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Handling - Acceleration Experiments

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BenMillard
  • BenMillard

    aka Cerbera

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#1

Posted 06 August 2005 - 11:04 PM Edited by Cerbera, 24 December 2005 - 10:19 PM.

NOTE: This tutorial is a re-formatted version of my GTASA Handling: Acceleration tutorial and the web page will be updated from the discussions in this thread. There have been a lot of topics on the forums on this subject, so hopefully having this guide will make forum searches bring up the information people are looking for rather than having to hope Project Cerbera appears from a Google search.

(Hopefully the topic title and description match whatever the current forum convention is, since the Tutorial Presentation thread was never updated from the obsolete format.)


GTASA Handling: Acceleration
Acceleration in GTASA works differently to previous editions. My tutorials about acceleration and detailed acceleration in GTA3 and GTAVC show a very different system to GTASA.

The relevent values in GTASA handling.cfg work like this:-
  • Top Speed does not change anything unless you enable the USE_MAXSPD_LIMIT flag in the HandlingFlags setting.
  • Drag Multiplier does change acceleration.
  • Drag Multiplier does change top speed.
  • Mass does change acceleration.
  • Mass does not change top speed.
  • Engine Inertia does change acceleration.
  • Engine Inertia does not change top speed.
  • Acceleration does change acceleration.
  • Acceleration does change top speed.
There are some interesting features of the gameplay as well:-
  • Driving up hills does reduce top speed.
  • Driving down hills does not increase top speed.
  • Driving up or down hills does change the rate of acceleration.
  • Leaning forward slightly on motorbikes does increase top speed.
  • Retracting the landing gear of planes does increase top speed.
  • The maximum possible speed of vehicles in the game seems to be 287km/h which is about 178mph.
Flying vehicles have special data in the handling.cfg file where you can set how much the drag is reduced by retracting the landing gear. The effect of special data on acceleration is not covered in this tutorial.

Preparing for Experiments
All the experiments on this page are based on a completely original "Taxi" handling line. The "Taxi" is the modern yellow one - not the old "Cabbie" car. The original handling for the Taxi is:
CODE
TAXI 1450.0 4056.4 2.2 0.0 0.3 -0.25 75 0.80 0.75 0.45 5 180.0 19.0 10.0 F P 9.1 0.60 0 35.0 1.4 0.1 0.0 0.25 -0.15 0.54 0.0 0.2 0.51 20000 0 200000 0 1 0



Effect of Engine Acceleration on Top Speed
user posted image
More acceleration means a higher top speed, as you would expect. However, there is an artificial limit to the maximum speed a vehicle can reach. This is partly based on the Drag Multiplier, which is tested next.

Effect of Drag Multiplier on Top Speed
user posted image
With a value of "0" for Drag Multiplier the Taxi reached a top speed of 214km/h but with no drag, the car should just keep getting faster and faster. Obviously the game is preventing the car from going as fast as it should do. Using a value of "1.0" for Drag Multiplier gives the same value as "0" so it seems values below "1.0" are assumed to be "1.0" to prevent high speeds being reached.

With a large Acceleration value and a low Drag Multiplier, it might be possible for cars to reach the 270km/h limit which planes have.


Normal Taxi Acceleration Curve
user posted image
Now the experiments go from top speed to the way the car accelerates. By comparing this curve of the standard Taxi acceleration to the graphs below, you can see the different effects of different parameters.

Effect of Engine Inertia on Taxi Top Speed
user posted image
This seems to be the key value to better acceleration curves. A higher Engine Inertia value will make acceleration more gradual without lowering the top speed. Unfortunately, the limited top speed makes the car suddenly stop accelerating when it should gradually stop accelerating.

Effect of Drag Multiplier on Taxi Acceleration Curve
user posted image
We have already seen the effect of Drag Multiplier on top speed, so here we see how it effects the way the car accelerates. Basically, a high drag makes the vehicle accelerate more slowly and reach a lower top speed. Interestingly, a low Drag Multiplier means the car takes longer to reach its top speed, which is increased. Another important part of realistic acceleration.

Effect of HandlingFlag Boosts on Taxi Acceleration Curve
I have not experimented with this yet.


Realistic Acceleration?
Perfectly realistic acceleration is not possible in GTASA but it is possible to get a semi-simulation style of acceleration. It can be made better than I my GTA3 Handling Overhaul and the more recent GTAVC Handling Overhaul did it, too.

To make acceleration more real:-
  • Enable the USE_MAXSPD_LIMIT flag so that the special acceleration mode is used.
  • Use a Drag Multiplier value of "1.0" to get higher top speeds since the original setups all have very low top speeds.
  • Use a much higher EngineInertia value to make acceleration more gradual. Most of the original setups reach top speed far too quickly.
  • Use roughly the same Engine Acceleration. This is so the acceleration force matches the available grip.
  • Use a lower Braking Force.
Since slowing down is just negative acceleration, it deserves attention. Nearly all the original setups will cause the wheels to stop moving when you use the brakes, which makes the car impossible to turn. I set the braking force lower, so the wheels can just about keep moving when you use the brakes. This allows you to turn a little while braking, giving more realistic control over how you enter each corner.


