FaceBinder: What is meant by the Sew property?

[Roy_043]

I do not understand what is meant by the Sew property of a FaceBinder. Changing it seems to have no effect?

[wmayer]

If there are e.g. two faces inside a compound that visually share an edge then in the topology there are still two edges. The sew operation changes the topology to share sub-shapes where needed. The operation may also result in changing the shape type.

Example code:

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import FreeCAD
import Part

f1=Part.makePlane(10,10,FreeCAD.Vector(0,0,0))
f2=Part.makePlane(10,10,FreeCAD.Vector(10,0,0))
shape=Part.Compound([f1,f2])
shape.ShapeType
#Compound
len(shape.Edges)
#8

shape.sewShape()
shape.ShapeType
#Shell
len(shape.Edges)
#7

[Roy_043]

Thanks for your explanation. I think I understand on a theoretical level, but would there be a FaceBinder example where this would have a visible effect?

[NormandC]

Example code:

Being an absolute neophyte at Python, I can't get this to work. I tried adding

Code: Select all

from FreeCAD import Part
from FreeCAD import Base

I still get errors that FreeCAD.Part has no attribute 'makePlane' nor 'Compound'.

Edit: nevermind, I loaded the Part workbench and this fixed it.

[wmayer]

I fixed the code to explicitly import Part.

[arnn]

Thanks for your explanation. I think I understand on a theoretical level, but would there be a FaceBinder example where this would have a visible effect?

Trying to understand the Sew & Remove Splitter, Do you have more links/understanding on this.
Many thanks.

[Roy_043]

Sew:
I still do not understand 'Sew'. A facebinder is already a shell by default, and not a compound, it seems:

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>>> fb = App.ActiveDocument.Facebinder
>>> fb.Shape.ShapeType
'Shell'

Remove Splitter:
In the attached example faces from two stacked boxes were used as the source for two facebinders. The FB on the right has 'Remove Splitter' set to 'True'.