Unwanted Split of Loft Surface


#1

Hi there, I’m just trying to do a fairly rudimentary loft, but would like to keep the result as a single surface (or understand why this isn’t possible). I have a line lofting through and arc and back to a line again (the surface in the image below).

  1. Shows the starting condition.
  2. I loft from the edge of the plane, through the arc and on to the edge of the opposite plane. This results in a polysurface, which is split longitudinally through the centre.
  3. I loft from the edge of the plane to an extruded version of the arc. This results in a single surface, which I could mirror to get the other half.
    Note: I am using the “Match start tangent” and “Match end tangent” options.
    The question is this: is it possible to achieve this with a single surface?
    Cheers, Steven

170515 Split Surface.3dm (146.5 KB)


(David Cockey) #2

Use MergeSrf with Smooth=No on #2 or #3 to obtain a single surface. (Smooth=No in MergeSrf is essential to keep the original shape.)

I have no idea why the Match start tangent and Match end tangent options result in a polysurface.


(Vanessa Steeg) #3

Hi @Steven

If you rebuild the arc to 6 ctrl pts / degree 5 and then Loft it, with Match start and end tangent, you should get a single surface.


#4

It would also be a good idea to add a “through curve” command to the “BlendSrf” command, a condition that allows creating a surface passing for a data curve with a continuity condition at extremes (up to G4).
I had proposed it to developers several years ago …