merge faces (again)

[Cyril]

Hi,

I found many related topic but I cannot find the right way merges faces. My cases are simple. I would like to merge faces with a common edge (partial or full).


Unsuccessful try
I found this old topic : face union. I made some tries using removeSplitter but no success :

Code: Select all

>>> cp = Part.Compound([doc.Face.Shape, doc.Face001.Shape])
>>> cp.removeSplitter()
<Shape object at 0x7fe3f8029580>
>>> result = cp.removeSplitter()
>>> result.Faces
[<Face object at 0x555e3c9484e0>, <Face object at 0x555e3c9cf8d0>]

Successful try but not allways merged
s1 and s2 are faces to merge

Code: Select all

>>> Part.ShapeUpgrade.UnifySameDomain(s1.fuse(s2))
<ShapeUpgrade_UnifySameDomain object>
>>> u = Part.ShapeUpgrade.UnifySameDomain(s1.fuse(s2))
>>> u.shape().Faces
[<Face object at 0x56418661fdb0>, <Face object at 0x564185fbb7c0>]
>>> u.build()
>>> u.shape().Faces
[<Face object at 0x5641826eab40>]
>>> s1.Area + s2.Area
357068.22801917716
>>> u.shape().Faces
[<Face object at 0x564186588430>]
>>> s3 = u.shape().Faces[0]
>>> s3.Area
357068.22801917745

Unfortunately I did not manage to make it always work yet. Also I don't understand all on this tool options.

Please help

Edits :

• Using shape.sewShape() before using UnifySameDomain help.
• Faces needs to be perfectly coplanar if you expect UnifySameDomain to build a single face from two or more faces.
• Found related commit which is from this october.
• Found more information in OCCT reference manual
• SetLinearTolerance seems to have no effect. eg. if 2 faces have a 1 cm gap between them. Using SetLinearTolerance(10) or even 100 do not merge faces.

OS: Manjaro Linux (GNOME/gnome-xorg)
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.23211 (Git)
Build type: Release
Branch: master
Hash: caf30cd7ce14ebb06f11aa045e9f86ac284fa10a
Python version: 3.8.6
Qt version: 5.15.2
Coin version: 4.0.1
OCC version: 7.5.0
Locale: French/Switzerland (fr_CH)

[openBrain]

Did you try

Code: Select all

s1.fuse(s2)

[Cyril]

Did you try

Code: Select all

s1.fuse(s2)

Yes. As describe above in the UnifySameDomain process. According to my observations fuse only create a container shape (shell, compound or else) containing fused shapes but do not actually merge 2 shapes into 1.

[mario52]

hi

like this ?

mergeFacesAgain.FCStd

(9.7 KiB) Downloaded 71 times

Code: Select all

import Part
comP = []
selectionObjects = FreeCADGui.Selection.getSelection()

for i in selectionObjects:
    comP.append(i.Shape)

comp = Part.makeCompound(comP)
Part.show(comp)

mario

[Cyril]

hi

like this ?

mario

Thanks for suggesting but as I said. Compound is just a container. It does not merge 2 faces into 1 face. Goal is to start with 2 Part.Face and to end with 1 Part.Face (sum of areas). Why ? To simplify geometry as much as possible.

[kisolre]

Not a script but I tried drawing two touching triangles in Draft, selecting both and upgrading, applying Part/create a copy/refine shape on the result and that removed the seam. Maybe this can help?

[mario52]

hi

Goal is to start with 2 Part.Face and to end with 1 Part.Face (sum of areas). Why ? To simplify geometry as much as possible.

ok
maybe with OpenSCAD2Dgeom

Code: Select all

def subtractfaces(faces):
def fusefaces(faces):
def subtractfaces2(faces):

mario

[Cyril]

Not a script but I tried drawing two touching triangles in Draft, selecting both and upgrading, applying Part/create a copy/refine shape on the result and that removed the seam. Maybe this can help?

Interesting. I don't understand how it does this in source code yet but yes resulting shape contain only 1 face. It seems to run removeSplitter

Also I found out that executing upgrade twice (without using Part …) also join faces. A fixed bug report is talking about this. I found used function called joinFaces in Draft source code. They do it in a way I did not expect. I will compare this method with UnifySameDomain to see if one is giving better results.

maybe with OpenSCAD2Dgeom

Code: Select all

def subtractfaces(faces):
def fusefaces(faces):
def subtractfaces2(faces):

fusefaces return 2 faces (3 if they are overlapping). Other doesn't join faces neither.
I also tried OpenSCAD2Dgeom.Overlappingfaces which looked promising but did not get any good result.