[ODE] Geom Transforms hate me

Panayoti pany2002 at urbansquall.com
Thu Sep 25 11:46:37 MST 2003


Hey slipch,

Thank you for your response.

"I am not sure I completely understand your problem.
First thing is that center of mass is always in the body position, and
you can not change it by  dMassTranslate (see docs). This function can
be used to shift mass in order to make right inertia tensor when you
add mass of geom which position shifted relatively to its body.

 P>      ...... dMassTranslate (&m,-m.c[0],-m.c[1],-m.c[2]);

 - This seems to be wrong because you shift the mass by a vector of
 global position."


I understand what mass translate does, I'm just not exactly sure what
the code in the ODE tests is doing. The code I cut pasted is directly
out of the construction of composite objects from the ODE tests... I
didn't understand the portion which I copy pasted, which, I am assuming,
is why I cannot get my own separate example to build the masses right
(the collision geoms show up great, but for some reason one side is
"heavy" when it should not be, implying I screwed up the mass
distribution somehow, at least that's what I am guessing).

Still stumped,

Pany




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