Gran Turismo 4 Modding Discussion

[Memesbro]

You would have to look up the exact details of whichever modifications you had made to your console to run copied games, but there's a decent chance it will bypass region checks. Anything I know about ways to modify PS2 consoles is 20 years out of date though.

I have made absolutely none

 

[Johnny Caisse]

Does the editor even run?
If it doesn't, then you'd need somebody else to help. I'm on an older Windows so may not be familiar with how it works on newer versions. The .zip file from https://github.com/Nenkai/GT4SaveEditor/releases should contain an executable, which is the editor itself. Extract the app before running it.
If it does open, then you'd need to extract the content of the Spec II save for the editor to modify.

Disclaimer: I play on PS2 and the following is how I modify my saves so PCSX2 may work differently (instructions from https://github.com/Nenkai/GT4SaveEditor/releases/tag/0.6.0 maybe helpful). Regardless, it's crucial to make a backup of the memory card file before continuing. I'd simply zip it. A corrupted save or MC file is on you from here on out.

A memory card file may contain saves of multiple games. A GT4OPB save is BASCUS-97436GAMEDATA so this is what you'd be working on.
1. Run MyMC: "Open MC1", open the .bin save file, select the BASCUS-97436GAMEDATA, "Export save". Leave the app open.
2. Run PS2 Save Builder: File, Open, open the exported .psu file, select both BASCUS-97436GAMEDATA and garage, right-click, Extract, save. Leave the app open.
3. Run Nenkai's editor and open the location where Builder extracted those 2 files to. Modify whatever you want, then save. I recommend saving to a different location in case your modification isn't compatible with the game because the editor was not updated for Spec II.
4. In Builder, delete both source BASCUS-97436GAMEDATA and garage, leaving you with the 2 icon files. Drag and drop both modified files to builder. Save as either AR MAX v3 (.max) or Code Breaker (.cbs) format. Exit when done.
5. In MyMC, delete the source save (Warning: this actually deletes the save from the MC file so check if you've made its backup), "Import to MC1", open either the .max or .cbs file. Note the updated "Last Modified" time. "Close MC1" after you're sure that the save has been applied. Exit when done.

I recommend to delete the exported .psu file from step 1 after you're sure that the modification is working. There is a bug with my MyMC copy where a future export doesn't overwrite an existing .psu.
You can also delete the 2 extracted files from step 2 or the saved files from step 3 after done with editing.
Regarding the editor, I noticed that modifying anything unavailable/removed in OPB/Spec II may glitch the game so I'd edit only what's needed and only an item at a time. Iirc, the "Withdrawn credits" breaks the cheat shortcuts.

Y-yeah... I'm sorry, I am clueless. TheAdmiester? Do you think you could please add a way to use something similar to paint change to reset cars that can't change colors like those that change colors can be resetted by changing paint? I'll be patient. It's okay too if it's not possible.

 

[60fpshacks]

I have made absolutely none

If you prefer to use DVD over loading games from solid-state devices, look up PS2 Free DVD Boot.

 

[VanessaMagick]

Does anyone know if the palette indicators... y'know, these things that show the colour of the car...

... can be changed at all? From the looks of it they don't have a bespoke texture. I've been enjoying making custom liveries for GT4 but can't figure out a way to change these to match.

 

[Memesbro]

If you prefer to use DVD over loading games from solid-state devices, look up PS2 Free DVD Boot.

I have an old PS2, I.e. the big boxy one

 

[Johnny Caisse]

Just wondering, would engine swap be possible at some point or is it like GT2 A-Spec Project where it's impossible?

If it ever was possible I wouldn't mind waiting.

 

[Dave A]

I would imagine it's possible in a convoluted way where you are essentially replacing the car with a different car with it's own different specs that include the new engine. But you'd lose any parts you've already bought for the car prior to the change. If it can be done, I would imagine it would be a bit like the paint shop feature that @TheAdmiester added.

 

[TheAdmiester]

I would imagine it's possible in a convoluted way where you are essentially replacing the car with a different car with it's own different specs that include the new engine. But you'd lose any parts you've already bought for the car prior to the change. If it can be done, I would imagine it would be a bit like the paint shop feature that @TheAdmiester added.

Effectively impossible as a freely swappable part, but in theory it would be possible in terms of adding a duplicate car with a pre-swapped engine, then having an engine swap menu where it goes "here you go, you've swapped your engine!" while it replaces the car behind the scenes. It would have to be manually set up per-car and runs the risk of making the game's database too big though.

 

[60fpshacks]

Just wondering, would engine swap be possible at some point or is it like GT2 A-Spec Project where it's impossible?

If it ever was possible I wouldn't mind waiting.

It's not impossible on GT2, at least with memory hacking. I made this code for GT2 1.0 USA some years ago, but never publicly posted it before now.