(EDIT) Acceleration of 100.0 and Drag Multiplier value of 1.0:
user posted image
800 x 600 - kB.

This seems to be the maximum speed which a car can reach without enabling the USE_MAXSPD_LIMIT flag.

When the USE_MAXSP_LIMIT option of the HandlingFlags value is set, the vehicle's acceleration curve will be stretched to try and reach the Top Speed setting. However, if there is not enough acceleration then the vehicle will never actually reach the Top Speed limit. Setting the acceleration so that the car gets close to the limit without reaching it enables realistic acceleration. You need a very high Engine Inertia (about 100!) to keep the acceleration rate sensible.

The result is acceleration a bit like you get in Gran Turismo. I am currently working on custom handling for the Infernus and Turismo using this new technique.

_MoNoXiDe_
  • _MoNoXiDe_

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#2

Posted 09 August 2005 - 08:17 PM Edited by _MoNoXiDe_, 09 August 2005 - 08:47 PM.

wow thats great, however, i managed to succeed the top speed you mention, I managed to get up to 341mph (545.56 km/h) using USE_MXSP_LIMIT handling flag smile.gif

Also thanks for this information very useful though some parts i believe inaccurate, the drag information you supplied allowed to me to reach such speeds which i found very useful. However when i set the drag multiplier to 0.0 the car wouldn't spawn. I could never reach above 260mph before without the fact of knowing the details of the drag multiplier. I appreciate the effort thats been put in, good work wink.gif

user posted image
crazy stuff

BenMillard
  • BenMillard

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#3

Posted 12 August 2005 - 04:23 PM Edited by Cerbera, 23 August 2005 - 05:20 PM.

I am now developing my GTASA Handling Overhaul which already has many completed handling lines for the original GTASA vehicles.

Changes from original handling:-
  • Completely re-worked acceleration with the USE_MAXSPD_LIMIT flag to make it more progressive. 0-60mph times are pretty close, as are the 0-100mph times.
  • Top speeds match real performance. Turismo just about reaches 200mph if you run it for long enough. Banshee gets about 160mph and the Infernus gets around 170mph.
  • Reduced traction settings and changed traction bias to better reflect real performance.
  • New spring and damper settings to reflect vehicle roadhoalding.
  • Adjusted ride height and suspension travel so that Turismo and Banshee don't look like off-road trucks any more.
  • Mass is now closer to the real vehicle settings.
  • Braking retuned so that tyres do not stop turning when brakes are applied. If you brake while turning the car will skid a little as the tyres lose grip. Careful use of braking and turning allows for drifting into corners like in serious racing simulators.
These handling lines are not perfect. It's somewhere between Need for Speed 2 in Simulation mode and Gran Turismo 2 in the career mode (not arcade) and that's about as good as you can get in GTASA, from what I have found.

To get the highest top speeds, drive North from Los Santos International Airport over Mulholland Intersection, across The Mako Span and all the way to the end of Harry Gold Parkway in Las Venturas. R* setups always reach top speed in about 10 seconds, these cars will still be accelerating slightly after a whole minute.

(EDIT) Reduced traffic is cheat THGLOJ. All traffic are fast cars is GUSNHDE. Very useful when testing handling.

Kuro
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#4

Posted 17 August 2005 - 04:10 PM

Just done driving these 3 with cerbera's setup and i must say that this is great improvement comparing to default san andreas handling, sheer joy smile.gif Noticed some similarities with real world counter parts, for example, dodge viper(banshee) is a bit oversteery and f40(turismo) has that feeling of downforce with high speed. Overall, i think this is very close to realism limits of sa engine. I would like to hear however what other people think, more feedback!

CygnusX
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#5

Posted 23 August 2005 - 03:43 PM

Just tried that stuff too and I must say, amazing! It's exactly what I've been trying to do the last few weeks. Great job, keep it up!

michael-z
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#6

Posted 30 August 2005 - 02:20 AM

can you do that with a plane to? notify.gif

muzzman89
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#7

Posted 13 October 2005 - 12:39 PM

hey guys i have been tweeking the bullets handling an i achieved 866kp/h!!!!!!! i hit the jump thing in the desert air port and i landed in the woods somewhere in LS!

BenMillard
  • BenMillard

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#8

Posted 13 October 2005 - 05:35 PM

This topic is not updated any more. The web page linked at the start of the first post has the most recent version. I recently updated it saying how top speeds work in the normal acceleration mode. I've managed about 960km/h using my super high speed handling for the Infernus. Using a bigger acceleration value and a higher TopSpeed setting would allow for even higher top speeds.




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