variable timestep and car physics

[David-Luis]

There is a bug that make the wheels and the car body make strange movements when use a variable delta time.

Here is a demo: (takes a few seconds to load)
https://dl.dropbox.com/u/28132609/demo_car_away/index.html

Use arrows to control the car. You can see the bug when the car is turning.

Best regards

[muzerly]

How you set the time step? it's must small enough make the simulation precise.

[David-Luis]

I use this code:
_physicsWorld.step(elapsedTime, maxSubStepsPhysics, _timeStep);

where:

maxSubStepsPhysics:int = 3
_timeStep:Number = 1/60
elapsedTime = varies between 1/30 - 1/60
(I updated the demo, to make sure the value is between this values, you have to clear the browser cache)

I'm using Away3D 4.1 and AwayPhysics v1.0 alpha (13-11-2012)

[muzerly]

not sure what cause this, you can try to adjust some property of AWPWheelInfo, like damping, friction etc.

[David-Luis]

The problem is not on that values, is the use of variable step. If I use fixed step, the problem doesn't appear:

_physicsWorld.step(_timeStep, 1, _timeStep);

where:
_timeStep = 1/60

You can see it in this demo:
https://dl.dropbox.com/u/28132609/demo_car_away_fixed/index.html

[lo-th]

you find solution in this thread
http://away3d.com/forum/viewthread/4014/

in AwayPhysics.c
line 944
vehicle->updateWheelTransform(j,true);
change to false and rebuild swc with flascc

On Wed, Mar 13, 2013 at 1:16 PM, louis87 [email protected] wrote:

The problem is not on that value, is the use of variable stop. If I use
fixed step, the problem doesn't appear:

_physicsWorld.step(_timeStep, 1, _timeStep);

where:
_timeStep = 1/60

You can see it in this demo:
https://dl.dropbox.com/u/28132609/demo_car_away_fixed/index.html

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LoTh - Freelance flash as3 / 3D
website http://perso.numericable.fr/chamaslot/ |
bloghttp://3dflashlo.wordpress.com

[David-Luis]

ok, thanks!