Vern,
I had a gut feeling and it came true. A very interesting IK-puzzle. I did enjoy.
A (partial) model: folding.3dm (366.8 KB)
and some comment: folding.pdf (358.3 KB)
Working on the model I think I came across your ‘pivot match up problem’. Indeed it seems quite impossible, using the BongoRotatePivot command, to orient the pivot of an object to a specific non orthogonal direction in space– at least that’s what I think you are trying to do: revolve a pivot with respect to the (slant) object it belongs to.
But, do not fear: the BongoMovePivot command has an option 3point. The help file explains:
Pick a location, a point on the x-axis, and a point on the y-axis to establish the new base and orientation for the pivot.
Obviously object snaps or other modeling aids can be applied. When the orientation of Y axis is irrelevant just click anywhere.
A somewhat strange place to look for 3D rotating, I admit. It might be logic to implement a similar 2point option in the BongoRotatePivot command.
A bit poor in the UserInterface department, I hear you say. Rhino’s CPlane_3Point at least visualizes the axes (although it takes some training to see what’s happening).
And/or it might be useful to add an (Orient) option to both BongoRotatePivot and BongoMovePivot command (or to make a specific BongoOrientPivot command) which works similar to Bongo’s Orient command. Reference point 1 is automatically the pivot’s origin (default position, if there is no pivot). While picking Reference point 2 - in this case the only one - an (X, Y, Z) option can allow to select a desired axis. Such a Orient option/command would come in very handy to align one of the pivot’s axes (the orientation of the others not being relevant) with a line object or the edge of a surface or polysurface.
I hope the Bongo team is reading along.
Luc