Car Garage Slot 10 Turbo Kit ID
801CD5AC 024A
I am not 100 percent sure, but I think this may be the (stage 4) turbo kit for the Mitsubishi GTO or the Toyota Supra JZA80.
Buy an Escudo Pikes Peak and put it in Garage Slot 10 you will have about 2000HP or more, or somewhere close to it. You may need to first buy a turbo kit (at least for other cars) so the game knows to check the value before you enable the code but I cannot be sure.

 

[TheAdmiester]

It's not impossible on GT2, at least with memory hacking. I made this code for GT2 1.0 USA some years ago, but never publicly posted it before now.

Car Garage Slot 10 Turbo Kit ID
801CD5AC 024A
I am not 100 percent sure, but I think this may be the (stage 4) turbo kit for the Mitsubishi GTO or the Toyota Supra JZA80.
Buy an Escudo Pikes Peak and put it in Garage Slot 10 you will have about 2000HP or more, or somewhere close to it. You may need to first buy a turbo kit (at least for other cars) so the game knows to check the value before you enable the code but I cannot be sure.

To be fair there's quite a big difference between a memory hack and an actual in-game feature. Hybriding has been possible for decades across just about every GT, but a user-friendly feature as part of a mod is an entirely different story.

 

[TheKrzysiek]

How difficult would it be to edit which cars appear in each cup?

Each time I come back to this game, the main annoyance is having to reset the championships until I get a balanced grid, so it'd be nice to remove the cars that are a lot faster or slower than the rest.

 

[TheAdmiester]

How difficult would it be to edit which cars appear in each cup?

Each time I come back to this game, the main annoyance is having to reset the championships until I get a balanced grid, so it'd be nice to remove the cars that are a lot faster or slower than the rest.

It's not difficult but I don't think there are any particularly painful outliers anymore. Some of the particularly egregious ones like the Buick Special have already been moved, but outside of that I don't want to round off the AI variety too much.

 

[DRess_CODE]

Hello. Is there any way to find out the full list of changes in this mod, especially in the physics and characteristics of the car? The fact is that we're hosting GT4 competitions, and we want to strike a balance between those who play with and without the mod.

 

[Theufcveteran]

Hi, @TheAdmiester could I DM you? I am part of a modding team which has garnered a large following for our mod - that isn't the point, but it's more of that I wanted to say upfront that I am an experienced modder with proof, and that work a lot in hex, and I saw some of the things you were talking about with regards to limits and wondered if perhaps I could be of any use.

In this specific area, for the game that we mod, a PS3 game, guys on our team and I have been successful in breaking size limits.

However, is it simply that the DVD would get maxed out? On PS3 of course this isn't an issue since the game data can be installed to the HDD.

I understand that, of course, the game structure is wholly different to what I'm used to. But we have done things that even we didn't expect to figure out, and I am a dedicated learner. If the size problem is not one of physical disc space, but more of an unknown/tricky to figure out, perhaps I could be some help.

 

[TheAdmiester]

When I mention limits it's not in the sense of DVD space as I have almost 1GB left to play with, it's referring to the amount of memory the game can allocate which can't feasibly be changed.

 

[Theufcveteran]

When I mention limits it's not in the sense of DVD space as I have almost 1GB left to play with, it's referring to the amount of memory the game can allocate which can't feasibly be changed.

Ahh, gotcha. Forgive me because I swear I was just reading about what specifically was causing limits, but I must be remembering previous times I've looked through this thread. If I remember correctly, one example is that there are only a limited number of event slots, after which you run out of memory?

I take it that the game loads the whole event list in one go then? Do you know by chance where the game chooses how much memory to allocate where? I assume with a game like GT4, even if you did find it, there is very little free memory left.

You know much more than I about how GT4 works, and the limits of it. I only bring up the idea of adjusting the limits because there are things we on our team did not thing were really doable - granted, they didn't include memory allocation. But we did unlock file sizes for multiple types of files.

And I'm certainly not trying to say you don't know what you're doing or that you haven't already exhausted all options.

It's just in the off chance that something I have worked on could potentially be of use in terms of the methods used.

Would it be okay if I were to ask what the challenges are in terms of adjusting memory allocation?

 

[pez2k]

Do you know by chance where the game chooses how much memory to allocate where? I assume with a game like GT4, even if you did find it, there is very little free memory left.
...
Would it be okay if I were to ask what the challenges are in terms of adjusting memory allocation?

As far as I'm aware, it's all fixed static memory allocations, generally with everything allocated contiguously to avoid wasting space. That means that every reference to a particular piece of data is a hardcoded memory address in the executable which would need to be manually patched... plus anywhere it's referred to via an offset from something else, or is in an array that gets looped over.

A lot of the game data is also stored in a custom database ('specDB') which takes up a big chunk of memory by itself. It's too big to relocate, so expanding its allocation would mean moving everything else out of the way. Nothing is completely impossible, but it's the sort of level of work where it'd be 'easier' to fully decompile the whole game so that a compiler could sort it all out.

