Physics The Physics discussion thread

[RC45]

Your ability to make fantasies from random assumptions is just mindblowing.

No - the suggestion was made that perhaps Kunos do not have accurate data - I didn't make that statement, YOU DID - this is you not me "And as you don't know if they use real geometries and stuff, your whole discussion becomes useless."

Nice try at changing the narrative..

You haven't been attacked for such thing

Yes, yes I was - attacked multiple times for trying to take tire data from an existing car without first changing it all.

Again, don't try change the narrative.

(plus you initially mentioned that that the tyres were different), you have been for making claims like

Again, you assume the only things I did where the things I posted about. You don't think I have not take the tires as-is as well to test?

God forbid I paraphrase or abbreviate a response - here to clarify then : Using part tweaked AND original tire files, the only way to achieve acceptable results was by manually tweaking and tunign the tire files until the car "felt right"
In Other Words - AC is based on feel not fact

There - happy?

"Although to be honest, as I have been working with real chassis data I have noticed that the AC physics engine is very very very far from being a real representation of real world physics using real world chassis data."

"Reporting these real world physics behaviors to Kunos will do nothing, there is no way Kunos will admit their toy engine is fundamentally flawed in a way they already know it is - the game may behave like a car simulator responding to real world physics data, but it is not."

"That is NOT how a simulation engine is supposed to work."

"It turns out that AC is a cute game for creating an ILLUSION of a REAL car, but the DATA used for that ILLUSION is not the real data but rather a massaged and manipulated version of the data."

And I stopped there in the first page already, if I add also all the nonsense about suggesting that AC should have realtime CFD and so on... Now don't pretend you are the victim after making such claims and ignoring the reasons/ideas etc given by other people.

No again - I NEVER suggested AC should have real time CFD, that was an absurd interjection by one of the cheerleaders.

What I suggested was that AC should be able to handle the wing attributes as blocks of separate input data - allowing the data to be moved between cars.

The same way YOU now claim that AC allows complete blocks of tire data be able to be moved between cars - again something that when I suggested was met with direct attacks.

Again repeating the same and lying... look, the truth here is that your car was almost fine with those tyres; you claimed the feeling was there just raising the camber, which means that you just needed to tune up a bit the lateral grip (a pretty good starting point considering that you don't have specific tire data, meaning that whatever you put in the tyre physics will be estimations), however your decision was to make all this shitstorm, going from accusations of physics engine being broken, to Kunos tuning the tyres by feel, and now accusing people of saying things that they didn't. I seriously don't understand what are you trying to achieve.

No - the truth is that I publicly discussed some things that AC cheerleaders hate to hear and was soundly attacked for doing so.

I have moved on already - I simply fudged the cars till they felt right. That's what AC modding is all about right? After all, NOW everyone keeps telling me AC is not a simulator what did I expect?

BTW, If AC was such a great engine, then it should be able to handle moving blocks of WING data between cars just as easily as it handles blocks of TIRE data being moved between cars.

 

[RC45]

No, because you are spewing nonsense....such as:


Because that is all rotational inertia actually is...one value... The inertia of each part is additive, so the physical properties of real life and AC ultimately leave you with a singular value. That's how physics work. You're showing a complete lack of knowledge of them.

First off, quit the insults. It is against the ToS.

Second, while being computed they are one value, but when collecting the data and to allow for more accurate and simpler modding, the total inertia should be able to be accounted for as the separate values they are.

If AC was as good as claimed then you as a modder, should be able to by data file editing, account for the DIFFERENCES that various mods would bring.

A stock GM rotor is all iron, and is heavier than an after market alloy hat rotor which is different again than a carbon rotor.

So rather than a SINGLE value that needs to be manually calculate for each type of modification the value for the ROTOR (along with the wheel, tire, hub) should be a separate value in the INI file for editing.

That is what I meant and it was CLEAR that is what was meant - YOU are now just being OBTUSE!

Because the value is buried in a total inertia value, it appears not to be possible to create "on the fly" setups using AC.

Something that even rF1 could do by the way. You line up the pre-edited setups using different wings, brakes, tires and wheels.

And then you make ridiculous assumptions such as this one...Jumping from the existence of a 2d texture to the conclusion that because of it, they must have gotten Hankook tire data, is absurd.

