View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0031430 | Community | OCCT:Modeling Data | public | 2020-03-14 13:33 | 2020-12-02 17:12 |
| Reporter | Roman Lygin | Assigned To | bugmaster | ||
| Priority | normal | Severity | crash | ||
| Status | closed | Resolution | fixed | ||
| Target Version | 7.5.0 | Fixed in Version | 7.5.0 | ||
| Summary | 0031430: Modeling Data - Offset surfaces on C1 surfaces (with multiplicity equal to degree) may still throw exception | ||||
| Description | Valid offset surfaces created on C1-continuous basis surface (e.g. B-Spline) but with knot multiplicity equal to degree may cause an exception later on. One of the scenarios is from inside Shape Healing, when Geom_RectangularTrimmedSurface on such offset will call a ctor of Geom_OffsetSurface with the parameter of enforced continuity check (which is a default value of the parameter). The check in G_OS ctor is based on knot multiplicity, not on real geometrical continuity. Several approaches are possible: a. enforce skipped continuity check in G_RTS ctor (as G_OS already existed by that time and thus is valid) b. change checking algorithm to really verify C1/G1 continuity (not just knot multiplicity) and allow creation of OS. In this case the parameter can be removed at all. c. change default value of parameter of continuity check in G_OS to skip the check and thus allow creation of offset on any surface. I would recommend b or at least c, whereas a is just a bare minimum. | ||||
| Steps To Reproduce | restore shape.brep s fixshape r s | ||||
| Tags | No tags attached. | ||||
| Test case number | bugs/modalg_7/bug31430 | ||||
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shape.7z (8,894 bytes) |
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Branch CR31430 has been created by Roman Lygin. SHA-1: 69bc8943bdfffc43d78411a1d670195f209fe8a7 Detailed log of new commits: Author: Roman Lygin Date: Sat Mar 14 13:49:17 2020 +0300 0031430: Offset surfaces on C1 surfaces (with multiplicity equal to degree) may still throw exception |
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The simplest fix for the approach 'a' has been provided. Options b and c remain at OCC team discretion. |
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Branch CR31430 has been updated forcibly by msv. SHA-1: 6055af5077808287fbca9e2052f24dde6aad5df1 |
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Branch CR31430 has been updated forcibly by msv. SHA-1: a3b365ce2d39befb731c281844867996e659f5ea |
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Please review. http://jenkins-test-12.nnov.opencascade.com/view/CR31430-master-MSV/view/COMPARE/ |
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It is not needed to integrate this fix because we have solution b. implemented yet. The Roman's statement " The check in G_OS ctor is based on knot multiplicity, not on real geometrical continuity. " is wrong. Continuity check includes checking real geometry continuity. |
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Indeed, according to the actual code, the solution b) is implemented. The check is done with Precision::Angular(). May be the surface in the attached shape does not follow this condition, and the divergence of normals at knots exceeds the angular precision. So, I am not sure if we can accept this patch with skipped check for C0. |
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The original surface comes from Parasolid where angular precision is likely 1e-11 (not 1e-12 as in OCC). Here is the workflow: 1. Create Geom_OffsetSurface on original basis surface (flag isnotC0Check = true). 2. Create face on this G_OS 3. Feed into Shape Healing. 4. Crash in FixMissingSeam which creates G_OS on top of G_RTS on top of original basis surface. When G_OS is created on G_RTS it uses isNotC0Check with default value which is false. So the point is that OCC cannot create G_OS on top of the same basis surface it once considered acceptable for creating G_OS. The fix is to stress the point - if the basis surface was once considered OK for G_OS then such a surface must remain valid inside OCC and must not be refused anywhere inside it. |
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Roman, if offset surface is based on trimmed one, continuity check is performed for trimmed domain and surface can be valid. If we change trim, surface can become invalid. |
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Igor, see the key point in explanation - if the surface is once valid for offset inside OCC it must remain valid inside it. BTW, it's an opposite case here - the original B-Spline surface was once valid and then trimmed and then G_OS refused to accept it. |
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Branch CR31430 has been updated forcibly by msv. SHA-1: 75a61baa9f129124e5556871d6cdd5c339dad689 |
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OK, we accept the fix with a) solution. I have updated the commit message with the reason. |
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For integration: occt - CR31430 products - none. |