The older games also have other things that depend on specific memory layouts, for example a lot of GT2's data in memory is one massive fixed-size structure which simply gets copied to the memory card as a savegame, so changing allocations there also means heavy reworks of the saving and loading code, and breaking compatibility with existing saves. GT1 on the other hand will frequently overwrite seemingly free memory as it decompresses new executables for different parts of the game, with their own memory layouts. I wouldn't be surprised if GT4 has its own nasty snags like that too.

 

[Theufcveteran]

As far as I'm aware, it's all fixed static memory allocations, generally with everything allocated contiguously to avoid wasting space. That means that every reference to a particular piece of data is a hardcoded memory address in the executable which would need to be manually patched... plus anywhere it's referred to via an offset from something else, or is in an array that gets looped over.

A lot of the game data is also stored in a custom database ('specDB') which takes up a big chunk of memory by itself. It's too big to relocate, so expanding its allocation would mean moving everything else out of the way. Nothing is completely impossible, but it's the sort of level of work where it'd be 'easier' to fully decompile the whole game so that a compiler could sort it all out.

The older games also have other things that depend on specific memory layouts, for example a lot of GT2's data in memory is one massive fixed-size structure which simply gets copied to the memory card as a savegame, so changing allocations there also means heavy reworks of the saving and loading code, and breaking compatibility with existing saves. GT1 on the other hand will frequently overwrite seemingly free memory as it decompresses new executables for different parts of the game, with their own memory layouts. I wouldn't be surprised if GT4 has its own nasty snags like that too.

Thanks for the breakdown!

Yeah, memory allocation editing is beyond my scope. I have fiddled with save data, but haven't yet been able to accomplish what I am aiming for.

I would still like to learn more about it, though, memory allocation editing. Obviously there are hardware limits in terms of RAM and it seems like a mighty big job to adjust how it works - not sure how much upside there would be relatively speaking, but seems like a long old job.

What kind of data do GT games write to the memory card? Is it more than just variables, garage data, progression etc? I don't want to bring this thread too off-topic if we were to delve into GT1/2 more, but I would love to know more. I have been wanting to get into Gran Turismo modding for a while, the scene and the work done is fascinating.

If you are ok with it, and if talking more about non-GT4 modding would take this thread a little off-topic, I would really appreciate a DM about the workings of how the saving, etc functions, or a link perhaps if there is documentation on the process. I love reading about how a game works.

 

[pez2k]

What kind of data do GT games write to the memory card? Is it more than just variables, garage data, progression etc? I don't want to bring this thread too off-topic if we were to delve into GT1/2 more, but I would love to know more.

For GT2 it's all of the settings like language, volume levels, and default camera, all of the gamepad configuration like key bindings and calibration for every type of supported device, event completion for both Arcade and GT mode, event records (sector times, lap time, lap speed, car name, player name), license test records, machine test records, and finally the garage which includes a list of purchased parts and the current car setup for every one of the 100 slots. I have some unfinished code to document the save here.

I believe Nenkai's GT4 save editor is open-source too, so that should document at least some of how that game writes saves.

 

[Theufcveteran]

For GT2 it's all of the settings like language, volume levels, and default camera, all of the gamepad configuration like key bindings and calibration for every type of supported device, event completion for both Arcade and GT mode, event records (sector times, lap time, lap speed, car name, player name), license test records, machine test records, and finally the garage which includes a list of purchased parts and the current car setup for every one of the 100 slots. I have some unfinished code to document the save here.

I believe Nenkai's GT4 save editor is open-source too, so that should document at least some of how that game writes saves.

Thanks so much! Fascinating stuff. I will check Nenkai's save editor as well.

 

[Johnny Caisse]

Not too sure if it's intended but the Dodge RAM when fully tuned will slide brutally when going off-throttle. Currently only tested that way and with Racing Hard tires. Quick add: The torque is 50/50.

 

[DRess_CODE]

Hi. Sorry for asking, but what's up with Auto Union? First of all, there's no driver, the only thing left of him is his hands if you play in first person. Secondly, what's that image in the lower right corner? (The quality of the photo isn't very good, I know). This image is, at the very least, missing from the Nurburgring

 

[TheAdmiester]

Hi. Sorry for asking, but what's up with Auto Union? First of all, there's no driver, the only thing left of him is his hands if you play in first person. Secondly, what's that image in the lower right corner? (The quality of the photo isn't very good, I know). This image is, at the very least, missing from the Nurburgring

The Auto Union and Tank Car lose their driver models in some situations, there's no real way to figure out what it is but my best guess is that GT4 Online uses more memory than GT4 and deleting the driver model is one way the game tries to save memory before crashing.

The icon at the bottom right looks like a RetroAchievements notification, showing a preview of an achievement's icon if you're about to meet the conditions to unlock it. Not sure what the specific achievement is in this picture but it's not directly related to the mod anyway.