I can think of two ways I might approach this.
- There is a trick you can you use with lattices. If you scale some segments to zero, and set the FFD to “All”, you can make a lattice that “eats” geometry as you move it through it. You could set this up before the bending deformation as a way to fake scroll it away.
And to be game-engine friendly, you could add this effect to a ribbon IK, which carries some follicles and bones, which then deforms a polygon asset. The lattice would just scale the ribbon, and you could bake down the bone results.
- And I think this would be an easier approach, where the ribbon always stays extended, so it is intuitive and easy to animate:
Again, using follicles, you could set up a driven key (or whatever) that animates some follicles sliding along the surface, scaling it to zero. The ribbon IK itself wouldn’t scale at all, but the geometry would slide along it. Again, bake out the joints, and it is game-engine ready.
In this gif, it looks like it is scaling instead of sliding, but I think that is because I had some distortion on my nurbs plane.
(Edit: Nope, it’s just the way I set keys on the follicles. They have to be animated with the same keyframe slope, then they slide.)