Welcome Guest [Log In] [Register]
Welcome to Re-Volt Live. We hope you enjoy your visit.


You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are some features you can't use. If you join our community, you'll be able to access member-only sections, and use many member-only features such as customizing your profile, sending personal messages, and voting in polls. Registration is simple, fast, and completely free.


Join our community!


If you're already a member please log in to your account to access all of our features:

Username:   Password:
Add New Reply
Custom Cars With Real-life Handling; Tutorial of what to change and how
Topic Started: Jan 9 2011, 06:22 AM (3,217 Views)
Citywalker
Member Avatar
Resident Tinkerer
[ *  *  *  *  *  *  *  *  *  *  *  * ]
Edit:
I am officially humbled. It actually took me over 8 months(!) to realise that with the initial long and complex tutorial, the RL cars were handling like grandma’s station wagon on ice, instead of race cars.
I’m sorry.
And I’m grateful to Burner94, for his patience at testing the Inertias.
This is a re-written tutorial – simpler, correct, and cars remain playable for both you and the AI.

- - - - -

First of all – you don’t have to read all this text below.
Here are the quick instructions for the impatient (without all the “why”):
1) Divide EngineRate by 25.
2) Multiply the first Inertia value by 2.5 (3 fits Carmageddon cars, but not others) and the other Inertia values by 3.
Done! :)
(Optionally, you could also set ResMod to 1.0).



And now for the longer text, with reasons given for everything.

Why Real-Life (RL) handling at all? Because by now, the world of custom tracks is effectively divided into two – RC style tracks in homes and gardens, and RL style tracks in life-size cities and racing circuits. And the original RC handling seems very much out of place in a life-size city. SS Route Re-Volt is by now the best showcase of that. If you have doubts about the difference, try an RC and an RL car there, or show it to some other pessimist :)

Okay, some time ago I said in some topic that I'm able to give any Re-Volt car life-like handling. Well, I can already hear someone thinking “that's very ambitious of you to say”. Yes, it turned out that it really is an ambitious claim, because custom cars can be veeery different, and not all respond well to a generalised approach. But most of them don’t have any special quirks and can be transitioned to RL handling with a generalised approach or just minor tweaks.

<puts on glasses and assumes a lecturer's pose>

What you need:
• A car.
• This tutorial ( :) ).
• A calculator. (A spreadsheet is not really necessary anymore...)
• A decent AI. If it's good enough to race the car in RC form, then it'll usually be able to do so in RL form as well.
• A good life-size style track or two, to test the feel of the results. Currently the best track for visual feel of the new handling is SS Route Re-Volt. But it's not suitable for AI testing (seems to have lousy track nodes), so the RL testing kit should also include something from e.g. Hilaire, and my own test set currently includes Super Nova (motocross style jumps for air feel). Maybe something like Atlanta is good, too, for circuit racing type cars.

What has to be changed:
The point is to change the properties that make a car feel like RC, to feel like a life-size one. In Re-Volt, this comes to mainly three things:
1) RL cars accelerate slower than RC ones.
2) RL cars roll over and tumble slower than RC ones.
3) RL cars generally steer slower than RC ones.

How to do it:
The corresponding parameters in parameters.txt are these:
1) Acceleration -- EngineRate under “Handling related stuff”
2) Rolling and tumbling -- Inertia matrix under “Car body details”
3) Steering – Inertia matrix actually takes care of that as well.

1) Acceleration. Real-life car engines have much more car weight to push around, so they are relatively much weaker per weight than the powerful electric motors in featherweight RC cars. Play-testing (by UrbanRocker and Burner94) has shown that if you take the usual Acclaim EngineRate (which nobody really seems to modify in their customs :) ) and divide it by 25, you get acceleration that is slow enough to be on a real-life scale and still high enough to have responsive throttle in/after a curve. All in all, a relatively good sportster acceleration, depending on the RC car's acceleration properties of course.

