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BUILD-SYSTEM.adoc

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Build system

This is an explanation of the functioning of the Freedoom build system.

Overview

Freedoom is built using 'deutex', which is a command-line tool for automated building of Doom WAD files. However, multiple different WAD files are built from the Freedoom material. Therefore, the Freedoom build system is more complicated than a “normal” deutex build would otherwise be.

A top-level Makefile controls the build system and executes the appropriate commands to generate the output WAD files. Various intermediate files are generated in the process by scripts. The following diagram illustrates the process:

        buildcfg.txt     lumps/textures/textures.cfg
             │                       │
             │                   ┌───┴────┐
             │                   │  cpp   │
             │                   └───┬────┘
             │                       │
             │             ┌─────────┴────────┐
             │             │  build-textures  │
             │             └──┬────────────┬──┘
             │                │            │
             │        pnames.txt    texture1.lmp, pnames.lmp
             │                │            │
         ┌───┴────┐           │            │
         │  cpp   ├───────────┘            │
         └───┬────┘                        │
             │                             │
   ┌─────────┴──────────┐                  │
   │ wadinfo─builder.py │                  │
   └─────────┬──────────┘                  │
             │                             │
        wadinfo.txt                        │
             │                             │
         ┌───┴────┐                        │
         │        ├────────────────────────┘
         │ deutex │
         │        ├───────── all other source files (graphics, etc)
         └───┬────┘
             │
      wads/(wadname).wad

Output WAD files

The following are the resulting WAD files generated by the build system:

  • freedoom1.wad: Phase 1, the Ultimate Doom IWAD file.

  • freedoom2.wad: Phase 2, the Doom II IWAD file.

  • freedm.wad: FreeDM IWAD file, containing deathmatch levels

Source configuration files

Master configuration file (buildcfg.txt)

deutex is configured using a configuration file typically named wadinfo.txt. In the case of Freedoom, multiple different WADs are built from the common material, with slightly different settings for each. Therefore, a 'master configuration file' named buildcfg.txt is used to generate configuration files for each individual WAD to build.

The buildcfg.txt file is processed using a Python script named simplecpp. This processes files with a syntax similar to the cpp tool (C Preprocessor). Variables are defined on the command line, based on the type of output target desired:

  • DOOM2: Build for a Doom II WAD.

  • DOOM1: Build for a Doom I WAD.

  • ULTDOOM: Include episode four levels.

Texture configuration file (lumps/textures/textures.cfg)

The texture configuration file is used to generate the texture lumps. These are texture1.lmp (texture directory), pnames.lmp (list of patch names) and texture2.lmp (Doom I only). They are generated by the build-textures script; deutex’s internal texture builder is deliberately not used for compatibility reasons.

Similarly to the build configuration file, different textures are included depending on the output WAD type. The file is passed through the simplecpp script to include the appropriate textures. Command line variables are defined based on the desired build settings:

  • DOOM1: Include textures that only exist in Doom I.

  • DOOM2: Include textures that only exist in Doom II.

  • ULTDOOM: Include textures that only exist in Ultimate Doom.

  • FREEDM: Include textures that are needed for FreeDM.

Note that DOOM1 and DOOM2 are not mutually exclusive, and the default for a Doom II build is to include all of the textures for both.

Generated files

The following files are generated automatically by automated scripts during the build process.

Texture files

texture1.lmp is a binary file that contains the texture definitions and is built by the build-textures script from lumps/textures/textures.cfg as a template.

pnames.txt contains a list of all of the patches used in the texture definition file (texture1.txt). It is generated as an output by the build-textures script.

Multiple sets of these files are generated with different configurations for each IWAD file.

Subdirectory WAD File CPP Variables

lumps/textures/phase1/

freedoom1.wad

DOOM1, ULTDOOM

lumps/textures/phase2/

freedoom2.wad

DOOM1, DOOM2

lumps/textures/freedm/

freedm.wad

FREEDM

wadinfo.txt

This is the auto-generated deutex configuration file, built from the buildcfg.txt template. It includes the PNAMES list from pnames.txt.

