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IDProjectCategoryView StatusDate SubmittedLast Update
0030234Community[OCCT] OCCT:Meshpublic2018-10-11 13:392018-10-16 14:14
Assigned Tooan 
PlatformWindowsOSVC++ 2015OS Version64 bit
Product Version[OCCT] 7.3.0 
Target VersionFixed in Version 
Summary0030234: BRepMesh_IncrementalMesh fail to discretize some zero-length free edges
- enable Standard_ConstructionError exceptions in config
- set the BRepMesh_IncrementalMesh to use relative deflection
- try to mesh a shape with at least a zero-length free edge (for instance an edge with a 0-radius circle, as it can be found in the outer wire of a sphere)

Then a Standard_ConstructionError exception will be raised inside BRepMesh_IncrementalMesh::discretizeFreeEdges() > CPnts_TangentialDeflection::CPnts_TangentialDeflection() > GCPnts_TangentialDeflection::Initialize()

In my test, with a empty circle for instance, the computed deflection for this edge is less than Precision::Confusion(), which explains the exception.

one possible fix would be to modify BRepMesh_ShapeTool::RelativeEdgeDeflection to have a minimum value strictly greater than Precison::Confusion()
Steps To Reproducerestore empty_circle.brep a
incmesh a 0.005 -relative
TagsNo tags attached.
Test case number
Attached Files? file icon empty_circle.brep (304 bytes) 2018-10-11 15:21

- Relationships

-  Notes
oan (developer)
2018-10-11 14:24

Dear adrien_schvalberg_technodigit,

please attach BREP model with described behaviour.
adrien_schvalberg_technodigit (reporter)
2018-10-11 15:23

load the brep (a 0-radius circle at origin),
test discretization with
BRepMesh_IncrementalMesh mesher(theEdge, 0.005, Standard_True);
oan (developer)
2018-10-11 18:00

Thanks a lot for the use case.
Seems the problem is not reproduced using patch #26106.
However, it has not been integrated to master yet.
adrien_schvalberg_technodigit (reporter)
2018-10-11 18:09

Thanks for the update.

to be sure: as I already reported it, you must have an OCC config with Standard_ConstructionError exceptions enabled (ie with #if !defined No_Exception && !defined No_Standard_ConstructionError directive evaluating to true) to reproduce the problem
oan (developer)
2018-10-11 18:24

Great notice - I had different configs for master build and patch.

So, unfortunately, it does not solve the problem(
We will investigate it.

Thanks for the details!
adrien_schvalberg_technodigit (reporter)
2018-10-16 10:19

I think I'm mistakenly assigned to this issue. I didn't notice since when...

- Issue History
Date Modified Username Field Change
2018-10-11 13:39 adrien_schvalberg_technodigit New Issue
2018-10-11 13:39 adrien_schvalberg_technodigit Assigned To => oan
2018-10-11 14:24 oan Note Added: 0079889
2018-10-11 14:29 oan Assigned To oan => adrien_schvalberg_technodigit
2018-10-11 14:29 oan Status new => feedback
2018-10-11 15:21 adrien_schvalberg_technodigit File Added: empty_circle.brep
2018-10-11 15:23 adrien_schvalberg_technodigit Note Added: 0079894
2018-10-11 17:59 oan Relationship added related to 0026106
2018-10-11 18:00 oan Note Added: 0079906
2018-10-11 18:03 oan Steps to Reproduce Updated View Revisions
2018-10-11 18:09 adrien_schvalberg_technodigit Note Added: 0079907
2018-10-11 18:19 oan Relationship deleted related to 0026106
2018-10-11 18:24 oan Note Added: 0079908
2018-10-16 10:19 adrien_schvalberg_technodigit Note Added: 0079997
2018-10-16 14:14 oan Assigned To adrien_schvalberg_technodigit => oan
2018-10-16 14:14 oan Status feedback => assigned

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