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Thanks Mikhail! |
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Branch CR31430 has been deleted by inv. SHA-1: 75a61baa9f129124e5556871d6cdd5c339dad689 |
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Combination - OCCT branch : IR-2020-03-20 master SHA - 7ef1f9b7c1d9301c158a593dc5facb5a33450318 fe4497f3246e6bc1ced97ac331c148f0809ded15 Products branch : IR-2020-03-20 SHA - f10b867b449ebfa55e0a3c8cb276ae511f9cf7f2 was compiled on Linux, MacOS and Windows platforms and tested in optimize mode. Number of compiler warnings: No new/fixed warnings Regressions/Differences/Improvements: No regressions/differences CPU differences: Debian80-64: OCCT Total CPU difference: 16845.960000000137 / 16685.300000000094 [+0.96%] Products Total CPU difference: 11305.960000000074 / 11298.700000000106 [+0.06%] Windows-64-VC14: OCCT Total CPU difference: 18268.609375 / 18088.765625 [+0.99%] Products Total CPU difference: 13110.078125 / 13084.390625 [+0.20%] Image differences : No differences that require special attention Memory differences : No differences that require special attention |
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occt: master fb991777 2020-03-14 10:49:17 Committer: bugmaster Details Diff |
0031430: Offset surfaces on C1 surfaces (with multiplicity equal to degree) may still throw exception In constructor of Geom_RectangularTrimmedSurface, skip check if an offset surface has insufficient continuity. The reason is that this surface has already passed the check once created. So, here we must not apply more strict check than that first time. |
Affected Issues 0031430 |
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| mod - src/Geom/Geom_RectangularTrimmedSurface.cxx | Diff File | ||
| add - tests/bugs/modalg_7/bug31430 | Diff File | ||
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2020-03-14 13:33 | Roman Lygin | New Issue | |
| 2020-03-14 13:33 | Roman Lygin | Assigned To | => msv |
| 2020-03-14 13:33 | Roman Lygin | File Added: shape.7z | |
| 2020-03-14 13:34 | Roman Lygin | Relationship added | related to 0025124 |
| 2020-03-14 13:35 | Roman Lygin | Summary | Offset surfaces on C1 surfaces => Offset surfaces on C1 surfaces (with multiplicity equal to degree) may still throw exception |
| 2020-03-14 13:53 | git | Note Added: 0090942 | |
| 2020-03-14 13:54 | Roman Lygin | Note Added: 0090943 | |
| 2020-03-14 13:54 | Roman Lygin | Status | new => resolved |
| 2020-03-14 20:20 | kgv | Summary | Offset surfaces on C1 surfaces (with multiplicity equal to degree) may still throw exception => Modeling Data - Offset surfaces on C1 surfaces (with multiplicity equal to degree) may still throw exception |
| 2020-03-16 11:31 | git | Note Added: 0090955 | |
| 2020-03-16 11:33 | git | Note Added: 0090956 | |
| 2020-03-16 11:34 |
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Assigned To | msv => abv |
| 2020-03-16 11:35 |
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Note Added: 0090957 | |
| 2020-03-16 12:30 |
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Note Added: 0090961 | |
| 2020-03-16 12:30 |
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Assigned To | abv => msv |
| 2020-03-16 12:30 |
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Status | resolved => feedback |
| 2020-03-16 12:52 |
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Note Added: 0090962 | |
| 2020-03-16 12:52 |
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Assigned To | msv => Roman Lygin |
| 2020-03-16 13:23 | Roman Lygin | Assigned To | Roman Lygin => msv |
| 2020-03-16 13:28 | Roman Lygin | Note Added: 0090965 | |
| 2020-03-16 13:41 |
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Note Added: 0090966 | |
| 2020-03-16 13:46 | Roman Lygin | Note Added: 0090967 | |
| 2020-03-18 09:52 | git | Note Added: 0091001 | |
| 2020-03-18 09:53 |
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Note Added: 0091002 | |
| 2020-03-18 09:56 |
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Note Added: 0091003 | |
| 2020-03-18 09:56 |
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Assigned To | msv => bugmaster |
| 2020-03-18 09:56 |
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Status | feedback => reviewed |
| 2020-03-18 10:08 |
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Relationship added | related to 0031436 |
| 2020-03-18 11:10 | Roman Lygin | Note Added: 0091010 | |
| 2020-03-19 16:31 | bugmaster | Changeset attached | => occt master fb991777 |
| 2020-03-19 16:31 | bugmaster | Status | reviewed => verified |
| 2020-03-19 16:31 | bugmaster | Resolution | open => fixed |
| 2020-03-22 11:31 | git | Note Added: 0091125 | |
| 2020-03-22 11:41 | bugmaster | Note Added: 0091159 | |
| 2020-03-22 11:44 | bugmaster | Test case number | => bugs/modalg_7/bug31430 |
| 2020-12-02 16:43 |
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Fixed in Version | => 7.5.0 |
| 2020-12-02 17:12 |
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Status | verified => closed |
