very important for GFS files, so they will not be discussed in this document. To see thorough information on these elements of the syntax, see the General Syntax section of the Eternity Engine EDF Reference.

GFS supports long file names under operating systems other than DOS, but they must be enclosed in quotation marks if they contain spaces.

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Using GFS

To use a GFS file, use the -gfs command-line parameter, and give it an argument of one absolute file path to the desired GFS file. If the GFS file is in the executable's directory, it is not necessary for the path to be absolute, but otherwise GFS may not function properly if the path is only relative.

Example:

eternity -gfs C:\Games\AliensTC\atc.gfs

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How Files are Found

Normally, file names specified in a GFS are appended to the path of the GFS file. So if a GFS file is in C:\Games and specifies a file "superwar.wad", then "C:\Games\superwar.wad" will be added. This allows specification of subdirectories or the parent directory in a file name. It is recommended that GFS files provided with modifications allow the GFS to work in this manner.

Note that an IWAD file name will not have any path appended to it, so it should be an absolute path in all circumstances.

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Changing the Base Path

It is possible to alter the path which will be appended to WAD, DEH/BEX, CSC, and EDF file names by using the basepath variable. When basepath is set to a path, that path will be appended to those file names instead of the path of the GFS file. This allows GFS to be placed by the user into a directory other than that in which the other files exist. There can only be one basepath specification per GFS file. The last one found during parsing will be the one which is used.

This option is not generally useful to GFS provided with modifications, since authors cannot know how the user's file system is set up. This facility is present to allow users to create their own GFS files and keep them wherever they wish.

basepath, as mentioned above, does not affect the iwad specification, if one is present.

Example of Usage:

#
# Assume that Aliens TC 2.0 is in C:\Games\AliensTC, but this GFS is somewhere else
# (like in the port's directory, for example
#

# The files I want to load:

wadfile = alitcsf.wad
wadfile = alitcsnd.wad
wadfile = atclev.wad
dehfile = atcud19.bex

# The location where they're at, since the GFS file is not also there
# (note you could also use "C:\\Games\\AliensTC"):

basepath = "C:/Games/AliensTC"

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Adding WAD Files

A GFS can specify any number of wad files to load using the wadfile variable. WAD files will be loaded in the order in which they are specified.

A WAD file name should be a path which is relative either to the path of the GFS file, or to the basepath if it is specified.

GFS WAD files will be added before any other WAD files added via the command-line or specified in the configuration file, so that any WADs specified there can override those in the GFS.

Example of Usage:

wadfile = chextc.wad

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Adding DeHackEd/BEX Files

A GFS can specify any number of DeHackEd/BEX files to load using the dehfile variable. These files will be loaded in the order in which they are specified.

A DEH/BEX file name should be a path which is relative either to the path of the GFS file, or to the basepath if it is specified.

GFS DEH/BEX files will be added after any DeHackEd files added on the command-line. This allows command-line DeHackEd files to take effect before any changes made by GFS. However, DeHackEd lumps in WADs and any specified in the configuration file are still added last.

Example of Usage:

dehfile = chexq.bex

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Adding Console Scripts

A GFS can specify any number of console scripts to run using the cscfile variable. These files will be executed in the order in which they are specified.

A CSC file name should be a path which is relative either to the path of the GFS file, or to the basepath if it is specified.

GFS CSC files will be executed immediately after any that are specified via the configuration file.

Example of Usage:

cscfile = setvars.csc

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Specifying a Root EDF File

A GFS can specify the root EDF file to process by using the edffile variable. Only one root EDF file can be specified, so the last definition encountered will become the one that is used.

The EDF file name should be a path which is relative either to the path of the GFS file, or to the basepath if it is specified.

If the -edf command-line parameter is used, it will take precedence over this setting.

Example of Usage:

edffile = myroot.edf

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Specifying an IWAD

A GFS can specify the IWAD file to use by using the iwad variable. Only one IWAD file can be specified, so the last definition encountered will become the one that is used.

The IWAD file name should be the absolute path, including file name, of the IWAD. The basepath variable does NOT affect this file name, and the path of the GFS file will not be appended to it.

If the -iwad command-line parameter is used, it will take precedence over this setting.

This option is not generally useful to GFS provided with modifications, since they cannot know how the user's file system is set up. This facility is to allow users to create their own GFS files, or to edit existing ones, so that they can automatically be loaded without need to additionally specify the IWAD.

Example of Usage:

iwad = "C:/Games/DOOM/DOOM.wad"

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