OpenTDU - Open Source port for Test Drive Unlimited 1 (2006)

opentdu · May 22

Hello everyone,

I have started a rather ambitious project: a decompilation of TDU1!
My current progress can be found on Github: https://github.com/opentestdriveunlimited/opentdu

What does it mean?

A decompilation project goal is to convert the assembly (machine code) of the shipped game into "readable" high level code (C++).

Why?

My main motivation is to provide a modern, cross-platform game client with quality of life improvement (e.g. remove framecapping for AI, remove WinAPI/D3D9 dependencies, fix existing security issues, etc.) as well as restoring cut content left in the game (e.g. pedestrians, boat tour, dirt system).

Roadmap

The goal is to get basic systems running first; then basic game modes (e.g. Sandbox or CarShowcase) and finally start working on FreeRide/implement the world streaming system/online/etc.

Stretch goals would be to have native mod support (directly integrated in the game), TDU2 asset support, state of the art rendering pipeline (move from the D3D9-era pipeline and use a fancy BRDF; photorealistic atmosphere rendering; etc.). But this is far far away, as decompiling a game is already a long term project (and a hobby project; I am not working full time on this!)

I will try to keep this thread alive with update/progress (so far I only have a blank window with a Vulkan context running; and I am actively moving and cleaning all my decompilation progress from Ghidra to my C++ project).

fvever · May 24

peds

boats

fuel

hawaii airport road not dirt

and we are good

andrey zyb · May 25

20 hours ago, camille_123 said:

peds

boats

fuel

hawaii airport road not dirt

and we are good

It looks like we're talking about restoring content that was cut out during game development.

PhanTimo01 · May 25

I wish you all the best, dude. That is quite ambitious. Here's hoping guys out here lend you a helping hand.

opentdu · May 26

On 5/24/2025 at 3:17 AM, camille_123 said:

peds

boats

fuel

hawaii airport road not dirt

and we are good

You can already get "grass as tarmac" if you extract the configuration files from the original executable (using the asset_extractor tool from the repository) and place the .ini next to your original TestDriveUnlimited executable (the original executable will use any decrypted .ini placed in the working directory)

andrey zyb · May 26

3 hours ago, opentdu said:

You can already get "grass as tarmac" if you extract the configuration files from the original executable (using the asset_extractor tool from the repository) and place the .ini next to your original TestDriveUnlimited executable (the original executable will use any decrypted .ini placed in the working directory)

Thank you for a truly ambitious project. I wish you good health and success in developing your project.

Djey · May 26

Yeah, good luck with it!

tdubot · May 27

It's Driving Ambition in TDU1

I'm really excited about your great work and wish you all the best!

andrey zyb · May 29

As I understand it correctly, this project should restore all the cut modes, including online racing, clubs, drive-ins, and a trading platform?

Djey · May 29

1 hour ago, andrey zyb said:

As I understand it correctly, this project should restore all the cut modes, including online racing, clubs, drive-ins, and a trading platform?

Those were not cut out during development, these are just features current server don't emulate.

andrey zyb · May 30

17 hours ago, Djey said:

Those were not cut out during development, these are just features current server don't emulate.

I understand that there is an online folder among the files on Github, so I thought that the client was adding missing online functions.

Edited May 30 by andrey zyb

opentdu · May 31

On 5/29/2025 at 11:45 PM, andrey zyb said:

I understand that there is an online folder among the files on Github, so I thought that the client was adding missing online functions.

I'm planning to reverse/decompile the client logic. It won't be compatible with Platinum online unfortunately (as the mod uses a proxy dll to hook the game). If one of the mod author is willing to share the source of the client I'd more than happy to support it natively

MeFisto94 · June 1

Hey @opentdu and @fvever!

It seems we're 3 persons trying to achieve something similar or at least having the same requirements!
That means if we're collaborating/open sourcing our findings, everyone could profit.

To summarize:

@fvever is working on getting TDU2 to run on PSP, right?

@opentdu Your motivation is outlined in this post, + it could help building Andraste Mods, I am just a bit confused by the mix of ground truth decompilation and a vulkan rendering instead of the DX9 first.

Then there's "us" (Me and the TDUniverse Team): We have a bare bones TDU1.5, which kind-of shares openTDU's goals, but not the way. The idea is to reimplement the game but without relying on decompilation and instead develop things from scratch in a modern way (and language, Rust). By that, I take the freedom to also implement things differently (maybe non p2p networking?). The name comes from the fact that it tries to bridge the gap between TDU1 and 2, too, reading both asset formats and databases but pulling the physics from TDU1 etc.

