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IDProjectCategoryView StatusDate SubmittedLast Update
0030160Open CASCADE[OCCT] OCCT:Modeling Algorithmspublic2018-09-25 11:102020-08-28 13:25
Assigned Toemv 
PlatformOSOS Version
Product Version 
Target Version[OCCT] 7.6.0*Fixed in Version 
Summary0030160: DBRep_IsoBuilder builds wrong isolines for planar faces
DescriptionDBRep_IsoBuilder builds wrong isolines for planar faces. Two planar faces are covers of the pipe, they are bounded by closed BSpline curves.
Steps To Reproducerestore [locate_data_file OCC1477_bsplinewire_c0.brep] sp
restore [locate_data_file OCC1477_profile1_circle.brep] pr
wire pr pr

mksweep sp
addsweep pr -T -R
buildsweep result -R -S

explode result f
isos result_4 50
isos result_5 50
donly result_4 result_5
TagsNo tags attached.
Test case number
Attached Files

- Relationships
related to 0031688closedbugmaster Visualization - Wrong ISO lines for a face created from BSpline 

-  Notes
emv (developer)
2018-09-25 16:39
edited on: 2018-09-26 09:28

The problem comes from the incorrect classification of the point (through Geom2dHatch_Classifier) relatively the face. The classification is incorrect due to incorrect intersection of two 2d curves - classification ray intersects the pcurve of the face. In this intersection one intersection point is missing.

Here is the draw script to reproduce the problem with 2d intersection:
pcurve result_4
dump result_4_1

line ray 0.0 -16.288656886901943 -0.13150161507367475 0.99131595630909475
trim ray ray 0.0 15.299078275810480

2dintersect ray result_4_1 -tol 1.e-9
# only one intersection point

Note, that saving the ray, restoring it and making intersection with restored one will lead to two intersection points. So, it looks like the problem is connected to floating point precision instability.
It has to be investigated further.

- Issue History
Date Modified Username Field Change
2018-09-25 11:10 jgv New Issue
2018-09-25 11:10 jgv Assigned To => msv
2018-09-25 11:44 msv Assigned To msv => emv
2018-09-25 11:44 msv Status new => assigned
2018-09-25 16:39 emv Note Added: 0079398
2018-09-26 09:13 emv Note Edited: 0079398 View Revisions
2018-09-26 09:28 emv Note Edited: 0079398 View Revisions
2019-08-12 17:59 emv Target Version 7.4.0 => 7.5.0
2020-07-24 18:04 kgv Relationship added related to 0031688
2020-08-28 13:25 emv Target Version 7.5.0 => 7.6.0*

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