Sweep1, output brep surface problem

Hey guys,

The sweep1 function gives everyone head aches sometimes, but today i found something really awkward:

I have a polyline as section curve and a planar curve as rail curve as the inputs for my sweep1.

You would expect that the output is Brep, instead it gives me an untrimmed surface, even when I explode the outcome it still says untrimmed surface.

When I bake the outcome it gives me the desired polysurface/brep, no weird stuff. The weird thing is that grasshopper thinks it's an untrimmed surface.

I wrote a custom sweep1 in python as well as an explode brep -> same result. It gives me an untrimmed surface. see attached screenshot:

Is this a common known problem or just me?

Thanks!

Replies to This Discussion

Permalink Reply by David Rutten on February 20, 2013 at 4:00pm

Just like it's possible for a single nurbs curve to have sharp kinks in it, a single nurbs surface can have sharp edges on the interior. There's nothing intrinsically wrong with this though we (McNeel & Associates) tend to dislike this*.

When you have a surface which you feel should have been a Brep with multiple faces, then you can call the SplitKinkyFaces method:

Dim B As Brep = Brep.CreateFromSurface(Nothing)
B.Faces.SplitKinkyFaces()

David Rutten

david@mcneel.com

Poprad, Slovakia

* We also dislike nurbs geometry that has a domain that is wildly different from the size of the object, meshes that have vertices that are not connected to any faces and surface trims that intersect surface edges, even though all of these are technically totally valid shapes.

Permalink Reply by Arie-Willem de Jongh on February 20, 2013 at 4:03pm