From:  Michael Gibson
1184.4 In reply to 1184.3 
Hi Petr!

> By the way, when I make a circle it is a "perfect" NURBS with eight control points.

Yup - actually the exact NURBS circle has 9 control points, the start and end one will often look like one point because they are stacked up on the same location.

> As soon as I turn the control points on, I can see a different structure of
> control point, in order to edit the circle smoothly (you mentioned this
> mechanism previously...).

Yup, for curves this will happen for exact rational circles, arcs, and ellipses.

> This is the same for a sphere, cylinder, torus, cone, truncated cone after
> shrinking a conical trimmed surface, etc., isn't it?

Yup, there is an equivalent thing for surfaces. This will kick in if the surface is untrimmed (because the squishy version has a different parameterization - this is why shrinking the truncated cone is necessary before it will kick in), and then it detects if it is a surface of revolution, with a full 360 degree angle. If it is then it will do the "implicit replace with squishy version".

At some point in the future when I have some kind of properties panel for objects, I might be able to expose some "detailed properties" for these things that would let you turn this mode on or off for individual objects and adjust the squishy replacement point count.

- Michael