Assetto Corsa Competizione: Sizeable Rewrite Underway - New Hotfix Released

Paul Jeffrey

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ACC Hotfix.jpg

Kunos Simulazioni look likely to be busy in the months ahead, having already released 'build five' of the sim and a new hotfix today, the team have confirmed a sizeable rewriting is underway.


When I say rewriting, what I mean by that is Kunos are hard at work revisiting some of the code created for ACC so far, in an effort to maximise how the software will be developed going forward in order to bring new content and features to the simulation more quickly, and with greater ease than is possible at this moment in time.

Unfortunately for Kunos, that means a lot of work 'behind the scenes' will need to be undertaken to achieve this change in direction, a feat that the small Italian development team are in no way underestimating how time consuming and difficult that might be. With the simulation still at such an early stage of development, it is excellent to see Kunos are so dedicated to bringing about the best experience they can with this Unreal 4 game engine, and yet more evidence that the makers of netKar Pro and Assetto Corsa fully intend this new title to be their biggest and best creation to date.

The full Kunos statement:
Having a look at the 0.5 release patch notes, you will find that most changes are either new content or physics related. Regarding gameplay elements – including Multiplayer features – we decided to opt for a different path, which may need some explanation for non-developers.

While developing software, especially games, you constantly invent patterns and concepts. When we built the ACC gameplay during 2018, we aimed for a certain way to write the game logic, including everything from session handling, race timing, laptimes, penalties and so on. Our solution had some amazing feats and ways of working, but we also had to learn that one of the disadvantages was making the development of Multiplayer features not as efficient as we had wished for. You may have noticed that although we met our roadmap targets on time in terms of content and features, several things involving Multiplayer were late. This is not really unusual or surprising; moving a whole development team to a new engine and framework required us to learn about the new situation as the project evolved (but we didn't know where this would happen, obviously).

In December we faced the choice to either keep proceeding like that, adding as little changes as necessary to achieve a stable 1.0 Multiplayer, and then never to touch it again.

The alternative route is a rewrite of (a lot of) the code to switch to concepts that support our current needs and the things we learned. The disadvantage is obvious; we'd have to spend a lot of work to change ACC without – seemingly – adding gamplay related features and fixes for a certain amount of time, however, the gain is a much more stable environment, where we can keep adding features and also speed up future development.

I can tell it's unusual to go for a rewrite, but it expresses our approach and our plans to go on, even beyond ACC 1.0. Technically speaking, a few developers forked off the codebase and worked day and night to do the re-coding, with the goal of bringing those improvements to the main code as soon as possible. The new features on the list therefore are there, but not in this build, and we most probably will also bring them one after another even looking beyond the 1.0 release, since the development will continue to bring our audience the 2019 Season update, and more. ;)

Being myself also responsible for ACC Multiplayer development, I needed to slow down the work on the Rating System, but likely this re-work on some of the code that we use as a foundation will help the Rating System, too, to proceed even smoother.

As a bottom line: enjoy the new content, both the car and track (in my opinion) are fabulous, and see how ACC keeps developing in the future.

I'm writing this between Multiplayer tests (on the new code), we are on a very good way – but sadly we will not see this outside the test systems for the time being.


While the rewrite is a project that remains ongoing, Kunos are still working hard at the latest build of the software, and that can be further evidenced today by a very small new hotfix update for the recently released Emil Frey Jaguar G3, the car having come with a couple of issues (mainly around the audio), which has been addressed as part of the latest hotfix build, details below:

0.5.1 Changelog
  • Improved intake sound EQ (onboard view) for the Emil Frey Jaguar G3
  • Minor LOD tweaks on the Emil Frey Jaguar G3

Busy days, weeks and months are ahead at Kunos HQ!

Assetto Corsa Competizione is available on Steam Early Access now. Currently at build release 5 status.

To keep abreast of all the latest news and discussions from the world of Assetto Corsa Competizione then don't forget to check out our very own ACC sub forum here at RaceDepartment.

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I must say, given the attitude over at Kunos, they know everything, they are the greatest, (one of them even has the audacity to call himself lord kunos), the frequent and immediate banning from their site anyone who does not agree 100%, perhaps this is what they needed. To be brought down to earth and swallow a bitter pill that they themselves have shoved down our throats. They would like us to believe that they can do no wrong and why would anyone as stupid as us question them. Yet, here we are. A huge mistake, or perhaps many mistakes and all the while after taking our money already. This should not have been released. It should have been worked on and resolved before even being in EA. I'm not trying to bash them, but just remind them and others of their attitude and treatment of many of us. I hope the game and Kunos survive this if only to have learned an important lesson. Kunos: Stop pretending you know everything and that you are above everyone else. Cleary we now see you are not.
 
