View Full Version : "Match Goal Orientation" -- passing this back down the bone chain?

09-17-2015, 01:13 PM
Been working on my pretty much nil IK skilz. Rigging a cord as part of a lamp, simple bone chain IK'd to a null parented to the pivoting lamp reflector head. That is, the cord exits the boom, curves around a very short bit, and connects to the pivoting reflector. Parented a null to the reflector to serve as an IK target.

Needed to turn on "Match Goal Orientation" to get the final bone to correctly enter the reflector. Works. However, see the JPG, the orientation doesn't seem to get passed down the bone chain-- only the final bone is rotated to match the goal orientation, and this rotation doesn't seem to affect the next bone in the chain.
How do I get a nice soft falloff from the final bone, rotationally, to the next 2 or 3 bones in the chain?


09-17-2015, 01:30 PM
Not so straightforward. You have to get the rotation at the end as seen from the base of the chain and constrain that into each of the intermediate bones in the chain incrementally, ensuing that you've gotten the whole chain designed (co-ord wise) such that the constraint can properly operate within the rotation domain.

09-17-2015, 03:26 PM
You might change the original position of the reflector (and thus its child Goal null) so the orientation of the Goal is straight down the cord, and then rotate the reflector into position as a preliminary (non-rendered) setup move. I.e. setup the reflector straight up for frame 0, then orient it at frame 1, but don't render frame 0.

For the existing reflector / goal / bone setup, I don't know if it'd work, but you might try reducing the Strength of the 2nd and 3rd bones down the chain and maybe increasing the Strength of the oriented bone so the oriented bone has more influence over the mesh around those bones. The 2nd and 3rd bones themselves wouldn't match the Goal orientation, but the mesh might look a little less abrupt making the transition to the last bone. You could also try the same with a Weight Map on the mesh influenced by the last bone which bleeds over down the mesh around the 2nd and 3rd bones.