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fhDOOM is one of my little side projects. I am working on this because its fun and a great learning experience. Its interesting to explore the code and to test out how such an old game can be improved by new features and more modern techniques. I have no plans to make a real game or something like that with it. Using Unity, Cry Engine or Unreal Engine might be a better choice for that anyways.


  • Keep it easy to build
    • simple build system
    • compiles with modern compilers
    • minimal dependencies
  • Keep the original game working, all of it!
    • the game itself
    • the expansion pack Resurrection of Evil
    • the tools
  • Stay true to the original game. Enhancements are fine, as long as they don't look out of place or destroy the mood of the game.
  • Support for Windows and Linux

Similar Projects

There exist other forks of the DOOM3 engine and even id software released a modernized version of DOOM3 and its engine as "DOOM 3 - BFG Edition".


  • CMake build system
  • Compiles fine with Visual Studio 2013 (you need to have the MFC Multibyte Addon installed) and Visual Studio 2015
  • Replaced deprecated DirectX SDK by Windows 8.1 SDK
  • Use GLEW for OpenGL extension handling (replaced all qgl* calls by normal gl* calls)
  • Contains all game assets from latest official patch 1.31
  • OpenGL 3.3 core profile
  • Fixed function and ARB2 assembly shaders are completely gone
  • Re-wrote everything with GLSL
  • Game and tools
  • Soft shadows via shadow mapping
  • Alpha-tested surfaces can cast shadows
  • Configurable globally as a default (useful for original maps) and for each light individually
    • Softness
    • Brightness
  • Shadow mapping and Stencil Shadows can be freely mixed
  • Poisson sampling
  • parallel/directional lights use cascade shadow mapping
  • modified 'dmap' compiler to generate optimized occlusion geometry for shadow map rendering (soft shadows)
  • occlusion geometry is stored in a separate .ocl file (.map and *.proc are still the same)
  • ocl file optional, maps without ocl file work just fine (at the expense of performance)
  • dmap option 'exportObj' will export occlusion geometry to obj files
  • fhDOOM includes ocl files for all maps of the original game
  • Soft particles
  • Parallax occlusion mapping (expects height data in the alpha channel of the specular map)
  • Added support for Qt based tools
    • optional (can be excluded from the build, so you are not forced to install Qt to build fhDOOM)
    • Implemented some basic helpers
      • RenderWidget, so the engine can render easily to the GUI
      • several input widgets for colors, numbers and vectors
      • utility functions to convert between Qt and id types (Strings, Colors, etc.)
    • re-implemented the light editor as an example (+some improvements)
      • useable ingame and from editor/radiant
      • cleaned up layout
      • removed unused stuff
      • added advanced shadow options (related to shadow mapping)
      • show additional material properties (eg the file where it is defined)
  • Several smaller changes
  • Detect base directory automatically by walking up current directory path
  • Added new r_mode's for HD/widescreen resolutions (r_mode also sets the aspect ratio)
  • Set font size of console via con_fontScale
  • Set size of console via con_size
  • Minor fixes and cleanups in editor code (e.g. fixed auto save, removed some unused options)
  • Renamed executable and game dll (the intention was to have fhDOOM installed next to the original doom binaries. Not sure if that still works)
  • Moved maya import stuff from dll to a stand-alone command line tool (maya2md5)
  • Compile most 3rd party stuff as separate libraries
  • Fixed tons of warnings
  • image_usePrecompressedTextures is 0 by default, so HD texture packs (like Wulfen) can be used more easily.

see also for complete history of all changes.


Shadow Mapping

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Soft Particles

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Parallax Occlusion Mapping

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Enhanced Light Editor (Qt based)

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All Screenshots were taken with HD textures installed (Wulfen, Monoxead, xio).


  • Download Binaries here:
  • The recommended way to install fhDOOM is to unpack fhDOOM into its own directory and copy only those files from the original Doom3 that are needed:
    • Extract zip to a location of your choice (e.g. c:\games)
    • Copy 5 files from the original DOOM3 (CD or Steam) to base directory of fhDOOM (e.g. c:\games\fhDOOM\base):
      • pak000.pk4
      • pak001.pk4
      • pak002.pk4
      • pak003.pk4
      • pak004.pk4
    • Start game by clicking on fhDOOM.exe
    • Don't forget to change the game's resolution (fhDOOM does not yet select your native resolution automatically).
  • Alternatively you can unpack the downloaded zip directly into an existing Doom3 installation.
    • As mentioned before, fhDOOM contains the last official patch (1.31), so some files (pak00[5-8].pk4 and Default.cfg) will be overwritten if this patch is already installed (e.g. you installed patch 1.31 manually or installed the game via Steam). Skipping these files should be fine as well.
    • fhDOOM is usually not tested in combination with other mods, so if you have other stuff installed all bets are off.
    • If you run into any issues, please try the clean and recommended installation as described above.
    • Future releases will very likely include a variant without the additional files from patch 1.31 to make this a bit easier.