The biggest rewrite should be optimising is the AI physics / code. Firstly they are terrible and secondly have such a hit on FPS it's pointless even having them.
It's not the AI and physics, it's rendering all the other cars. Very easy to demonstrate this conclusively by setting visible opponents to '1'.

All the AI and physics is still happening, but performance isn't much worse than hotlap.
 
You do know that AC and ACC are one of the very very few sims that run the AI on the same physics the real drivers are? pcars, rfactor use simplified physics for AI and basically "match" their performance to the correct laptimes but they are just not bound to the same physical laws you, as a real driver, are.
That's why each AI car hits the CPU performance so heavily.
Do I prefer 60 AI cars I can properly race with, that might use a different physics system than me over 10 AIs that follow the same physical laws I have to but are still not better to race with?
Complete misconception. See post above.

By my reckoning 60+ fields of AI cars should be realistically possible. ACC would just die trying to render them.
 
Complete misconception. See post above.

By my reckoning 60+ fields of AI cars should be realistically possible. ACC would just die trying to render them.
I'll benchmark full grid at low resolution vs 10 and report back! Maybe I remember something incorrectly but I do seem to recall that I had quite some gpu overhead left when fps dropped with a full grid!
Or do you mean that the drawcalls with visible AI hits the cpu more than the physics+AI calculation?
 
I dunno if it's specifically draw calls, but something to do with cars being visible just kills performance. The worst aspect of it is that there's barely any improvement when the 'visible' cars aren't even on-screen.

Try giving the AI half a lap start so they disappear from view entirely. You'd expect performance to improve to something similar to when visible opponents=1, but it doesn't get much better than being in the middle of the pack.

I can only speculate on what the cause is, but it feels like ACC is calculating visibility/LODs or something for each part of every car model independently, which would obviously be very intensive. You'd expect it to do something more along the lines of 'is this car visible?=no' which seems more efficient.

I'm no programmer, but find it hard to believe there aren't improvements possible in this respect. Everyone (myself included) always assumed AC struggled with AI and physics but didn't have the graphics option to demonstrate that it might not have been the case. I'd have expected this would be something taken care of by Unreal, so it seems weird that it might be the same thing.
 
I dunno if it's specifically draw calls, but something to do with cars being visible just kills performance. The worst aspect of it is that there's barely any improvement when the 'visible' cars aren't even on-screen.

Try giving the AI half a lap start so they disappear from view entirely. You'd expect performance to improve to something similar to when visible opponents=1, but it doesn't get much better than being in the middle of the pack.

I can only speculate on what the cause is, but it feels like ACC is calculating visibility/LODs or something for each part of every car model independently, which would obviously be very intensive. You'd expect it to do something more along the lines of 'is this car visible?=no' which seems more efficient.

I'm no programmer, but find it hard to believe there aren't improvements possible in this respect. Everyone (myself included) always assumed AC struggled with AI and physics but didn't have the graphics option to demonstrate that it might not have been the case. I'd have expected this would be something taken care of by Unreal, so it seems weird that it might be the same thing.
AI out of sight = full FPS in my case
 
Seriously (really "seriously"), how many of you are able to say how a GT3 car handling is?
Or a race car is?
My question is not for questioning, but giving the proper consideration to some judgements.

Well if you’re in or near the UK you could do just that...
https://driftlimits.co.uk/experience/mclaren/

I wouldn’t get too excited if you’re a regular track day or competitive driver it’s one of those nannied experiences with an instructor hawking over every action.

If you’ve got the money (I’m talking ££££ numbers) and some basic track experience it’s possible to drive pretty much anything. A race licence might be needed for some days - it’s easy and fun enough to get one. There are a few race teams who’ll take your money for a go at a test or track day.

If that’s too much effort or money for less than £1k the Porsche Driving School do some great days out in GT road cars that’ll get you pretty close - and they do encourage you to push the limits.

In my experience all the track cars I’ve driven are easy enough to drive within my enthusiastic amateur limits. The full works Impreza WRC rally car was a totally different experience, so much power, so little grip on gravel but that’s another story.

