Preview build for the upcoming update (Patreon)

I’ve got some interesting news! But first, attached is a preview build for the upcoming update. There are quite a few changes, so I’d like to test it for another day or so before releasing it publicly, but it should be pretty stable now. Here are the main changes:

• CSP got configs that are applied to all cars and all tracks. With them, rain tyre patterns now can be applied to all cars that need them.

• Rain tyres physics parameters adjusted and fixed.

• Loading should be smoother and faster, especially with new loading caching option (I’ve added profiler which shows where time is spent exactly, and what parts were causing freezes; more optimizations are coming soon).

• All crash messages were reworked to be more informative and helpful.

• With extended physics it’s possible now to redefine collision parameters, such as friction, bounciness or softness, for both cars and tracks with new extended tracks physics (particularly helpful to make heavy cars more stiff — original AC collisions are a bit soft to simulate a bit of a flex, but those settings work well only for more lightweight cars). Also, new option now allows to tweak online collisions, helpful for cars with mass vastly different from 1000 kg (documentation is coming soon).

• And, as usual, a bunch of fixes and optimizations. Here’s the full list of changes.

And there is another potential breakthrough, still in testing stage, but I think it seems to work. Have you ever noticed an issue with large tracks where FFB would get messy, especially for cars moving slow or standing still? That precision issue which happens because AC uses 32 bit floating point numbers, and with large coordinates they start to lose accuracy. To fix it, I spent days trying to swap AC’s underlying physics engine (AC uses ODE to handle rigid bodies, joints and collisions) with something more modern capable of dealing with such issue. I tried PhysX, Bullet and Newton Dynamics, but unfortunately couldn’t get any of them to run reliably with the way AC uses its physics engine. 

Well, it turned out the solution might be much more straightforward. Now I simply swapped ODE with ODE complied with double precision, and it seemed to have helped, although at some performance cost (on my PC in a race with 55 cars it seemed to increase CPU load by 5%). And looking at how AC configures those slightly soft car-track collisions, I think it was the only option all along: it’s unlikely that the exact same behavior could be recreated with a different physics engine, and considering how often some open wheelers touch ground, those collision parameters seem to be crucial.

Whole thing is still at testing stage, disabled by default and not available online for safety reasons (just in case I missed something and it can give an unfair advantage). You can enable it in General settings:

If you’re driving on large tracks, such as Nordschleife or Shuto, please give it a test and check if it would help. Although please note, visual issues would still be present, I’ll work on fixing those in near future (I thought of fixing it before, but didn’t want to spend time on it before figuring out a way to improve physics part).

Thank you so much for all the incredible support! For the next part, I’ll work on adding protected RainFX configs, fixing remaining RainFX bugs and improving the way it looks, and, of course, working on fixing visual shaking caused by the same precision problem. Also, there might be a way to speed up physics at least a little bit, to try and compensate for that extra cost from double precision physics.