Stuntman - FPU rounding errors for AI pathing

[Souzooka]

PCSX2 version:
PCSX2 1.5.0-dev3032

• Notes:
  In Stuntman, AI paths are slightly erroneous due to FPU rounding issues; the game is unable to be finished due rounding issues. This can be witnessed in any level with a car the player is made to follow. Specifically, in the fourth level of the game, the player follows a lead car using a police car. On the "Chop/Zero" FPU rounding mode, the lead car fails to make a corner in the level, softlocking the level. Changing the rounding mode to "Nearest" allows the car to make it past this corner, but it fails the very next turn.

How to reproduce the issue:
Start a new career in Stuntman, finish the first three levels, then attempt to finish the fourth level.

Last known version to work:
While the game is marked playable, there is no evidence that the game was ever checked that it was able to be completed. The game is pretty resource-intensive, and it is more likely that the first level was tested at most by most testers.

Attached is a picture of the lead car failing to make a turn on the "Chop/Zero" setting.

[Souzooka]

I attempted to try this PR and while the AI gets even further on interpreter, he still fails a turn later.

Try to set also VU clamping/rounding. This game use both FPU, and VU to calculate physics there.
Problematic calculations results are from in game functions dyForwardDynamics, and dyStepRunge1 to dyStepRunge5 (0x211E60 to 0x2127AC for US release).

[LoStraniero91]

This also happens in Driv3r (and probably Driver: Parallel Lines).
Could be the same issue since all of them were made by Reflections.

[refractionpcsx2]

I know it probably isn't fixed, but can this be tested on a recent master to see if it's any better?

Yes, issue is still present on latest master.

Edit:
I made few tests, and looks like game don't like hardcoded DIV/SQRT/RSQRT nearest rounding on FPU. Although removing it help only little bit, you still can't finish level that way. That's for recompiler, interpreter seems to be broken even more on that game.

Here are settings, and explanation where you can get with them.

FPU / VU (All test done with removed hardcoded FPU nearest hack)
Negative / Zero
Best result, car crash at the wall in the end.

Nearest / Zero
Result like on Souzooka picture.

Positive / Zero
Crash earlier, car goes too much on right side.

Negative / Positive or Nearest
Close to first picture, but crash to wall at left little bit earlier than on VU Zero. There is no way to test properly VU negative rounding because that mess VU1, and picture. But setting it for moment make car path worse when we set it back. Tried also negative div hack, seems to have no effect. So that suggest sqrt/rsqrt nearest rounding make it bad.

Edit2:
Looks like i missed that pcsx2 use different file for doubles, and didn't removed hack there previously.
So results stay as above, but now we can get to "best result" even on Zero/Zero rounding. Still no way to finish stage.

[arienap]

I did some more testing with the PAL version of this game and compared the behavior of the AI car to an actual PS2.
I used a later level (Woopin and a hollerin) and by setting the EE rounding to nearest I get the AI to behave closest to actual PS2 AI. EE rounding to zero, positive or negative make the AI drift further sooner from the game on PS2. For all other settings (VU rounding and EE/VU clipping) I could not see the effect on the AI car.
Tested with v1.7.0-dev-546-g64010cf79 (latest GIT build).
Game plays nicer on PCSX2 than on my PS2+TV, I think because of the better analog sticks of the Xbox360 pad combined with less input lag.

areinap, if you can send me a save of your game to the Woopin and a hollerin mission as well as a savestate before the car get stuck I would appreciate it, thanks.

[arienap]

Stuntman_debug.zip
I have uploaded a memory card with the 100% completed career from my PS2.
I have only completed the PAL version and the debugging was also done with the PAL version.
You can try the Woopin mission (nr.2 corkscrew) by loading the game "Arie" from the main menu and then go into the filmography in the career menu. For your convenience, I attached a save state of doing just exactly that. The save state is at the beginning of the mission, the cars path is affected right from the start. By changing the EE FPU settings you must restart to see the full effect (the path of the cars drifts earlier / later).

Thanks a lot for uploading booth the memorycard and save state, I will look into the game.