These sim games like AC, ACC and PCARS2 are getting damn close to the real experience especially in VR. That’s my opinion but it’s also shared by Dickie Meaden at Evo magazine and he’s also driven all sorts of race cars, hill climb cars, rally cars etc. I quote him because he’s probably closer to most of us in experience than full on race drivers and as a journalist he’s probably slightly more impartial than some of the on the books race drivers,
 
According to drivers that raced real GT3 cars, these things are super planted, what we simracers would call sim-cade.

These days in official level there are lots of overly positive acting. No one there wants to make a negative PR for anyone by just simply sharing a thought which has slight shade of negativity and hurt themselves too. There are so many talking heads. It creates overly positive delusional perception which is harmful for everyone.

Of course they probably truly are super planted, but it doesn't necessary mean that it is not required an effort to keep it like that as a driver. As a spectator you don't perceive modern racing cars being driven over the limit so much, thats most likely because those cars are bitches over the limit and drivers are afraid of that and works hard.
 
  • Deleted member 197115

It's not the AI and physics, it's rendering all the other cars. Very easy to demonstrate this conclusively by setting visible opponents to '1'.

All the AI and physics is still happening, but performance isn't much worse than hotlap.
Very true, AC rendering stats app demonstrates this very well. Main-T, which is rendering thread gets tanked first in VR, while PHYS is somewhere around 25-30%. Draw calls for multiple in motion opponents cars are more computationally expensive than physics calculation and it's single threaded.
 
I dunno if it's specifically draw calls, but something to do with cars being visible just kills performance. The worst aspect of it is that there's barely any improvement when the 'visible' cars aren't even on-screen.

Try giving the AI half a lap start so they disappear from view entirely. You'd expect performance to improve to something similar to when visible opponents=1, but it doesn't get much better than being in the middle of the pack.

I can only speculate on what the cause is, but it feels like ACC is calculating visibility/LODs or something for each part of every car model independently, which would obviously be very intensive. You'd expect it to do something more along the lines of 'is this car visible?=no' which seems more efficient.

I'm no programmer, but find it hard to believe there aren't improvements possible in this respect. Everyone (myself included) always assumed AC struggled with AI and physics but didn't have the graphics option to demonstrate that it might not have been the case. I'd have expected this would be something taken care of by Unreal, so it seems weird that it might be the same thing.
This is one of the moments where I have to admit that I was wrong. Entirely wrong!
Thanks for pointing this out to me as it means I'll be able to run full grids with limited visible vehicles in the future :)
Here's my findings:
While more visible cars definitely increase the GPU load, it increases the CPU load a lot more.
So even at 3440x1440, with my settings, I'm always CPU limited. My first test was at 1024x768 though.
Here's the fps numbers at race start, last position, zolder in the sunshine at 19:00, full grid:
~ 72 fps with all cars visible
~ 102 fps with only 1 car visible

At full resolution the numbers are the same. With only 1 car visible the GPU load drops enough to reach ~102 fps at 90% load and with all cars visible the GPU load stays at 90% but the CPU throttles the fps to ~72.

Very interesting and yes, I do think there is room for optimizations! :cautious:

And also thanks to Andrew! It perfectly explains why my AC1 performance is pretty similar online or with AI with around 16 cars on the grid.
I'd love to have the knowledge to know why some cars hit the CPU so heavily instead of just the GPU.
 
Well I was one who was amazed and excited about a UE4 developed racing game.
Over time, however, I'm finding this to be, simply put, a stick in everyone's side.

I'm glad they are up front about fundemental issues and the need to go back and re-do.
Great honesty.

However, for most of it, I have heard of multiplayer code.
At this point, I don't even think multiplayer is a good subject for re-coding. I'm not saying I'm right, it's just where things are now, I feel like multiplayer is but an afterthought to the integral issues within.

There are many basic sim racing things that "make or break" the experience....and game itself, really.

I haven't been able to really gauge how I feel about the underbelly of the simulation, because no matter what I do, I just can't get the FPS up enough to enjoy.

Triple Screen support
MAJOR performance improvements
Major UI elements and changes
FFB improvement/freedom (tough one, as FPS is a major factor, and "canned" forces are also a factor, like in AC)

I think these 4 things are sticking out as ACC's worst qualities right now, and with these 4 things still in limbo, it doesn't bode well in the future, for any compassionate sim-racer, or the developer.
It needs to be addressed. Openly and seriously.

I want the best for KUNOS because they pulled me in with AC and I still haven't left, really.
I still have confidence that KUNOS will remain realistic and honest, while also wizards of wild coding and amazing feats.

