[ODE] V0.8+ Bugs Update (Att: Bram)

[Viper]

Hi,

I've got some feedback regarding a couple of possible bugs I posted on the bug tracker a while back. I didn't get chance to reply before the tracker threads were closed unfortunately.

First the hinge motor issue:

[ 1661687 ] Hinge joint motor not working (V0.8)
http://sourceforge.net/tracker/index.php?func=detail&aid=1661687&group_id=24884&atid=382799

Initially I'd assumed the hinge motor was not functioning at all in V0.8, looking at the problem a little closer revealed why. The test I used was a simple pivoting ramp with a hinge joint at its center using a mass value of 100.0.

In ODE builds V0.5, V0.6 and V0.7 applying the following hinge force/torque results in the ramp tilting gently until it hits the joint stops...

dJointSetHingeParam(HJoint,dParamVel,-1)
dJointSetHingeParam(HJoint,dParamFMax,10)

However, in build V0.8 the above force/torque does not move the ramp at all, hence the (wrongful) assumption the motor wasn't working. In fact it doesn't behave the same until you increase the torque significantly like so...

dJointSetHingeParam(HJoint,dParamVel,-1)
dJointSetHingeParam(HJoint,dParamFMax,400)

So, did the previous builds have a problem with the hinge motor which has now been corrected, or is this discrepancy due to a possible bug in the V0.8+ builds?


Next the mass translate issue:

[ 1661685 ] dMassTranslate not working (V0.8)
http://sourceforge.net/tracker/index.php?func=detail&aid=1661685&group_id=24884&atid=382799

You stated in the tracker that the dMassTranslate function name is misleading. If that's the case then the official user guide is also misleading in its description of the function... "Given mass parameters for some object, adjust them to represent the object displaced by (x,y,z) relative to the body frame."

Previous builds allowed the use of this function, but V0.8+ doesn't allow any values other than 0,0,0.

The question I'm raising here is, if it doesn't accept any values other than 0,0,0 then what exactly is the purpose of the dMassTranslate function?

If it can't accept any other value than 0,0,0 then why have it at all?


Thanks for looking into these on the tracker earlier, I'd just like to clarify these two issues if possible.

Kind Regards,

Jim Williams
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