NURBS curves: option for spline to snap to points
A certain other major 3D software's equivalent of NURBS curves has two modes: CV (control vertex) and EP (edit point). (Don't ask me about the logic behind the naming.) The difference between them is shown in this image.
Essentially, CV sort of averages between the points, while EP makes sure that the spline actually snaps to each point.
Currently, Blender only has CV.
Why does this matter?
It is common practice in rigging to use NURBS curves for spline IKs, with the curve's points directly parented to the handles that the animator works with. When setting this up, it is best to parent EP points to the handles rather than CV points, because animators expect for the geometry to go exactly where they put the handles.
The mockup I made below sort of shows what I'm talking about. The first image shows the only behavior Blender can currently produce with spline IKs. The second image is a faked demonstration of what animators want but which is currently unachievable (ignore the head; it chose to do its own thing).
As far as implementation goes, I could see this potentially being a toggle in the Active Spline panel in the Curve data. Alternatively, in the Other Software That Shall Not Be Named, just like you can choose to edit the vertices, edges, or faces of polygonal meshes, you can similarly choose to edit the CVs or the EPs of a curve.
3 Comments
I agree with the point of the suggestion, but will just note that CV and EP are two different types of curves; it's not just a "user visual" of where the control points are located.
That's what I thought at first, until I realized that the Other Software That Shall Not Be Named offers them as two different ways to edit the same spline. The confusion probably comes from the fact that for creating the curve in the first place, it offers either the CV Curve Tool or the EP Curve tool, which make it seem like two different kinds of curves, but in reality it's just two different approaches to creating the curve, either placing its CVs or its EPs. Once you create a curve with the CV Curve tool, you can then choose to edit its CVs or its EPs, and vice versa (although the CV Curve tool only generates EPs for the start and endpoints of the curve).
That's not to say it necessarily has to be that way in Blender; like I said in the post, I'd be just as open to Blender treating it as two different subtypes of NURBS, or two ways of generating a spline from the same control points.