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Bullet Units

Posted: Tue Jan 06, 2015 12:00 pm
by Granyte
I was wondering how does the rigidbody linear velocity scale.

I mean how many bullet units per second or per ticks does that represent cause currently I have an issue balancing acceleration in my game because of this

Re: Bullet Units

Posted: Tue Jan 06, 2015 12:18 pm
by xexuxjy
Gravity is set at 9.81 so the units are effectively meters even if it's not really mentioned as such.

Re: Bullet Units

Posted: Tue Jan 06, 2015 1:45 pm
by Granyte
Ya but in the case of pure size units it's perfectly reasonable to assume meters. But other units can fit as long as they match what you need.

But when talking about acceleration or velocity the the result are in (Bullets unit of scale)/(Bullet unit of time)

but how much units of scale does a linear velocity of 0,0,1 get you acros in ? units of bullet time

Re: Bullet Units

Posted: Tue Jan 06, 2015 1:57 pm
by xexuxjy
Ah sorry, ok.
It depends on what you're feeding into stepSimulation , which has defaults of 1/60th second for splitting simulations steps (btDynamicsWorld.h)

Re: Bullet Units

Posted: Wed Jan 07, 2015 5:56 am
by Granyte
so if I step my world in 1/60 of a second I should have a match of 1 units/1 second

Re: Bullet Units

Posted: Fri Jan 09, 2015 10:53 am
by ratatouille
Please see this thread for my simulation of a damped pendulum:

http://www.bulletphysics.org/Bullet/php ... =9&t=10184

Accuracy was very good in the end, with MKS units. However, world scaling is not yet working (e.g. simulating a very tiny pendulum), am about to launch another thread on that.