Bug in PxQuat::toRadiansAndUnitAxis ?

Gaming and Visualization Technologies APIs Physics Modeling (closed)
#1

I am running into some puzzling behavior, where a slowly spinning box appears to pause after completing a full rotation. It seems the rotation is still simulated correctly, resulting in a constantly varying global pose PxTransform obtained for the shape. However, the angle of rotation obtained from the q member of this transform, remains at a constant value of 3.14… when the box is on its second rotation. To reproduce:

aBoxActor.setAngularVelocity(PxVec3(0,0,1)); // assume aBoxActor previously created with a single box shape
PxTransform pose = aBoxActor.getGlobalPose();
PxQuat Q=pose.q;
PxReal angle;
PxVec3 axis;
Q.toRadiansAndUnitAxis(angle,axis);

Set a breakpoint after the last line. The angle variable will correctly change at about one radian-per-second, for a while, then remain fixed for a same amount of time, then repeat this behavior periodically.

Am I using this feature incorrectly or is this a bug? The reason I need the angle/axis representation is that this is the most convenient way to transform the Modelview matrix in OpenGL.

Thanks,
-nuun

#2

Hi,
That is troubling, I’ll try to reproduce it and get back to you ASAP.
Thanks,
Mike

#3

Got it. It was indeed a bug, fixed in version 3.2.2. I can’t get 3.2.2 to play nice with the Windows runtime dll (I’ll start a new thread about this if I can’t figure it out), but I can keep using 3.2.0 and modify PxQuat.h as follows:

//angle = w<quatEpsilon ? PxPi : PxAtan2(s2*s, w) * 2;
  angle = PxAbs(w)<quatEpsilon ? PxPi : PxAtan2(s2*s, w) * 2;