Damn, I'm trying to reply to this and I keep getting that dumb Admin Request
of type .....
Anyway, what I was trying to say, put a translation animation on the child,
Andre. It all falls apart pretty quickly.
> -----Original Message-----
> From: owner-xsi(at)Softimage.COM
> [mailto:owner-xsi(at)Softimage.COM] On Behalf Of Andre DeAngelis
> Sent: 28-February-2006 20:28
> To: XSI(at)Softimage.COM
> Subject: RE: rigging dilemma: driving a parent with
> attributes of the child
>
> Thanks Brent,
>
> I wasn't disputing Kims logic (I know netter than to take on
> Kim), but given Maya allows this to happen and that a
> simplistic test gave promising results in XSI, I assumed that
> some cycles can be tolerated more than others (as you suggest).
>
> Pre 5.0, cycle errors would pop up for apprently no logic
> reason. i.e.
> 2 objects in the a scene with no dependencis whatsoever would
> sometimes trigger this warning.
>
> Andre
>
> -----Original Message-----
> From: owner-xsi(at)Softimage.COM
> [mailto:owner-xsi(at)Softimage.COM] On Behalf Of Brent McPherson
> Sent: Tuesday, February 28, 2006 3:09 PM
> To: XSI(at)Softimage.COM
> Subject: RE: rigging dilemma: driving a parent with
> attributes of the child
>
> Andre,
>
> Kim is right and this is a cycle. (which can be verified by
> running "cycleCheck -all -dag -l;" in Maya)
>
> Now most cycles are bad because the result depends on the
> number of times it is evaluated. In a worse case scenario the
> cycle can create a feedback loop where the object flies off
> to infinity. (and beyond!)
>
> In the child/parent example given the position of the child
> is dependent on the number of evaluations. (so you might get
> different results playing back every other frame vs. playing
> back every frame etc.)
>
> However, XSI (and Maya) do allow cycles to be created because
> it is possible to create "stable" cycles that evaluate
> consistently or you might be able to plot the results for
> rendering etc. In general, though it is not desirable to have
> evaluation cycles in your rigs if you can help it.
> --
> Brent
>
> -----Original Message-----
> From: owner-xsi(at)Softimage.COM
> [mailto:owner-xsi(at)Softimage.COM] On Behalf Of Andre DeAngelis
> Sent: 28 February 2006 19:37
> To: XSI(at)Softimage.COM
> Subject: RE: rigging dilemma: driving a parent with
> attributes of the child
>
> Yes I relise that Kim,
>
> But having tried it and seeing hat it works (at least in a
> simple test), I am wondering what makes this colution less
> than desirable.
>
> Andre
>
> -----Original Message-----
> From: owner-xsi(at)Softimage.COM
> [mailto:owner-xsi(at)Softimage.COM] On Behalf Of kim aldis
> Sent: Tuesday, February 28, 2006 2:29 PM
> To: XSI(at)Softimage.COM
> Subject: RE: rigging dilemma: driving a parent with
> attributes of the child
>
> Because the rotation of the parent is driven by the child,
> but the rotation of the parent affects the position of the
> child, which then affects the direction of the parent, which
> affects the rotation of the child .....
>
> > -----Original Message-----
> > From: owner-xsi(at)Softimage.COM
> > [mailto:owner-xsi(at)Softimage.COM] On Behalf Of Andre DeAngelis
> > Sent: 28-February-2006 19:04
> > To: XSI(at)Softimage.COM
> > Subject: RE: rigging dilemma: driving a parent with
> attributes of the
> > child
> >
> > There is only one parameter dependency here.
> >
> > If you parent one null to another and then apply a direction
> > constraint to the parent (to point to the child) it workd
> just dandy.
> >
> > In fact, you can continur to rotate the parent in branch mode, to
> > offset the whole set-up.
> >
> > Am I missing something here?
> >
> > -----Original Message-----
> > From: owner-xsi(at)Softimage.COM
> > [mailto:owner-xsi(at)Softimage.COM] On Behalf Of kim aldis
> > Sent: Tuesday, February 28, 2006 1:48 PM
> > To: XSI(at)Softimage.COM
> > Subject: RE: rigging dilemma: driving a parent with
> attributes of the
> > child
> >
> > I'd be intrigued to see how, as rob says, the child is dependant
> upon
> > the parent which is dependant upon the child, which is
> dependant upon
> > the parent which is dependant upon the child which ...... And the
> > whole thing rapidly crawls up it's own arse. Whichever software you
> > use.
> > Would have been the same in SI3D too.
> >
> > > -----Original Message-----
> > > From: owner-xsi(at)Softimage.COM
> > > [mailto:owner-xsi(at)Softimage.COM] On Behalf Of David Gallagher
> > > Sent: 28-February-2006 18:39
> > > To: XSI(at)Softimage.COM
> > > Subject: Re: rigging dilemma: driving a parent with
> > attributes of the
> > > child
> > >
> > >
> > > Maya has its benefits. It handles this situation better
> > unfortunately.
> > >
> > > > I don't see how you can avoid a cycle.
> > > >
> > > > As soon as you tranlsate the child in negative Y the
> > parent rotates
> > > > causing the child to move causing the parent to rotate
> > causing the
> > > > child to move...
> > > >
> > > > _rob
> > >
> > >
> > >
> > > --
> > > David Gallagher
> > > Animator, Blue Sky Studios
> > >
> > > ---
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