FK transform at SOP level.

[hopbin9]

Hi,

I have to do an animation at the SOP level that looks like forward IK. Using three boxes linked together to form a simple arm. It needs to be at the SOP level because I'm using mirrors and stuff on the output geometry.

So I can animate the first box using a transform, but the second and third transforms don't update their pivots based upon the previous transforms (I isolate the rotations to each box using groups).

I've tried to write expressions in each transform to reference the previous to update the pivot locations, but I'm not having any luck on figuring out what the expressions should be.

Something like..

pivot = "vector([0,2,0]) * (previous-transform-matrix)"

Since a "transform" node at the SOP level isn't a scene node. I don't know how to get a matrix from it.

Any help would be great.

Thanks,

[hopbin9]

Oh, I figured out some sort of hack.

Off to the side I use the Add SOP to create a single point, and then transform that point to the locate of a pivot. Then in the transform of one of the boxes I use the Point(..) expression to read in that point as the location for the pivot.

Works good for the second box in the chain, but the third gets a little more complex but still do able. Seems to be working now for me, but is there an easier way?

Thanks,

[digitallysane]

Isn't it easier to do the animation at the Object level then ObjectMerge all the animated objects into another object and do your SOP stuff there?

Also check the Align SOP, it might be of help.

Dragos