[vtkusers] SetUserMatrix- ignored by the Renderer

[Andrew Dolgert]

The code you've shown should work fine.  That's what's confusing.  I use
code which sets a new user matrix before each redraw.

Inside of vtkProp3D, the Matrix4x4 gets hooked to a
vtkMatrixToLinearTransform and then to the UserTransform.  Any updates
on the matrix should, and usually do, transfer all the way to the
Actor's transformation.

Maybe you could try putting the matrix into a transform and calling
SetUserTransform?  Maybe you could make a new Matrix4x4 each time
through the loop?  Maybe it's something else?

- Drew