Again, lets leave the ToS violating personal attacks aside

It is a very reasonable assumption to make that because Kunos is a COMMERCIAL for PROFIT entity that UNLESS they have a BLANKET license with GM to ALSO cover the Goodyear or Michelin TIRES on the car being modeled - they (Kunos) may have a BLANKET agreement with say HANKOOK to use THEIR tires in game for all the unlicensed tires

You see, this is how things work in real life - so before you go attacking me you might consider that I do actually know what I am talking about - because I do.

The majority of your arguments are simply uninformed and nonsensical. And no that's not a "personal attack", it's objectively stating an obvious truth.

No, it is an attack, because as I have shown above you are in fact incorrect.

 

[mclarenf1papa]

Second, while being computed they are one value, but when collecting the data and to allow for more accurate and simpler modding, the total inertia should be able to be accounted for as the separate values they are.

If AC was as good as claimed then you as a modder, should be able to by data file editing, account for the DIFFERENCES that various mods would bring.

A stock GM rotor is all iron, and is heavier than an after market alloy hat rotor which is different again than a carbon rotor.

So rather than a SINGLE value that needs to be manually calculate for each type of modification the value for the ROTOR (along with the wheel, tire, hub) should be a separate value in the INI file for editing.

That is what I meant and it was CLEAR that is what was meant - YOU are now just being OBTUSE!

Hmm, that may be what you meant to say, but it's certainly not what you said.

"A single value to represent all the above?
Seems like a huge compromise right there.
Why not make allowances for unique values for each?
Oh thats right, just tweak till it feels right."

It's not a compromise to enter 1 value that performs the same function as 5 others...nor is it any less accurate...nor do you need to "tweak it till it feels right"....

Again, lets leave the ToS violating personal attacks aside

It is a very reasonable assumption to make that because Kunos is a COMMERCIAL for PROFIT entity that UNLESS they have a BLANKET license with GM to ALSO cover the Goodyear or Michelin TIRES on the car being modeled - they (Kunos) may have a BLANKET agreement with say HANKOOK to use THEIR tires in game for all the unlicensed tires

You see, this is how things work in real life - so before you go attacking me you might consider that I do actually know what I am talking about - because I do.

Calling your statements ridiculous is not a personal attack...calling you ridiculous would be a personal attack; there's quite a big difference between the two.

"they (Kunos) may have a BLANKET agreement with say HANKOOK to use THEIR tires in game for all the unlicensed tires"
Yeah but that's the thing, you're assuming that they have an agreement with any tire manufacturer to use data from one of their tires in game....because they have a texture with a Hankook logo on it....

 

[Mr.Mugel]

It makes sense to add all values of the unsprung masses (as was the example here) into one, so you only need to calculate it once, instead of the CPU calculating it 333 times per second for a maximum of 32 cars, 5 additions, so we just spared about 53.000 calculations per second. That is why it absolutely makes sense to condense some things in the model.

Edit: And just to add it, even manufacturer CFD/FEM calculations, etc., which can have calculation times as long as weeks for ONE single state need some fudging factors, as you can´t allways simulate everything. Got to agree with Stefano here, if you wouldn´t want fudging factors, you´d need to simulate at submolecular level, which is just not possible.

Simulation is allways a compromise to recreate physical behavior on basis of a limited number of input variables and also based on our still limited physical understanding of some processes. Additionally you need to do it all in way way less than a blink of an eye with severely limited processing power if you want to do real time simulation.

 

[Michael Hornbuckle]

A couple of interesting posts from the official forums:
Stefano:
If you are talking about the suspension system for example then yes, measuring the real car suspension will result in a simulation that is pretty close to reality. If you are talking about tyres then no, measuring a tyre won't tell you anything about the behavior of the tyre itself. Same with aero, measuring a wing size, or the bonnet size or a grill size won't tell you anything about the aerodynamic behavior of that car, you need to get a different set of data altogether.
---------------------------
This question was asked:
I have a question about Tires in Assetto Corsa. Let's use "Semislick" as the example. Does the Semislick tire have exactly the same parameters (besides size?) for whichever cars offer it? Like, is the Semislick on the Countach exactly the same as the Semislick on the F40? Or is "Semislick" a collection of base data values comprising 95% of the tire's characteristics and each car can/must be adjusted based on which automobile is using them? How are tire sizes handled? Rim size? Width of the tires?
Aris answered:
No, that would result in terrible handling.
Tyres in AC, start from the dimensions (i.e. 245/40/17), load index, compound (i.e street, semis, slicks etc) and era (year of construction). We have connected this basic starting points/dimensions to various equations that in the end create different values for every single of the tyres.ini strings. If we have done the equations right, we never touch the results, and we create a tyre almost "automatic".