Besides that we've been working in tooling since a while, we have the non-public "Modding Studio" that converts a few file formats (into gltf, e.g., for a blender pipeline) and database editing capabilities (adding cars). It doesn't support world editing, though and especially not the havok collision shapes, e.g.

My suggestion would be that we at least work on a wiki documenting the file formats together, I guess we could already achieve 80% completion with our combined knowledge.

TDUniverse also has "TDUFileFormats", a C# reference implementation for those files, but I guess everyone of us is working in a different language anyway.

What do you think in general? WE can also provide a discord channel at TDUniverse and I guess Turboduck would do the same.

fvever · June 2

TDU 2 on psp ? you're crazy ! there are too much vertices ! Nope on PsVita and Switch maybe, and also working on a world editor at the same time for the PC Version and I agree 100% with you to make a discord chanel or something to discuss about tdu files

TDUZoqqer · June 6

wow that sounds amazing, good luck with it! wish i could contribute anyhow but eh, a spectator this time

opentdu · June 13

On 6/1/2025 at 2:08 PM, MeFisto94 said:

Hey @opentdu and @fvever!

It seems we're 3 persons trying to achieve something similar or at least having the same requirements!
That means if we're collaborating/open sourcing our findings, everyone could profit.

To summarize:

@fvever is working on getting TDU2 to run on PSP, right?

@opentdu Your motivation is outlined in this post, + it could help building Andraste Mods, I am just a bit confused by the mix of ground truth decompilation and a vulkan rendering instead of the DX9 first.

Then there's "us" (Me and the TDUniverse Team): We have a bare bones TDU1.5, which kind-of shares openTDU's goals, but not the way. The idea is to reimplement the game but without relying on decompilation and instead develop things from scratch in a modern way (and language, Rust). By that, I take the freedom to also implement things differently (maybe non p2p networking?). The name comes from the fact that it tries to bridge the gap between TDU1 and 2, too, reading both asset formats and databases but pulling the physics from TDU1 etc.

Besides that we've been working in tooling since a while, we have the non-public "Modding Studio" that converts a few file formats (into gltf, e.g., for a blender pipeline) and database editing capabilities (adding cars). It doesn't support world editing, though and especially not the havok collision shapes, e.g.

My suggestion would be that we at least work on a wiki documenting the file formats together, I guess we could already achieve 80% completion with our combined knowledge.

TDUniverse also has "TDUFileFormats", a C# reference implementation for those files, but I guess everyone of us is working in a different language anyway.

What do you think in general? WE can also provide a discord channel at TDUniverse and I guess Turboduck would do the same.

I'd be more than happy to contribute to any kind of document/wiki! I've made some rather interesting findings during the decomp that could help other modders projects (eg. the PC executable supports zlib compressed banks and has a bunch of helpers to reverse endianness; the game looks for DLCs in the savegame folders (and will install anything present in the marketplace subfolder; as long as the .big, .map and .xml inside the archive are valid)).

Rewriting everything from scratch sounds also pretty exciting, hope it will get somewhere

Edited June 13 by opentdu

andrey zyb · June 13

11 minutes ago, opentdu said:

I'd be more than happy to contribute to any kind of document/wiki! I've made some rather interesting findings during the decomp that could help other modders projects (eg. the PC executable supports zlib compressed banks and has a bunch of helpers to reverse endianness; the game looks for DLCs in the savegame folders (and will install anything present in the marketplace subfolder; as long as the .big, .map and .xml inside the archive are valid)).

Rewriting everything from scratch sounds also pretty exciting, hope it will get somewhere

I wish you good health and success in developing your project.

opentdu · June 14

I've also finally setup a CI to automatically create binaries for Windows (will add Linux and macOS later). You can find those binaries on the release page: https://github.com/opentestdriveunlimited/opentdu/releases

While there is no client available yet, you can use the asset extractor binary to extract the .ini files from your original TestDriveUnlimited executable and tweak the configuration of your game (this is the same files as the ones existing in TDU2).

To use the extractor, copy the executable next to your TestDriveUnlimited.exe one and run it (./opentdu_assetExtractor -executable "./TestDriveUnlimited.exe"; using either Powershell or cmd.exe). The executable will extract .ini files (as well as DX9 shaders).

You can then run TestDriveUnlimited and use specific command line switches to use the extracted .ini.

