speaking of the chain implementation in XSI.. I was curious if any of you ever use the break chain at bone command. Is it just me, or is it perhaps the most useless skeleton tool in the arsenal..
Adam
----- Original Message -----
From: brad friedman <xsibrad(at)fie.us>
Date: Sunday, January 29, 2006 8:23 am
Subject: Re: suggestion: force ik_fk
> The problem Brad, is that if I request it too, they'll just assume
> that rigging guy Brad has two e-mail addresses and chooses poor
> secret aliases :)
>
> I do think you are correct about IK needing to be broken off of
> the bones. Though, the thing I do like about their current
> implementation is how "smart" they are about IK FK blending on the
> mixer and timeline. It has a knack for ignoring the phantom limb
> and just doing quaternion blends, when it can. I think a lot of
> that ability to treat bones different, comes from the fact that
> the bones are a separate object type. I think it would be
> important to try to keep that functionality if it moved over to a
> coinstraint implementation. I think also the ability for the
> effector to snap back to the end of the last bone when released is
> important. And I would be extremely happy if choosing an object
> as an end effector for an IK constraint, optionally changed its
> manipulation behavior to snap.
>
> The funny thing is, I think Blender just changed their animation
> system to go the other way. IK was a constraint, and now its not.
>
> Ah well, I'll probably just have to give up this dream of using
> the internal IK/FK blend and make a compound leg as usual. Thanks.
>
> -brad... erm... no... I mean... Fred!
>
> brad <brad(at)cg-soup.com> wrote:
> For me, the current IK/FK implementation in XSI has reached a
> dead end, but that's probably just me. To most animators, looking
> at the current set of IK chain options is a daunting experience.
> Rather than adding more controls, I'd prefer a rethink of IK that
> simplifies the interface and expands our abilities.
>
> As an XSI rigger with a reputation for experimentation, invention,
> and high end production experience, here's where I am with respect
> to IK in XSI:
>
> -I only bones when it is necessary to solve for IK. They can
> become processor expensive in large numbers.
> -I rarely use 3D chain behavior.
> -I rarely use IK on more than 2 joints. I may use multi-bone
> chains, but they are almost always constrained to curves or
> manipulated by expressions.
> -I always provide an outlet for blending from IK into FK or other
> control setups
> -I am frustrated by the fact that IK can only be associated with
> special scene objects... bones.
>
> What I'm hoping for Softimage to do, and I've put in a formal
> request, is to have simple, 2-joint IK behavior abstracted out
> into a constraint operator. Applying and removing IK should be the
> same workflow as applying or removing constraints. And as
> constraints, the IK constraint should behave the same as all other
> constraints in XSI where you can apply as many as you want to the
> kinematic stack, and blend them any way you need. You should be
> able to store them into Action sources and control them from the
> mixer.
> However, as with any functionality, it has to be more than one
> person making the request. As long as it's just me, the idea of
> the "IK constraint" is going to be low priority in the huge pile
> of feature rec's. :-)
>
> -Brad
>
> > -------Original Message-------
> > I was putting together a hybrid IK/FK reverse foot rig on friday
> when I
> > noticed some odd design choices with the integrated IK/FK
> blending in XSI.
> > It brought on some questions and ideas.
> >
> >
> > previously, I had assumed a chain has three states of manipulation
> > behavior... unkeyed hybrid ik/fk... keyed ik, and keyed fk. I
> had been
> > going by the assumption that the way to get between these modes
> was by
> > keying the IK/FK blend, to IK, FK, or not at all. However, it
> turns out
> > there is a fourth state... when you key the ik/fk blend to fk,
> but have
> > not keyed the rotations of the bones yet. In this mode, the
> bones can be
> > rotated. however, if you pull their root, they snap to their end
> effector> as if they were in IK mode ( if the effector is
> constrained).>
> >
> > now, these crazy cool but sometimes annoying hybrid manipulation
> modes> seem to have prompted the inclusion of the "Forc! e IK" switch.
> > However, there is no "Force IK/FK" switch which eliminates all
> the other
> > weird semi modes and leaves the bones in either pure IK or pure
> FK based
> > on the blend, without keys.
> >
> >
> > My frustration is that I can't create a rig that uses the
> internal XSI
> > IK/FK switching that acts correctly when it comes in without
> keys. It
> > seems silly to me to have to have fcurves on my legs in order
> for them to
> > act correctly.
> >
> >
> > So, anyone have any thoughts? Unless I'm missing something (entirely
> > possible) it seems to me there need to be a "force IK/FK" switch
> on there
> > so I can constrain the IK leg but blend it to the FK leg which
> is totally
> > free, due tp ignoring the constrained end effectors completely,
> without> the need for fcurves to be on the rig already.
> >
> >
> > btw, please don't tell me "just make a compound leg." I know that
> > already. The point is to make one that u! ses pure internal XSI
> IK/FK> blending.
> >
> >
> > Thanks.
> >
> >
> > -brad
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