The above approach give us two very important advantages.
- All different tyres are "connected" and "proportional" in some way. This means that whether you drive a car with 135/80/13 tyres, or 325/30/21, the "feel" and behaviour of the tyre is... comparable. It's like driving in reality a small car and then jumping to a supercar. Yes the differences are a ton, but the basic feel from the wheel, feel of connection to the road, feel of adhesion etc. is... similar.

- You might have noticed that in real life the car manufacturers choose very different tyre dimensions depending on the weight, power and performance of each car. This is not made for (or just) aesthetic reasons or randomly. The correct tyre dimension, load index and compound, is crucial for the handling balance of each car.
So when we have good enough data about suspension geometry, power, weight, aero, for completely different cars, say a front heavy FWD supermini, a neutral 50:50 BMW and a rear heavy Porsche, and we put our "automatically" created tyres and the cars handle instantly as they should, then this is a great indicator and a perfect reverse engineering index that confirm us that we are doing something good. If something is out of bounds, then we are wrong somewhere and we have to go back to the drawing board.

How we arrived on that "automatic" creation of tyres, how much time it took and what happens to it, to me and Kunos everytime we decide to do a new tyre model... well this is something I cannot tell you, otherwise we're going to lose the PEGI 3 rating...
--------------------------------------------------------------

When are we going to see a video of the definitive C5 mod that we can't have?

 

[David Dominguez]

It's just useless to keep discussing, nothing will change is mind.

 

[Michael Hornbuckle]

Forget him, there is good info in this thread for actual modders, hope the discussion continues.

 

[Giorgos Kostis]

I hope this whole thread gets deleted.

Why waste 9 pages of time for someone who trusts only himself?.

 

[Giorgos Kostis]

Btw if you look at assetto corsa 1.9 sound thread, you can see that he talked to kunos themselfs like he knew everything about physics.

 

[RC45]

You people still going on about this? Sorry I was not around to read your posts - I was off working on my real life 250cc GP bikes. That's the thing with real life, it is fascinating and diverse - you should try it out once in a while.

Calling your statements ridiculous is not a personal attack...calling you ridiculous would be a personal attack; there's quite a big difference between the two.

Again with the personal attack disguised as an explanation.

Post reported.

"they (Kunos) may have a BLANKET agreement with say HANKOOK to use THEIR tires in game for all the unlicensed tires"
Yeah but that's the thing, you're assuming that they have an agreement with any tire manufacturer to use data from one of their tires in game....because they have a texture with a Hankook logo on it....

It appears you are now suggesting that Kunos is using tire textures from real manufacturers without any agreement? Not even an agreement to use the likeness of their product (sans data) and that they have made up all their tire data.

Please - pick a side - either Kunos has accurate tires modeled with proper data or they do not.

Which is it?

 

[RC45]

It makes sense to add all values of the unsprung masses (as was the example here) into one, so you only need to calculate it once, instead of the CPU calculating it 333 times per second for a maximum of 32 cars, 5 additions, so we just spared about 53.000 calculations per second. That is why it absolutely makes sense to condense some things in the model.

I dare say you are not correct int he above assessment - any half competent weekend hack programmer could simply total up the values for the individual line items when the car was loaded into memory and use the total. No extra calcs needed at run time.

The real value of having the separate inertia contributing items in the ini file would be so you could have a game that allows the USER/PLAYER to modify the car from a pick list of available options rather than REQUIRE a complete new car be created just because this car might use a lighter or heavier brake rotor.

In a game that was trying to simulate a car that is often and easily modified in real life, the USER should have the option of picking the brake setup and then the GAME engine should compensate for the run time changes to the unsprung inertia value change.

rFactor1 could do it - surely the newer better awesomer PERFECT AC should be able to handle this little option?

 

[mclarenf1papa]

You people still going on about this? Sorry I was not around to read your posts - I was off working on my real life 250cc GP bikes. That's the thing with real life, it is fascinating and diverse - you should try it out once in a while.


Again with the personal attack disguised as an explanation.

Post reported.


