I am a bit stuck with a problem and I'm hoping someone can help me out. I am creating a "growing" extruded surface animation using the path and profile curve. I'm using the subCurve Max value of the extruded surface to animate the growth. I have both flat and tube surfaces on separate curves. I would like to add some twisting in a few spots, especially on the flat surface to give it a ribbon-like quality, but I can't seem to figure out how to do this. I've tried rotating the CV's of the surfaces, but it causes some unwanted shearing during the animation. Any ideas?
One way you can achieve the effect you're after would involve putting a lattice around the curve, then rotating the lattice along those stretches you want the extruded surface rotated. The lattice should be a deformer for the final, extruded geometry, of course.
To make it easier to create and position the lattice, you might look into setting up a path animation along the same path, then using the Flow Path Object setup, which can create a lattice which runs the length of a curve.
I feel like I might be missing an easier, simpler way to do it, too, so maybe someone else has some suggestions.