CGTalk - Problem with "link with orientation"

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Mechis

12-20-2007, 09:57 PM

I'm trying to use "link with orientation" to smooth out an elbow joint. However, when I do so, the points move back and forth when interpolating between the shapes (as if the points are overshooting b/c they interpolate past the keyframe).

If this were happening when I was keyframing a normal object, I would just open the animation mixer and set it to flat tangents or linear, so the curve wouldn't pass the keyframe... but I can't seem to figure out how to do that with "link with orientation".

Does anyone have any tips on how I can fix this? Should I keep trying to use "link with orientation"?

Thanks,
~Mechis

tuna

12-20-2007, 11:21 PM

Use plain old "link with.." instead, and just define the channel you want to link it with in the box it brings up, then you'll be able to use the animation editor to edit the relational f-curve.

Mechis

12-21-2007, 12:32 AM

Thanks for the quick reply, Tuna. I'm still not quite understanding what I'm supposed to do though. I've attached a sample scene file showing how far I've gotten.

I made the cylinder, enveloped it to the bones and made a cluster at the joint.
I selected the cluster, and linked it with the z rotation of the top bone
I rotated the bone 90 degrees and did "save deform key"
When I test it (scrub from f1-24), the points seem to pop in to place.

How do I get to the points' curves in the animation mixer, so that I can smooth out their motion? Thanks!
~Mechis

tuna

12-21-2007, 10:11 AM

Are you sure you used right click > "Link with..."? Because no graph comes up for your link, but when I delete it and make a new link, the graph works fine when i right click the "L" icon in the mixer and choose "Animation Editor".

Mechis

12-21-2007, 02:33 PM

Hey Tuna,

Are you sure you used right click > "Link with..."?
I think this is the problem. I was doing it this way: Deform -> Shape-> Deform Keys-> Link Deform with... It seems weird that different ways of accessing "link with" would create different results.

What exactly are you right clicking on though? I don't see a "Link with" option when I right click the cluster and there's no animation (green) chip that I can right click on.

Thanks so much for your help... it is super appreciated,
~Mechis

ps. I checked out the chest rigging video on your blog... awesome! How did you maintain the chest's volume when you rotated the controls? Is it via corrective morphs like I'm trying to do?

Mechis

12-21-2007, 05:31 PM

I'm still curious about what I'm doing wrong with "Link with", but I wanted to tell people that I found a different way to do this.

I made a bone at the inside of the elbow and set an expression to make the bone stretch based on how far the arm bends. Then I just do some careful weightmapping and the joint keeps its volume pretty well!

~Mechis

tuna

12-21-2007, 07:52 PM

Oh, sorry, I mean right clicking the [green part of the] actual shape weight in the animation mixer of the object. I'm really not too sure as to why different ways of accessing "link with" work differently in XSI.

The spine rig is nothing special, it's mostly just a "ribbon spine" setup with a few tweaks here and there to work in XSI. It was on a Maya rigging DVD I once saw (The name escapes me right now, but searching ribbon spine in google should help!)

Mechis

12-21-2007, 09:44 PM

Ok... I finally got it. Thanks for all your help, Tuna. I really thought I was going crazy. hehe...
~Mechis

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