New Assetto Corsa Competizione Physics Blog Post

[Paul Jeffrey]

Aristotelis Vasilakos of Kunos Simulazioni has started a new blog post series, digging deeper into the physics of the upcoming Assetto Corsa Comeptizione…

As the initial 'Early Access' release of Assetto Corsa Competizione begins in just one week's time, the team over at Kunos Simulazioni continue to be hard at work behind the scenes making adjustments and improvements to this hotly anticipated new simulation.

Already we have learnt much about the content and direction of ACC, however one of the things that are perhaps most anticipated by the community must be the physics of ACC, and how they will compare in a brand new game engine alongside the highly regarded original title.

To help shed some light on the subject, and build up the hype, ACC physics guru @Aristotelis has shared a brilliant new blog posting, the first of a proposed series of posts on the inside workings of the physics for ACC.

You can check out the full blog posting from Aris below:

Hello everybody!

The Assetto Corsa Competizione Early Access is about to begin and once again we’re ready to start a fantastic journey.

First things first, Early Access means that you get the opportunity to get early versions of the final game and have a look on the development and evolution of ACC. Obviously, once you bought the EA version, you get all the following updates of the main game for free. On the other hand we, developers, get the opportunity to collect feedback and impressions while we work, from a much bigger testing team the we could ever organize in private.

Our responsibility will be to try and update the title on the pre-announced dates, offering great new content and as stable features as possible, so that you guys can enjoy the game and keep the feedback coming.

Obviously, that means that the initial versions of the game will have limited content and features, but we are confident that we can offer the same successful evolution experience as we did with AC Early Access period.

I hope that the above is clear for everybody and the community can spread the word and inform other simracers that might not know what Early Access means.

While many of ACC gameplay features won’t be available in the first releases of Early Access, the driving physics simulation is mostly ready. Some fine tuning and some extra features are still needed, but… there’s plenty to talk about so let’s talk… physics!

So what physics ACC runs? The first test Stefano did when we started exploring the Unreal Engine, was create a version of our AC physics and make it run inside UE. I won’t go into details, I won’t even know how to explain it, but after lot’s of cursing, insomnia and head scratching, he made it. So the first initial versions of ACC had the AC physics running.

Next step and part my main job for the time, was to try and do as many parallel runs between AC and ACC:UE to make sure the physics was absolutely identical, trying to eliminate any possible placebo effects, doing laptimes comparisons and handling comparisons. Once we got absolutely sure that everything was identical, the fun part (or the nightmare part, depending on how you see it), began.

The initial idea about ACC physics, was to evolve and improve weak points of AC physics and then move on from there. Not sure if we skipped it completely or gradually moved from one plan to another… too many things have happened and to be honest, considering the end result, it doesn’t matter anymore. What it does matter is that ACC, although it might “feel” similar, it certainly is much more than that. Stefano will probably call it evolutionary, but to be honest there’s so much new stuff that I’m not sure that term makes justice.

So, heavily reworked tyre behaviour model, heavily reworked tyre heating model, heavily reworked tyre wear model all of them not just reworked values but with all new physics features, equations and data. On top of that we got reworked brake heating model… but more about all of this on a dedicated post about tyres and brakes.

Suspensions. We got completely new damper model. As you know dampers are usually simulated in sims with 4 values. Bump, rebound, fast bump and fast rebound. But… in ACC we know have full blown damper graphs. Obviously in the setup screen you guys have the usual clicks to work with, but under the surface, each click points to a different damper graph. Also, we have a completely new bumpstop system. The bumps have variable stiffness and variable ramp (graph) of their stiffness. That was actually a forced evolution of the physics, because otherwise it would be practically impossible to set properly the cars, because of the very advanced aerodynamic model… just as in real cars.

Which brings us to the aero model. Completely rewritten from scratch. This is not even an evolution, it’s a complete rewrite. Instead of creating various “wings” that each one of the generates a specific lift and drag around the car, as in AC and more or less all the simulators out there, ACC uses a new system that takes into account aeromaps from wind tunnels or CFD and applies lift and drag to the whole object as one. Doing so, it takes into account on how the object moves its aerodynamic pressure point forward or backwards depending on pitch and yaw. Before saying that this is something you can achieve with the “wings” model of AC, I can assure you it is different. The system actively moves the pressure point and can influence front or rear lift and drag, depending on what it happens in the car pitch rotation, wing angle and so on.

The end result, is a much more pitch sensitive aero platform with situations that force you to choose specific ride heights, wing angles and suspension settings to counteract the aero influence on the handling. Because of this, as in real life, maintaining the aero platform becomes crucial, ride heights are probably the most important part of the setup and bumpstops become extremely important to control the car.

The GT3 cars do heavy use of ABS and Traction Control systems, permitted by the rules. So for ACC we had to improve furthermore the ABS and TC systems. They have become quite more complex, taking into account much more information and telemetry inputs as well as having different behaviour and output result.

Obviously we also have a completely new weather system and dynamic track. The rain simulation is really a breakthrough and, modesty apart, I’m confident that you guys are going to be impressed by it. All hail Lord Kunos, he really did an astonishing work and of course I'll do my best to explain you all the various situations, simulation and techniques to get the best driving experience out of it.