For reference:

-game "./GamePC.ini"
-system "./SystemPC.ini"
-audio "./Audio.ini"
-devices "./DevicesPC.ini"
-replay "./Replay.ini"
-physics "./Physics.ini"

e.g. ./TestDriveUnlimited.exe -w -game "./GamePC.ini"

Edited June 14 by opentdu

andrey zyb · June 14

5 hours ago, opentdu said:

I've also finally setup a CI to automatically create binaries for Windows (will add Linux and macOS later). You can find those binaries on the release page: https://github.com/opentestdriveunlimited/opentdu/releases

While there is no client available yet, you can use the asset extractor binary to extract the .ini files from your original TestDriveUnlimited executable and tweak the configuration of your game (this is the same files as the ones existing in TDU2).

To use the extractor, copy the executable next to your TestDriveUnlimited.exe one and run it (./opentdu_assetExtractor -executable "./TestDriveUnlimited.exe"; using either Powershell or cmd.exe). The executable will extract .ini files (as well as DX9 shaders).

You can then run TestDriveUnlimited and use specific command line switches to use the extracted .ini.

For reference:

-game "./GamePC.ini"

-system "./SystemPC.ini"

-audio "./Audio.ini"

-devices "./DevicesPC.ini"

-replay "./Replay.ini"

-physics "./Physics.ini"

e.g. ./TestDriveUnlimited.exe -w -game "./GamePC.ini"

Thank you for your hard work and ambitious project, I wish you success in further development and good health.

SpeedyService · June 16

Becoming open source... wouldn't that make it possible to make it playable on mobile devices without apps like winlator?

opentdu · June 18

On 6/15/2025 at 9:55 PM, SpeedyService said:

Becoming open source... wouldn't that make it possible to make it playable on mobile devices without apps like winlator?

As long as your phone supports Vulkan, yes. It should also be possible to support Emscripten/WebAssembly to make the game playable from a web browser (not sure if there is an audience for that tho )

MeFisto94 · Thursday at 11:10 AM

@opentdu @fvever So it took me a while but I finally made the basic wiki at https://wiki.tduniverse.org (https://github.com/TDUniverse/EdenTduWiki and npm run build to compile it locally).

I thought git is perfectly suited for such a wiki, compared to someone just hosting it, because that way the knowledge can't get lost that easily and we have better collaboration than on a github wiki alone. The file format is kind of markdown with extra features.

Currently all articles are stubs, I'll see what I can contribute over the next few days.

On 6/18/2025 at 3:23 AM, opentdu said:

As long as your phone supports Vulkan, yes.

There you'd probably have more success with WebGL2/openGL ES 3.0 though probably, for old phones and because Vulkan may otherwise tempt you to write a modern rendering backend

It's interesting anyway because due to both games having a "shared" xbox and pc renderer, you can see the xbox command list architecture, e.g. in tdu2 there's just a list where they append I think around 150 integers and sometimes some pointers and then number XY is means "bind index buffer", so you can probably abstract quite a bit, at least for those old APIs.

andrey zyb · Friday at 07:07 AM

opentdu_assetExtractor does not start, writes an incompatible version the same thing happens with opentdu_savedecryptor or opentdu does not work on all versions of windows and will this bug be fixed? my system is windows 7 x32 Will opentdu be optimized for 32-bit systems?

Edited Friday at 11:09 AM by andrey zyb

MeFisto94 · Friday at 07:51 PM

I now also created a public channel on our TDUniverse Discord (https://discord.tduniverse.org), link to the channel https://discord.com/channels/930226011071709194/1385708087708614797 to discuss reverse engineering, as suggested.

opentdu · Saturday at 03:59 PM

On 6/19/2025 at 4:10 AM, MeFisto94 said:

There you'd probably have more success with WebGL2/openGL ES 3.0 though probably, for old phones and because Vulkan may otherwise tempt you to write a modern rendering backend

It's interesting anyway because due to both games having a "shared" xbox and pc renderer, you can see the xbox command list architecture, e.g. in tdu2 there's just a list where they append I think around 150 integers and sometimes some pointers and then number XY is means "bind index buffer", so you can probably abstract quite a bit, at least for those old APIs.

I initially started with OpenGL 3.3 and ended up switching to Vulkan, as I was struggling to find a good library to translate dxso bytecode to GLSL. I might revisit this at some point if I need to save time.

On 6/20/2025 at 12:07 AM, andrey zyb said:

opentdu_assetExtractor does not start, writes an incompatible version the same thing happens with opentdu_savedecryptor or opentdu does not work on all versions of windows and will this bug be fixed? my system is windows 7 x32 Will opentdu be optimized for 32-bit systems?

I am not planning to support 32bit at the moment (as this will complicate streaming/resource management and file parsing).