Those of you who think that the best way to reduce acceleration is to reduce the EngineRatio parameter under “Car wheel details” may find it useful to know that I have stumbled along that path myself, and found out that this is not recommended, because it directly affects wheelpower and that's needed for climbing steeps. Better change the acceleration directly with EngineRate.

2) Rolling and tumbling. First of all, think and decide whether you want your cars to have the default flying-in-syrup effect of Acclaim or to tumble and roll realistically. That choice pertains to both RC and RL cars, IMO. Fortunately, this is an easy change: simply make the ResMod parameter 1.0 (1 as in scale 1:1 to real world physics). And if you are still undecided, then Jigebren's WolfR4 for the old V1207 game allows overriding the usual ResMod 25 in-game to have the ResMod 1.0 effect anyway.

Second: real-life cars usually contain a ton of metal or other material and this much mass has considerably more inertia than a kilogram of an RC car. This is why crashing RC cars roll like balls and crashing RL cars roll like, well, cars. Thus, the Inertia matrix of the would-be real-life cars has to be changed. After much time, I have finally realised that all you need to do is to multiply the Inertia values by 3. This is the maximum that the AI can still handle, and it still gives a good heavy feel to a car.

(There was a longish text here about calculating the inertia values with a formula. It’s of no use for RL transition anymore, but I’ll leave it here in a shortened form, because it’s a good way to get RC inertia for any weight so that it feels right in Re-Volt. See at the end of the post for this.)

3) Slower steering. The higher Inertia values take care of this automatically, because the second value controls the left-right spin speed of the car and thus makes turning heavier as well.

And that’s it. The AI can be left as-is, if it was good in RC form. Of course, if it was bad in RC, then it’ll be worse in RL, but for tweaking that you need to see the AI tutorial.


<starts to step off the lecturer's podium>
Oh, the Inertia formula for RC. Here it is, just so that it doesn’t disappear from the Internet.
For the mathematics buffs and otherwise interested people:
Re-Volt uses quaternions or somesuch for inertia calculations (ugh!), so the formula that I finally determined is somewhat empirical. But it works reasonably well.

The actual formula for calculating inertias is this:
• Inertia=ref_inertia*weight+(weight-1)*inertia_coeff*weight,
Where:
ref_inertia is 700 (the inertia at weight 1 kg),
inertia_coeff is 350 (an empirical coefficient to get the calculated inertias to spread out evenly according to car weight),
weight is the car’s weight in kg (the parameter Mass under the section “Car Body details”).

Calculate the first Inertia value with this formula (X_Inertia).
The second Inertia value (Y_Inertia) = X_Inertia multiplied by 1.5.
The third Inertia value (Z_Inertia) = X_Inertia divided by 2.

You can play around with the ratios (1.5 and 2) for an individual handling.
And you can play around with the ref_inertia (700) for different effects. For example, 2100 (i.e. 3 x 700) gives the RL inertias and 400 (almost halved) gives Hot Wheels like inertia.


<comes off the lecturer's podium>
That's all for now. If any new information crops up, I'll update this tutorial.

Have fun!
All my stuff is available here, and all my videos are available there.
-----
CW
Offline Profile Quote Top
 
URV
Member Avatar
Sir Pongus
[ *  *  *  *  *  *  *  *  *  *  *  * ]
I though Einstein died a long time ago.
re-volt.io | Online Races | Discord Server | My Creations
Offline Profile Quote Top
 
kay
Member Avatar
Re-Volt Chieftain
[ *  *  *  *  *  *  *  *  *  *  *  * ]
amazing indeed :)
hoping I get some free time soon to read this fully can't wait!
It wouldn't hurt visiting my blog or Re-Volt frontend's :)
Offline Profile Quote Top
 
Citywalker
Member Avatar
Resident Tinkerer
[ *  *  *  *  *  *  *  *  *  *  *  * ]
Edited again, because important facts were discovered. The final play-testing is still going on, as Urban seems to have little time for this, but it has worked well for my own Challenge Pack(3), so it should be okay. I’ll tell here when Urban confirms these changes.

