Our ReVolt Pub

Is there any way to calculate the friction values?
What do Kinetic and Static Friction entries represent in the Parameters file? Coefficient of friction or frictional force or are they simply empirical?

I dunno why you would want to "calculate" those. I don't think you can anyway.

Static friction is how much grip the car has normally when it's going straight or standing still and Kinetic friction is how much it has when it is turning/skidding. Higher values give it more grip and makes it more difficult to spin, lower values is the opposite. Kinetic friction is NEVER higher than the Static (unless you're just seriously messing around for whatever reason.) You can differentiate the two frictions, most cars are more fun to drive when you can slide them around corners slightly.

All you can really do with them is just play around until the car behaves how you want it to.

Erm..well i know the stuff you posted. So do you mean these values are completely empirical?

To tell you the truth...and I know City will disagree with me because I know she likes her math, lol...but for me, every single number in that file is empirical. Absolutely everything I do is on a 'relativity' basis. <smiles>

I take each parameter and experiment with it to find out what -the game- does with it. I know physics...or at least I should say I know how most things should move and how they should -feel- when they do it...what I'm still in the process of doing is determining how the game of Re-Volt translates all that information. And I'm getting a lot better at it the more I do it.

Once you have that...you have a 'scale' for each parameter in your head...and it's all relative. I know that if a car has 'this much' weight, then 'this much' of that or the other thing with have 'this much'' effect on it. Hmm...you could perhaps think of it as one of those control panels that sound engineers use that you have seen outside of recording booths when they are laying down tracks for a song. Each slider on that board represents one of the settings in the parameter file...and I know what effect (in relative terms) each end of that 'scale' will have on the car.

So my slider/scale for EngineRatio for example, goes from zero...or no power supplied to the wheel...to what is currently 256500.000000...which is the value used on my Amanra XT Stunt Version. So...as a result of experimentation...I now know what effect the EngineRatio will have on the car if I set it anywhere from zero to that ridiculously high number I just posted above.

I kept doing this...adding sliders and determining a relative point of reference for each setting. Yes, this took a little time. But...

Now...I can just walk up to my 'control board'...or a set of parameters...and just 'adjust my sliders'...or the various individual values...to very quickly establish the basic character of pretty much any kind of vehicle I want. I then put the car through it's paces on the track and adjust things based on the behavior that I observe. Works great.

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But here's the thing...
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This all works great FOR ME. It is how I conduct my own personal symphony of motion. You, on the other hand...might be completely different. Find out how -you- learn best...how -you- like to think about things...and then make -that- work for you.

Mythic

I don't even know what 'empirical' even means...

"Empirical" means "found by trial and error".

@Mythic:- To be honest, i too would have loved a mathematical relation to calculate the values. But if everything is relative, i would try experimenting.

Haha...yeah, I know, Pranav. <smiles> I could tell simply by your first question that you are a bit more comfortable having some kind of set structure to work with. I have that...I just made it myself. <smiles> The fact is, there -might- be some way to calculate all this stuff. I would not be the least bit surprised if there was.

However...

In my mind, this would require some things we currently don't have.

1) An intimate knowledge of exactly how the Re-Volt physics engine works so that you have a 'translatable' point of reference. Basically you would need to know that a KineticFriction value of 1.95 equates to a quantifiable amount of grip on real-world tires, for example. Each value in the parameter file would need to have some kind of equivalent real-world value.

2) Next you would need to know what all those actual real-world values were and be able to quantify them in a way that Re-Volt could use. <smiles> So who can tell me how much kinetic and static friction a set of Yokohama tires has? How about the amount of low-end torque on a Nissan Skyline GTR? Hands?...anyone? Hmmm...me neither.

Perhaps you can see the problem.

So I work with the information that -is- available to me...my own personal experience with such things, and a whopping lot of just plain figuring things out. So yeah, there might be some way to calculate all these values, but in my opinion we are missing some pretty important factors in that particular equation.

For the game of Gran Turismo, they did that...they came up with a system to quantify all these variables. They also built into the structure of the game itself a way to translate all these values because for that game, they -were- looking to create a realistic simulation and they set everything up to support that premise. Re-Volt however, did not do this, or even anything close to it. So this leaves us...as far as I can tell...in a place where we just have to figure things out by eye and feel.

Mythic