View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0030336 | Community | OCCT:Data Exchange | public | 2018-11-02 17:48 | 2018-11-02 17:48 |
| Reporter | ventu | Assigned To | |||
| Priority | normal | Severity | major | ||
| Status | new | Resolution | open | ||
| Product Version | 7.3.0 | ||||
| Summary | 0030336: Missing surfaces when importing STeP file due to wrong NURBS surface continuity detection | ||||
| Description | This problem is very similar to 0029345. The attached is imported with several surfaces missing. The reason is: _ some NURBS surface has multiple internal knots, so it is marked as GeomAbs_C0 without any check on whether this is really the case; _ then an offset is made which refuses to work on C0 surfaces; _ so the face is discarded. Those surfaces are not really C0, but no check is made to see if the derivatives are continuous at the knots with mutiplicity=degree. | ||||
| Additional information and documentation updates | Below is some code which, added at the end of Geom_BSplineSurface::Geom_BSplineSurface, fixes this particular case. Notice I don't deem it as production ready, since it uses fixed arbitrary tolerances and I don't know if it can have any side effect. if (Usmooth==GeomAbs_C0) { GeomAbs_Shape OldVsmooth=Vsmooth; Vsmooth=GeomAbs_C1; bool Continue=true; try { for (Standard_Integer i=2;i<NbUKnots()&&Continue;++i) if (UMultiplicity(i)>=udeg) { Standard_Real t=UKnot(i),delta=.00001,t1,t2; while (true) { t1=t-delta; t2=t+delta; if (t1<t&&t2>t) break; delta*=10.; } for (Standard_Integer j=1;j<=NbVKnots()&&Continue;++j) { Standard_Real k=VKnot(j); gp_Pnt P; gp_Vec D1Ul,D1Ur,D1V; D1(t1,k,P,D1Ul,D1V); D1(t2,k,P,D1Ur,D1V); Standard_Real Angle=D1Ul.Angle(D1Ur); if (Angle>M_PI/360) //Tolleranza di mezzo grado (arbitraria) Continue=false; } } } catch (...) {Continue=false;} Vsmooth=OldVsmooth; if (Continue) Usmooth=GeomAbs_C1; } if (Vsmooth==GeomAbs_C0) { GeomAbs_Shape OldUsmooth=Usmooth; Usmooth=GeomAbs_C1; bool Continue=true; try { for (Standard_Integer i=2;i<NbVKnots()&&Continue;++i) if (VMultiplicity(i)>=vdeg) { Standard_Real t=VKnot(i),delta=.00001,t1,t2; while (true) { t1=t-delta; t2=t+delta; if (t1<t&&t2>t) break; delta*=10.; } for (Standard_Integer j=1;j<=NbUKnots()&&Continue;++j) { Standard_Real k=UKnot(j); gp_Pnt P; gp_Vec D1U,D1Vl,D1Vr; D1(k,t1,P,D1U,D1Vl); D1(k,t2,P,D1U,D1Vr); Standard_Real Angle=D1Vl.Angle(D1Vr); if (Angle>M_PI/360) //Tolleranza di mezzo grado (arbitraria) Continue=false; } } } catch (...) {Continue=false;} Usmooth=OldUsmooth; if (Continue) Vsmooth=GeomAbs_C1; } | ||||
| Tags | No tags attached. | ||||
| Test case number | |||||