Edit: AI is another part of this, however I feel this comes 2nd to performance, as well as works in conjunction with such.
Also, one thing I have a bone to pick with in general with UE4 is.....I remember these amazing graphics demo's even as far back as 2012 and earlier! I find it hard to believe that this software can't be optimized (not ACC, just the engine) over this amount of time. The fact that many games are still coming out from UE4 with massive performance issues is leaving a pretty sour taste in my mouth about the engine, now. Not saying that it can't be done, or hasn't been done but....There's progress.....and then there's things that just work.
ACC is very stuck in the former. I hope there's an answer to this long-running issue.
 
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And also thanks to Andrew! It perfectly explains why my AC1 performance is pretty similar online or with AI with around 16 cars on the grid.
I'd love to have the knowledge to know why some cars hit the CPU so heavily instead of just the GPU.

AC1 is a strange beast - if I run it 7680x1440 on a single GPU I'll get something like 27% Main-T - however if I add a 2nd GPU that'll go up to 95% ( and apparently has pushed something on my aging motherboard over it's comfortable limits ). I haven't done any graphics work in far too long now, but there are still things in the pipeline which can get the CPU involved, swapping textures into VRAM is one iirc - shouldn't ever be a problem with AC and modern cards, but I wonder about ACC.
 
AI out of sight = full FPS in my case
I'd love to see some screenshots to demonstrate this, if you wouldn't mind?

1. Hotlap
2. Full grid, all cars visible and nearby
3. Full grid, all cars out of shot
4. Full grid, opponent visibility=1

In my experience 1 and 4 are fairly similar, as are 2 and 3. What you'd expect from 'optimised' graphics performance would be 1, 3 and 4 to be similar, and significantly lower FPS with 2.
 
After having spent a lot of online racing through different titles and car classes the past few years (PCars2, AC, iRacing), I come to the bitter conclusion for me that GT3 car class is just not a good class for Sim Racing; too slow, too good aerodynamics in relation to the power output, boring handling.
I wished they had introduced at least one other class in the performance segment of +/- Formula 3.
I think Kunos shows real dedication to their work, probably more than any other Sim developer company. Had a longer talk with Marco at the Sim Expo last year. You could feel the committment they have for the genre, so I am sure the title will be class A. Just with the wrong cars ;-).
 
no competitive structure, no working netcode, no racing details
They know they do not reach the stipulated date, they have a lot to correct, a lot. The fanboys will support them but the rest we know how bad the company is
compatibility with hardware, with peripherals, fix vr, try to incorporate triple screen the innumerable bugs that arise with each addition, etc, etc
ACC it pure disapointment about FFB
You said it, past, do you understand it fanboy? It is very clear that it is not going to be a good product

This is pure POISON. This is the ugliest face of internet forum and freedom of speech.
Please people, DON'T DO WHAT YOU DOING. You have nothing to win only to lose.
In the near future because of people like you the internet censorship will rise and we all we got lost our freedom of speech. BECAUSE OF YOU. This is not a joke, please think and reconsider what you doing online. Be civilized and polite. Please !!!!!!!!!!!!!!! Don't ruin this !!!!!!!!!!
 
This is pure POISON. This is the ugliest face of internet forum and freedom of speech.
Please people, DON'T DO WHAT YOU DOING. You have nothing to win only to lose.
In the near future because of people like you the internet censorship will rise and we all we got lost our freedom of speech. BECAUSE OF YOU. This is not a joke, please think and reconsider what you doing online. Be civilized and polite. Please !!!!!!!!!!!!!!! Don't ruin this !!!!!!!!!!

What?
 
This is pure POISON. This is the ugliest face of internet forum and freedom of speech.
Please people, DON'T DO WHAT YOU DOING. You have nothing to win only to lose.
In the near future because of people like you the internet censorship will rise and we all we got lost our freedom of speech. BECAUSE OF YOU. This is not a joke, please think and reconsider what you doing online. Be civilized and polite. Please !!!!!!!!!!!!!!! Don't ruin this !!!!!!!!!!
:confused:
 
@kunos Thank you for your commitment and for your transparency.
I really enjoy AC and I expect ACC to bee on par with it. Until now you are doing a good job. Of course some things are good, another not, but in the end all obstacles will be overcome and we all will enjoy a new better sim. Maybe not better then the rest of all sim, but a GOOD one (there is not the most better sim, every sim have his own personality, like we human beings have, because they are made by ... humans being who made mistake and are able to correct them or maybe not, but still human beings like me and you who read this forums and play those games)
It is nice to be part of your EA program and to see how this new sim grow up.
 
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