0030160: DBRep_IsoBuilder builds wrong isolines for planar faces - MantisBT

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ID

Project

Category

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Date Submitted

Last Update

0030160

Open CASCADE

[OCCT] OCCT:Modeling Algorithms

public

2018-09-25 11:10

2018-09-26 09:28

Reporter

jgv

Assigned To

emv

Priority

normal

Severity

minor

Status

assigned

Resolution

open

Platform

OS

OS Version

Product Version

Target Version

[OCCT] 7.4.0*

Fixed in Version

Summary

0030160: DBRep_IsoBuilder builds wrong isolines for planar faces

Description

DBRep_IsoBuilder builds wrong isolines for planar faces. Two planar faces are covers of the pipe, they are bounded by closed BSpline curves.

Steps To Reproduce

restore [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
fit

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Notes
(0079398) 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

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