BrepFaceList.SplitKinkyFaces() not creating subfaces

Rhino Developer
1

Hi there,
I am trying to subdivide a brep that is to “smooth” for other software. My aim is to split the brep at the kinky faces.

I am trying this:

obj = rs.GetObject()
brep = rs.coercebrep(obj)

brep.Faces.SplitKinkyFaces()

for f in brep.Faces:
    sc.doc.Objects.AddBrep(f.ToBrep(), Rhino.DocObjects.ObjectAttributes(), None, False, True)

which only adds the isocurves in the brep.

image
image1090×621 49 KB

Am I misunderstanding the method or what am I missing?

Thanks,
T.

2

Can you post the input geometry? This helps in pinpointing the problem.

3

@menno, here you go. :slight_smile:

TestSplitKinkyFaces.3dm (68.8 KB)

The crossed out lines would of course not have to be split, but I guess you have assumed this anyways.

image
image924×509 43.1 KB

4

The left surface has “Isocurve Density” set to -1 because the “Show surface isocurve” is switched off (see Properties panel). If you switch it on, the surfaces look exactly the same.

Neither surface has a kinky face. You can also test this using DivideAlongCreases SplitAtTangents=No SplitAtKinks=Yes without any Python code. If you were to have a surface with a crease, a.k.a. kink, it would split. A kink is a mathematical thing where knot values in the surface definition repeat, causing the control point to always lie directly on the surface.

image
image1013×415 8.35 KB

5

Also, it looks like DivideAlongCreases only works if there is a true crease. If there is a fully-multiple knot but the control points are aligned such that there is higher than G0-continuity, it won’t split.

6

@menno
Gotcha.
Once I replace brep.Faces.SplitKinkyFaces() with brep.Faces.SplitFacesAtTangents() it works perfectly.

Thanks!

1 Like