Actually, it's about attaching a NURB Curve to a NURB Surface, but my mind first saw a Spoonerism there in about 4 seconds, and i almost couldn't write down (due to laughing) what i was visualizing... Anyway, would anyone here find this useful in CAD programs?

http://newavesys.com/news.htm

"ProSurf 3 is a full capability trimmed NURB surface modeling package. It even includes capabilities not found in any program at any price. For example, imagine being able to attach a NURB curve to a NURB surface in one step, marking it as a trimming curve, and then dynamically dragging the curve and watching the trimmed surface update in front of your eyes! You can also grab any point on the underlying NURB surface and edit its shape. No un-trim and re-trim is necessary. Add rendering, extrusions, skinning, shelling, reverse engineering, 3D bonded, editable solids and you will see the direction we are heading. All of this on top of our unique use of edit points ON the NURB curves and surfaces and all of our detailed shaping and fairing tools! "

I wonder whether the ACIS/Spatial kernel can do that, or if it is reserved for specific clients or classes of CAD ware. In the meantime, for generic presentation purposes (not hydros), i imagine that cutting or view planes might suffice. Any comments or visualizations of how VCP could exploit such a feature?

Now, if Punch! partnered with newavesys, there could be hydro- AND aerodynamics-tuned CAD. However, the user might pay a much higer price unless the digital modeling could be marketed successfully toward sailing and aero model enthusiasts.

But, as to the kernel, could a surface drawn and used (instead of a cutting plane being used) be trimmed by the boundaries of the other shape (say a cube, sphere or "extrapolatable-but-not-to-crazily-shaped" surface/solid, and then be made usable? I'm thinking the resultant trimmed surface might be more faithful/accurate in tangency than a line projected. But, i could be wrong.