TL;DR

So, I just wanted to give you a small taste of what I’m going to cover in more detail in the following days. I’ll try to write specific posts about tyres, suspensions, aerodynamics, TC and ABS, setup screen and strategy and weather simulation.

Once again, thank you for all the support you are giving us and we really hope you’re going to enjoy the initial early access releases. Looking forward to your feedback and to the more advanced releases in the next months, when ACC will really start to shine! ​

Using the undeniable talents of the team at Kunos, building on the lessons already well learnt from the original title, and with a nice and shiny new graphics engine to boot, ACC already looks to have the makings of a classic firmly wrapped up...

Assetto Corsa Competizione will be available to purchase on Steam Early Access from September 12th 2018.

Check out the Assetto Corsa Competizione here at RaceDepartment for the latest news and discussions regarding this exciting upcoming sim. We intend to host some quality League and Club Racing events as well as hosting some great community created mods (we hope!). Join in the discussion today.

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 Did you enjoy the new blog post from Aris? Looking forward to ACC? Do you think the game will improve on the original Assetto Corsa? Let us know in the comments section below!​

 

[Opus131]

My second point: Why do we care so much about realism if over 90% of us is never gonna drive a real race car? Why do we need to improve our skills on the most accurate simulation possible if we're only gonna use that to play with our toy wheels at our basement most of the time?

Because the realism is part of the entertainment.

I agree with much of what you said regarding why AC is more popular than rFactor 2, and those are things to consider if the argument is about whether there's a point in playing anything else beside rF2 or AMS. With that said, realism is the entire point of those type of games, and to a certain extend realism constitutes gameplay. There has been a trend to streamline games this past several years that seems to go hand in hand with an increase in the quality of the presentation. Many games nowadays seem to focus on what essentially amounts to fluff (increased immersion, visual "cues" of various kinds, non-interactive cinematic set pieces and so forth) at the expense of concrete gameplay elements that have been either simplified or reduced altogether. Even something as basic as the FPS genre has been dumped down. Level design isn't as complex as it used to be, gunplay is simpler, less skill intensive, and the competitive online scene has moved towards squad based games because of the lower skill ceiling.

This has been the case with almost every other genre, and one may argue racing sims are moving towards the same path. The problem isn't even realism or accuracy. The problem with some of those popular racing games is not so much that they are less realistic than an rFactor 2, but that some of them are veering towards the arcade rather than simulation category. The term "simarcade" has been coined to describe some of them, and arcade games is not what i signed up for. I want my game to be a simulation. I want to feel as if i'm the one in control and there's no invisible hand determining my interaction with the game. I'm not saying this is necessarily the case with AC, a game i had a great deal of enjoyment with, but just the suspicion of that bothers me. I loaded ACC for the first time today and the new UI alone gave me instant misgivings. Now the game itself seems promising but stuff like this always makes me queasy.

 

[Diogo Goetz Brand]

Because the realism is part of the entertainment.

I agree with much of what you said regarding why AC is more popular than rFactor 2, and those are things to consider if the argument is about whether there's a point in playing anything else beside rF2 or AMS. With that said, realism is the entire point of those type of games, and to a certain extend realism constitutes gameplay. There has been a trend to streamline games this past several years that seems to go hand in hand with an increase in the quality of the presentation. Many games nowadays seem to focus on what essentially amounts to fluff (increased immersion, visual "cues" of various kinds, non-interactive cinematic set pieces and so forth) at the expense of concrete gameplay elements that have been either simplified or reduced altogether. Even something as basic as the FPS genre has been dumped down. Level design isn't as complex as it used to be, gunplay is simpler, less skill intensive, and the competitive online scene has moved towards squad based games because of the lower skill ceiling.

This has been the case with almost every other genre, and one may argue racing sims are moving towards the same path. The problem isn't even realism or accuracy. The problem with some of those popular racing games is not so much that they are less realistic than an rFactor 2, but that some of them are veering towards the arcade rather than simulation category. The term "simarcade" has been coined to describe some of them, and arcade games is not what i signed up for. I want my game to be a simulation. I want to feel as if i'm the one in control and there's no invisible hand determining my interaction with the game. I'm not saying this is necessarily the case with AC, a game i had a great deal of enjoyment with, but just the suspicion of that bothers me. I loaded ACC for the first time today and the new UI alone gave me instant misgivings. Now the game itself seems promising but stuff like this always makes me queasy.

I agree for the most part, I'm not saying I don't care about realism, otherwise I'd still be playing Forza 4 on my Xbox 360. But while people always demand "rFactor 2 realism", they forget that rF2 gave up on many important aspects of the game to achieve that realism. What's the point of a complicated tyre and suspension model if there are no laserscanned circuits, and up until recently, almost no officially licensed cars? Laserscanned circuits and official cars also make up for the realism of the game.
Also, I don't see why the ACC UI being more flamboyant would mean the game trends towards less realism.
It's like a car setup, it's all about compromise.

 

[Opus131]

I'm not sure it necessarily follows that they had to give up anything to achieve those levels of realism, except graphics since those are time consuming and expensive to make, and are usually the first thing to be sacrificed when a game attempts to increase technical sophistication in other places.

Those things you mention could very well be the result of incompetence, and it is conceivably possible to have a game that is both realistic and not be as much of a mess as rFactor 2 was at launch.