Q1. Are Mods supported?

Yes! Mod support is pretty much the same as in vanilla Doom3 1.3.1 (only difference: game dll is named 'fhGame-x86' instead of 'gamex86').

Q2. Is fhDOOM compatible with mods for vanilla Doom3 1.3.1?

It depends. Pure content mods containing only textures, scripts, maps and such things should work just fine (only exception: custom ARB2 shaders won't work). Mods that come with a compiled game dll (gamex86.dll on windows, on linux) won't work. Those game dlls must be recompiled for fhDOOM.

Q3. Can i use SikkMod with fhDOOM?

No, because SikkMod is based on ARB2 shaders (see Q2).

Q4. Can i use HD texture mods (Wulfen, Monoxead, etc.) with fhDOOM?

Yes (see Q2).

Q5. How do i (re)compile a mods game dll for fhDOOM?

Unfortunately that's currently not that easy. You have basically two options:

  1. If you don't care about existing installations of officially released fhDOOM binaries, you could just clone the latest fhDOOM version from github. You apply your changes to the game code and distribute the whole thing (executable and game dlls).
  2. You clone the fhDOOM version from github that matches the latest official binary release. You apply your changes to the game code and distribute only the game dll to the user (the user must have fhDOOM installed). Pretty much like vanilla Doom3 1.3.1.

Both options are far from being good, but since i am working for the most part on the engine itself and not on the game code, i never felt the need to improve this. If you want to make a mod and need to compile your own game dll, let me know. If there is enough interest in better support for this, i will set up and release some kind of SDK to easily compile only the game code.

Q6. Does multiplayer work?

I suppose it does... but i don't know for sure. Feel free to test it out and share your findings :)


fhDOOM added and changed a couple of cvars. This list of cvars might be interesting:

  • r_mode <0..15>: set resolution and aspect ratio. Resolution can also be set via GUI.
    • 0..8: (unchanged, 4:3)
    • 9: 1280x720 (16:9)
    • 10: 1366x768 (16:9)
    • 11: 1440x900 (16:10)
    • 12: 1600x900 (16:9)
    • 13: 1680x1050 (16:10)
    • 14: 1920x1080 (16:9)
    • 15: 1920x1200 (16:10)
  • r_shadows <0|1|2>: default shadow mode, can also be selected via GUI.
    • 0: force shadows off
    • 1: use stencil shadows
    • 2: use shadow mapping
  • r_specularScale : scale specularity globally
  • r_specularExp : sharpness of specular reflections
  • r_shading <0|1>: shading model
    • 0: Blinn-Phong
    • 1: Phong
  • r_pomEnabled <0|1>: enable/disable parallax occlusion mapping, requires special specular maps with height information in alpha channel
  • r_pomMaxHeight : adjust max displacement
  • r_smBrightness : adjust default brightness of soft shadows
  • r_smSoftness : scale default softness of soft shadows (higher values will lead to artifacts)
  • r_smPolyOffsetFactor : depth-offset of shadow maps (increasing this will fix artifacts from high softness, but will also increase light bleeding)
  • r_smForceLod <-1|0|1|2>: set lod (quality/size) of shadow maps for all lights
    • -1: choose dynamically based on light size and distance from viewer
    • 0: high quality (1024x1024)
    • 1: mid quality (512x512)
    • 2: low quality (256x256)
  • r_smLodBias <0|1|2>: apply lod bias to lights to reduce quality without forcing all lights to the same lod.
  • r_smUseStaticOcclusion <0|1>: enable/disable static occlusion geometry from ocl files
  • r_glCoreProfile <0|1>: enable/disable opengl core profile (requires full restart of the game)
  • r_glDebugOutput <0|1|2>: OpenGL debug messages, requires core profile
    • 0: No debug message
    • 1: async debug messages
    • 2: sync debug messages
  • con_fontScale : scale font size in console
  • con_size : scale console (not immediately visible, close and re-open the console to see it)
  • com_showFPS <0|1|2|3>: 0=Off, 1=FPS, 2=ms, 3=FPS+ms
  • com_showBackendStats <0|1>: show various backend perf counters
  • g_projectileLightLodBias <0|1|2>: reduce shadow quality from projectile lights, usually not noticable
  • g_muzzleFlashLightLodBias <0|1|2>: reduce shadow quality from muzzle flashes, usually not noticable


