Strange AI behavior with older VRC mods

[Gabor Edelmayer]

Hey guys, I'm using the latest CSP Preview build and noticed strange AI behavior when racing against older VRC content (Formula NA 99 and 2000s protos). The AI do 3 weird things that mostly only happen with these mods:

1. They don't understand track limits and often drive off track. This applies to both kunos tracks (even with custom AI files) and mod tracks. For example, at Laguna, they go in the sand and all crash at the same corner, or crash into the wall on corner entry on a street course.
2. The AI crash/spin in a corner and the car just stays stopped there for a long time (10+ mins). The cars are usually off track but it is still quite annoying. This is not exclusive to these cars but happens with other mods, so I'm guessing this is CSP related.
3. Some AI cars drive around the track at very slow speed (something like 50 kph or less) for some reason. Sometimes they have visible damage and drive around sometimes there is no damage. I have only seen this with VRC cars.

Based on my testing issue 1. and 3. do not happen with kunos cars and other mods. Also new VRC stuff like the super tourers also seem fine. I'm not sure if this is some CSP issue or an issue with older content not liking new CSP stuff.
Any help to solve these issues would be greatly appreciated.

 

[Jayenn]

It might be CSP, as it modified some aspects of the AI, but that's easy to test: Just disable the entire "New AI behaviour" part of CSP in CM.

If that's not it it's usually either the AI brake hint or the Aero hint in the ai.ini file within data.acd. If you lower the BRAKE_HINT value the ai cars will brake earlier for turns. AERO_HINT tells the AI how much extra downforce the car generates to be able to calculate the speed it can take the turn at.

Those values might just be set too aggressively by the author of the mod. It's always hard to balance those values between the AI driving at their absolute maximum while still keeping 100% track compatibility.

 

[Gabor Edelmayer]

I think I might have managed to figure out what was causing the weird AI but I'll have to do some more testing later.
In CM I had 'use extended physics' ticked which the old VRC cars really don't like. After unticking it, the AI made less mistakes and did not all crash in the same corner. They still act a bit robotic so I'll try messing with the ai.ini file as you suggested. Is there a setting in there that dertermines how wide the AI can deviate from the ideal line as I still saw them going wide on corner entry on some corners (they kick up dust/hit the wall but luckily no more crashing though)?
As a side note; what excatly does 'use extended physics' do besides giving rain tyres (I think the ffb feels different too but I might just be imagining...) and why does it break the AI?