+ EngineRate was lowered too much. Credits go to UrbanRocker for testing my theories into a much better EngineRate coefficient.
+ It turned out that all cars can be transitioned with KineticFriction and CoM height. No Grips editing is necessary.
+ The original understeering/oversteering behaviour is now properly and fully preserved, by editing the CoM height (important!).
+ (Was: Good RC AI can be easily transitioned to RL and it remains good.) Only if the car is easy. Re-Volt's AI coding is a bit broken, it seems.
+ Added notes about a special case, i.e. leaning bikes etc.
+ Added a note about a good RL testing track.
+ Added the “Why?” of RL style cars.
All my stuff is available here, and all my videos are available there.
-----
CW
Offline Profile Quote Top
 
URV
Member Avatar
Sir Pongus
[ *  *  *  *  *  *  *  *  *  *  *  * ]
CW
 
SS Route Re-Volt is by now the best showcase of that.


I disagree. In my honest opinion, RC Dream is the best.

Sorry, I have a busy week at the moment... It might have to wait for a while.
re-volt.io | Online Races | Discord Server | My Creations
Offline Profile Quote Top
 
Citywalker
Member Avatar
Resident Tinkerer
[ *  *  *  *  *  *  *  *  *  *  *  * ]
RC Dream has no replay cameras. Driving feel is one way to sense the difference, but another good way to spot it is the F5 TV-cam of a replay, when you don't have to concentrate on driving anymore, so you can just observe.
All my stuff is available here, and all my videos are available there.
-----
CW
Offline Profile Quote Top
 
Citywalker
Member Avatar
Resident Tinkerer
[ *  *  *  *  *  *  *  *  *  *  *  * ]
And another edit, this time to narrow down the CoM height transition, and to give new procedure and information about AI.
All my stuff is available here, and all my videos are available there.
-----
CW
Offline Profile Quote Top
 
Citywalker
Member Avatar
Resident Tinkerer
[ *  *  *  *  *  *  *  *  *  *  *  * ]
Edited yet again, for a complete re-writing, because it actually took me a 8 months(!) to realise that with the initial long and complex tutorial, the RL cars were handling like grandma’s station wagons instead of race cars.
I’m sorry.
This is a re-written tutorial – simpler, correct, and cars remain playable for both you and the AI.
(The Inertia calculating formula is still there, just not used anymore. I just didn’t want it to disappear completely from the Internet.)

See the first post of the thread.
- - - - -
And you don’t have to read all the text either.
Here are the quick instructions for the impatient (without all the “why”):
1) Divide EngineRate by 25.
2) Multiply the first Inertia value by 2.5 (3 fits Carmageddon cars, but not others) and the other Inertia values by 3.
Done! :)
(Optionally, you could also set ResMod to 1.0).
All my stuff is available here, and all my videos are available there.
-----
CW
Offline Profile Quote Top
 
Citywalker
Member Avatar
Resident Tinkerer
[ *  *  *  *  *  *  *  *  *  *  *  * ]
A little correction:
After extensive play-testing, I have found that for the first value, better RL inertia is RC x2.5, not x3. The second and third value are still x3, though.
First value x3 worked very well for Carmageddon cars, because of how they were in the original game, but others need x2.5.
I edited the first post and the last bump post accordingly.
All my stuff is available here, and all my videos are available there.
-----
CW
Offline Profile Quote Top
 
kay
Member Avatar
Re-Volt Chieftain
[ *  *  *  *  *  *  *  *  *  *  *  * ]
Always thanks for the hard work!
It wouldn't hurt visiting my blog or Re-Volt frontend's :)
Offline Profile Quote Top
 
1 user reading this topic (1 Guest and 0 Anonymous)
DealsFor.me - The best sales, coupons, and discounts for you
« Previous Topic · Car Tutorials · Next Topic »
Add New Reply