  • The maps of the original game were not designed with shadow mapping in mind. I tried to find sensible default shadow parameters, but those parameters are not the perfect fit in every case, so if you look closely enough you will notice a few glitches here and there
    • light bleeding
    • low-res/blocky shadows
  • Parallax Occlusion Mapping is disabled by default, because it looks weird and wrong in a lot of places.
  • Shaders from RoE expansion pack not rewritten yet
  • There was a time, where you could switch from core profile to compatibility profile (r_glCoreProfile). In compatibility profile, you were still able to use ARB2 shaders for special effects (like heat haze). This feature stopped working for some reason. Not sure if i will ever investigate this issue, i am fine with core profile.
  • The font size of the console is scalable (via con_fontScale), but the width of each line is still fixed (will be fixed later).
  • Doom3's editor code is still a giant mess
  • fhDOOM is 32bit only at this point
  • I already had a linux version up and running, but its not tested very well. I am currently focussed on windows.
  • I added support for Qt based tools purely out of curiosity. I have currently no plans to port more tools to Qt.
  • Other stuff on my ToDo list (no particular order):
    • Some ideas to improve render performance (related to shadow mapping). The engine runs pretty decent on my (fairly dated) machine, not sure if its worth the effort. Might change with more advanced rendering features.
    • Expose different sampling techniques (currently hard coded)
    • HDR rendering/Bloom
    • Tesselation/Displacement Mapping
    • Multi threading
    • Hardware/GPU skinning
    • Port deprecated MBCS MFC stuff to unicode, so you don't need that MBCS Addon für VS2013.
    • Doom3 contains a very early and simple form of Megatexturing. Might be interesting to re-enable that for modern OpenGL and GLSL.
    • 64bit support would simplify the build process on linux (totally irrelevant on windows, the actual game doesn't really need that much memory...)
      • Get rid of ASM code. Rewrite with compiler intrinsics? Not sure if its worth the effort... the generic C/C++ implementation might be sufficient (needs some testing)
      • Get rid of EAX stuff
    • Look into Doom3's texture compression and modern alternatives. Does the wulfen texture pack (and others) really need to be that big? How does it effect rendering performance? Pretty sure it could improve loading times...
    • Render everything to an offscreen buffer
      • simple super sampling
      • fast switching between different r_modes
      • simplifies messy fullscreen switch
  • i am pretty sure i forgot a lot of things, so you might discover more things that are pretty hacky or not working at all ;)

Building fhDOOM

Build Status


  • Visual Studio 2013 or Visual Studio 2015 or Visual Studio 2017. Community versions are just fine, but VS2013 needs MBCS-Addon.
  • cmake 3.2 (make sure cmake.exe is in your PATH)
  • Windows 8.1 SDK
  • optional: Qt 5.4 (32bit)
  • optional: Maya 2011 SDK (32bit)


  • Clone repository
  • Just as with the regular installation, copy these files from the original DOOM3 game into the base directory of your local repository (git will ignore them):
    • pak000.pk4
    • pak001.pk4
    • pak002.pk4
    • pak003.pk4
    • pak004.pk4
  • Run cmake_msvc201x.cmd to generate
    • if you want to build with Qt tools enabled, there are two ways to tell cmake where Qt is installed:
      • run cmake_msvc201x.cmd -DQTDIR=<QTDIR>
      • or set an env var in windows: QT_MSVC201x_X86=<QTDIR>
      • <QTDIR> must point to your Qt installation so that <QTDIR>/bin contains all the Qt binaries (dll and exe files).
      • Please keep in mind that fhDOOM needs a 32bit build of Qt
  • Compile fhDOOM from Visual Studio
    • Debug and Run fhDOOM directly from Visual Studio
    • fhDOOM will pick up the base directory in your repository automatically
  • The zip file from a fhDOOM release contains a pk4 file pak100fhdoom.pk4. This file contains all the new shaders and required asset files. You may have noticed that this file cannot be found in the git repository. For easier editing all asset files are loosely placed in the base directory of the repository. You can directly edit these files or add new ones and fhDOOM will use them. These files are automatically packed up into pak100fhdoom.pk4 when you generate a distributable zip file (e.g. for release), see below for details.
  • Generating distributable zip files: There are three special build targets that generate distributable zip files:
    • dist: generates a zip file that contains fhDOOM and all required files from the official 1.31 patch (this is what is usually released)
    • dist_nopatch: same as dist but without the files from the 1.31 patch
    • sdk: generates a SDK to build only a game dll for fhDOOM (this is currently not used, not sure if its still working)


Modernized DOOM3/idTech4 engine: ported to modern OpenGL (core profile), enhanced visual effects, improved performance, improved editor, more to come








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