It appears you are now suggesting that Kunos is using tire textures from real manufacturers without any agreement? Not even an agreement to use the likeness of their product (sans data) and that they have made up all their tire data.

Please - pick a side - either Kunos has accurate tires modeled with proper data or they do not.

Which is it?

Again with the reading comprehension....

No that was not a personal attack (report it all you want), no I'm not suggesting Kunos is using logos without an agreement (not at all what I said), and no I'm not swaying between arguments...I "picked" mine ages ago. Kunos tires are generated by mathematical formulas that aim to replicate real data, but will never match it perfectly (David and I have said this time and time again but you refuse to actually understand that fact). That's my "side" and has been since the inception of this thread, end of discussion.

 

[Ben O'Bro]

jeez, let's move on. This thread is making me sad.

 

[Radu Oros]

jeez, let's move on. This thread is making me sad.

Exactly, since he refuses to make his mod and release it, is already a "work in progress" since 2009 from rfactor.. I wonder what was the excuse given back then, game graphics not worthy of his mod?

 

[RC45]

Again with the reading comprehension....

No that was not a personal attack (report it all you want), no I'm not suggesting Kunos is using logos without an agreement (not at all what I said),

So they do have an IP agreement with a tire manufacturer then? Or are you again suggestign they are using an image and likelness without permission?

and no I'm not swaying between arguments...I "picked" mine ages ago. Kunos tires are generated by mathematical formulas that aim to replicate real data, but will never match it perfectly (David and I have said this time and time again but you refuse to actually understand that fact). That's my "side" and has been since the inception of this thread, end of discussion.

I have from the get go said Kunos is guessing and fudging to get the feel they want out of tires and I get attacked for just suggesting this.

So we have now ascertained by way of your own comment that not only are the tires fudged per car, but the fudge factor is not even based on real data but rather generated "close enough" data.

This was the gist of my opening post - so we are in agreement.

 

[RC45]

Exactly, since he refuses to make his mod and release it, is already a "work in progress" since 2009 from rfactor.. I wonder what was the excuse given back then, game graphics not worthy of his mod?

Actually I have been enjoying the rFactor version for years now. My car is modeled along with a number of other friends cars. But the port to AC required a step backwards in accuracy to get the cars to "feel" the same

Here is a video from 2009

And another show casing the Katech C6 Clubsport

And another from 2011.

 

[mclarenf1papa]

So they do have an IP agreement with a tire manufacturer then? Or are you again suggestign they are using an image and likelness without permission?


I have from the get go said Kunos is guessing and fudging to get the feel they want out of tires and I get attacked for just suggesting this.

So we have now ascertained by way of your own comment that not only are the tires fudged per car, but the fudge factor is not even based on real data but rather generated "close enough" data.

This was the gist of my opening post - so we are in agreement.

Honestly I'm sorry, but I'm not going to continue if you're going to misinterpret absolutely everything I write... To hopefully conclude my time here, I'll simply say that no, we are not at all in agreement.

 

[Mr.Mugel]

I dare say you are not correct int he above assessment - any half competent weekend hack programmer could simply total up the values for the individual line items when the car was loaded into memory and use the total. No extra calcs needed at run time.

The real value of having the separate inertia contributing items in the ini file would be so you could have a game that allows the USER/PLAYER to modify the car from a pick list of available options rather than REQUIRE a complete new car be created just because this car might use a lighter or heavier brake rotor.

In a game that was trying to simulate a car that is often and easily modified in real life, the USER should have the option of picking the brake setup and then the GAME engine should compensate for the run time changes to the unsprung inertia value change.

rFactor1 could do it - surely the newer better awesomer PERFECT AC should be able to handle this little option?

Yeah, possibly, but still, why? The game does not feature car modifications except for those given in the setup, it doesn´t advertise that and it probably doesn´t have the license to include it for many cars.

 

[RC45]

Yeah, possibly, but still, why? The game does not feature car modifications except for those given in the setup, it doesn´t advertise that and it probably doesn´t have the license to include it for many cars.

From that should we then conclude that AC is just another so-so PC car game, and not much of a simulator at all? - which is one of Kunos' advertised claims - I think it is right there in the name

 

[J-Lius]

From that should we then conclude that AC is just another so-so PC car game, and not much of a simulator at all? - which is one of Kunos' advertised claims - I think it is right there in the name

Isn't car upgrade system exactly a thing that is found in more "arcadey" games but not in any modern sim?