There is no doubt that it can be useful for a variety of different things.
But it does tend to go more naturally with a mesh modeler though, mainly because it is much easier to make it work well with mesh geometry.
With a mesh object if you move the control points of the mesh around, all the edges and faces move right along with it, there isn't any concept of there being an "underlying surface" that has separate trim edge structures on it like there is with a NURBS model.
With a NURBS model, you can't just move all the control points of the surfaces around and get a proper deformed result when an object is made up of multiple surfaces that share edges at trim curves - the surfaces can easily have control points that are not aligned with the trim edges, so if you just move surface points around the trim edges will tend to come apart in gaps.
There is a better description of this problem with some illustration (including showing how a gap gets opened by NURBS surface control point manipulation of a solid) here.
Luckily it is not all negative - this same structure that makes it more difficult to have deformations also is what makes booleans work really well with NURBS, since when pieces are trimmed the underlying surfaces do not get any more complex themselves and instead new trim curves are created. Those trim curves can also be removed later to recover the underlying surface.
Anyway I would definitely like to include these kinds of tools in the future, it is just not an easy area to work on so it may be a while.
- Michael |
