[Tool Released] TDU gravity modding

[Katie Cookie]

With the help of ghidra and x86dbg, I think I found a modifier on the game exe for changing non-hardcore vehicle gravity

While the game exe is sadly stripped of symbols, by searching for "gravity" strings, there exists a "Gravity Coef" string, around where the game seems to set boundries for car handling during game start such as "Gravity Height Max", for the non hardcore car physics engine

The "Gravity Coef" is taken from a static variable, and that static variable is set from a 4 byte floating point constant at 0x00f8a21c (memory address in ghidra, on a drm-less 1.66a exe)

Patching that constant before it is used can effect car gravity when a wheel is lifted off the ground; the current value is 1.0, setting it to 0.0 leads to what it seems to be pretty reasonable gravity instead of having artificial down force pushing the car back to the floor, -10.0 sends the car upward which then respawns on the ground

It might be possible to change that with cheat engine as well, I'm not familiar with cheat engine however but it has to be set very early on during game initialization, before the value is set to car handling (that happens even before the game window is shown)

I'll play with that a little bit in a few races then maybe post a non-hardcore gravity patched exe

Edit: Gravity patching tool can now be found at, a list of related memory offset can be found at https://github.com/Kethen/TDU_normal_mode_gravity_changer/blob/main/memory_offsets.md

 

Edited May 8, 2023 by Katie Cookie