Several different wadinfo.txt files are generated for the different WAD files that are built:

Filename WAD File CPP Variables

wadinfo.txt

Resource WAD files

DOOM2

wadinfo_phase1.txt

freedoom1.wad

DOOM1, ULTDOOM

wadinfo_phase2.txt

freedoom2.wad

DOOM2

wadinfo_freedm.txt

freedm.wad

FREEDM

wadinfo.txt differs from the others in that the '-dummy' option is not passed to the wadinfo-builder.py script.

Auxiliary scripts

The build system uses a number of auxiliary scripts in order to generate the necessary configuration files for the build. These are written in Python.

simplecpp

This script implements a subset of the syntax of the C preprocessor. It accepts #ifdef …​ #endif blocks to conditionally include sections of the input file in the output file. This is used when generating the wadinfo.txt and texture1.txt files to conditionally include certain resources depending on the type of WAD file being built.

The simplecpp script is used in preference to the actual cpp preprocessor, firstly so that it is not necessary to install cpp, and secondly because processing with cpp can alter the layout of the output file.

wadinfo-builder.py

This script processes the wadinfo.txt used to build the WAD file, and identifies resources specified in the file that do not yet exist. This is to deal with the fact that Freedoom is incomplete and not all of the material needed for a complete WAD has yet been submitted.

Different strategies are used to cope with these missing resources depending on the WAD file being built. For IWAD builds, dummy resources are substituted for the missing resources (this mode is activated using the -dummy command line parameter). For resource WAD builds, the missing resources are commented out in the output file so that they are missing from the WAD that is built. This is the default behavior.

build-textures

This script processes the texture file (texture1.txt) and outputs the binary texture lumps texture1.lmp, texture2.lmp and pnames.lmp.

Also output from the build-textures script is a file named pnames.txt which is simply a text file containing the patches listed in pnames.lmp. This is included in the wadinfo.txt file so that all patches listed by the texture directory are automatically included in the IWAD with no need for manual configuration.

textgen

Found in graphics/text, this script generates various graphics files that are used in the Doom menus and intermission screen. It reads level names from the dehacked lumps.

playpal.py

Found in lumps/cph/misc-lumps, this script builds the PLAYPAL lump which contains the 256-color palettes used for special effects (injured “red” flash, the green “radiation suit” effect, etc.)

colormap.py

Found in lumps/cph/misc-lumps, this script builds the COLORMAP lump that is used for the diminished lighting within the game. This script is also reused to generate additional colormaps that can be used for special effects. It has a number of command line options that allow it to do various different colorizing and “fog” effects.

mkgenmidi

Found in lumps/genmidi, this script builds the GENMIDI lump used for OPL MIDI synthesizer playback. The inputs for this script are a collection of instrument files that are in the standard SBI format for OPL instruments. This lump is essential if you want to play using a classic Adlib or Soundblaster card; these are emulated by several source ports and some people still like to play using emulated OPL for the authentic retro feel.

gen-ultramid

Found in lumps/dmxgus, this script builds the DMXGUS lump used for GUS MIDI playback. The GUS (Gravis UltraSound) card was a gaming sound card popular in the '90s. As with the GENMIDI lump, few people are still using a real GUS card nowadays, but several source ports emulate them and require this file.

deutex

'deutex' is the tool used to generate the WAD files. It processes a file typically named wadinfo.txt, reading files from the following directories to generate the WAD:

  • flats: Floor and ceiling textures.

  • graphics: Graphics for the menu, heads up display and status bar, etc.

  • levels: The levels. Files are named eg. map01.wad or e1m1.wad for Doom II and Doom I levels, with FreeDM levels named eg. dm01.wad.

  • lumps: Miscellaneous lumps.

  • musics: Music files, in MUS or MIDI format.

  • patches: Patch graphics that are used to compose wall textures.

  • sounds: Sound effects, in WAV format.

  • sprites: Graphics for the in-game sprites (monsters, power-ups, weapons, decorations, etc.)

  • textures: Texture definitions.

Idiosyncrasies

deutex is an old tool and has various quirks that must be worked around. Some of them are listed here.

  • deutex does not allow the exact path to the texture1.txt file to be specified in the configuration file; this used to be a problem but the Freedoom’s texture lumps are now built using a custom script.

  • deutex requires an existing IWAD file in order to build WAD files, and includes the contents of the TEXTURE1 lump from the IWAD in any TEXTURE1 lumps it generates. To work around this, a “dummy” IWAD file containing an empty TEXTURE1 lump is contained inside the dummy directory.