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0030454Community[OCCT] OCCT:Modeling Algorithmspublic2019-01-22 21:012019-12-17 13:50
[OCCT] 7.3.0 
0030454: Modeling Algorithms - BRepBuilderAPI_Sewing fails after BRepAlgoAPI_Fuse
In previsous versions of OCCT (e.g. 6.8), calling BRepAlgoAPI_Fuse with faces and shells resulted in a shape that was a single shell. However, with OCCT 7.3 BRepAlgoAPI_Fuse returns a shape with multiple faces/shells. To achieve the old behavior we have tried to follow BRepAlgoAPI_Fuse with BRepBuilderAPI_Sewing. This generally works, but the attached example returns 2 shells from the sew operation when we expect to get 1 shell. I have a 2 questions:

1) Is there a better option to get the old behavior of BRepAlgoAPI_Fuse to return a single shell without using sewing?

2) I believe BRepBuilderAPI_Sewing should return a single shell with the attached example.
Compile and run the example in the attached tar file.
No tags attached.
tgz Fuse_Shell.tgz (7,794) 2019-01-22 21:01
tgz Fuse_Shell2.tgz (31,810) 2019-01-23 19:12
Issue History
2019-01-22 21:01galbramcNew Issue
2019-01-22 21:01galbramcAssigned To => msv
2019-01-22 21:01galbramcFile Added: Fuse_Shell.tgz
2019-01-23 17:44galbramcNote Added: 0081868
2019-01-23 19:12galbramcFile Added: Fuse_Shell2.tgz
2019-01-23 19:13galbramcNote Added: 0081869
2019-10-11 22:31galbramcAssigned Tomsv => abv
2019-10-11 22:31galbramcNote Added: 0088057
2019-12-17 13:50kgvSummaryBRepBuilderAPI_Sewing fails after BRepAlgoAPI_Fuse => Modeling Algorithms - BRepBuilderAPI_Sewing fails after BRepAlgoAPI_Fuse

2019-01-23 17:44   
Update. I just noticed if I sew the result from sew one more time I get the single shell I'm looking for.
2019-01-23 19:13   
I've attached a 2nd case (Fuse_Shell2.tgz) where repeating the sew operation does not work.

In summary. The files src.brep and tool.brep give the expected result if sew is called twice. sec2.brep and tool2.brep do not give a single shell even after calling sew twice.
2019-10-11 22:31   
I just wanted to confirm that I still see this issue in OCCT 7.4. Any guidance on how I'm possibly using these functions incorrectly would be greatly appreciated.