0031301: Data Exchange - Export to STEP corrupts the shape

For small edges fully covered by tolerances of vertices BSpline periodic curves are converted to not periodic BSpline curves by cutting segment before writing.
In the class TopoDSToStep_MakeStepEdge permute of edge vertices for closed curves was added for the case when the range obtained from the vertex projection contradicts the edge range in order to avoid computation of the invalid edge range after reading.

src/GeomToStep/GeomToStep_MakeCurve.cxx

@@ -42,6 +42,7 @@
 #include <StepGeom_Conic.hxx>
 #include <StepGeom_Curve.hxx>
 #include <StepGeom_Line.hxx>
+#include <Geom2d_TrimmedCurve.hxx>
 
 //=============================================================================
 // Creation d' une Curve de prostep a partir d' une Curve de Geom
@@ -162,6 +163,10 @@ GeomToStep_MakeCurve::GeomToStep_MakeCurve ( const Handle(Geom2d_Curve)& C)
     GeomToStep_MakeBoundedCurve MkBoundedC(L);
     theCurve = MkBoundedC.Value();
   }
+  else if (C->IsKind(STANDARD_TYPE(Geom2d_TrimmedCurve))) {
+    GeomToStep_MakeCurve aMaker = (Handle(Geom2d_TrimmedCurve)::DownCast(C)->BasisCurve());
+    theCurve = aMaker.Value();
+  }
   else
     done = Standard_False;
 } 

src/TopoDSToStep/TopoDSToStep_MakeStepEdge.cxx

@@ -53,6 +53,8 @@
 #include <Transfer_FinderProcess.hxx>
 #include <TransferBRep.hxx>
 #include <TransferBRep_ShapeMapper.hxx>
+#include <BRepTools.hxx>
+#include <ShapeAnalysis_Curve.hxx>
 
 // Processing of non-manifold topology (ssv; 11.11.2010)
 // ----------------------------------------------------------------------------
@@ -185,6 +187,55 @@ void TopoDSToStep_MakeStepEdge::Init(const TopoDS_Edge& aEdge,
   Handle(Geom_Curve) C = CA.Curve().Curve();
   if (!C.IsNull()) {
     C = Handle(Geom_Curve)::DownCast(C->Copy());
+   
+    if (C->IsPeriodic())
+    {
+      Standard_Real dpar = CA.LastParameter() - CA.FirstParameter();
+
+      Standard_Real aTolV1 = BRep_Tool::Tolerance(Vfirst);
+      Standard_Real aTolV2 = BRep_Tool::Tolerance(Vlast);
+      gp_Pnt aP1 = BRep_Tool::Pnt(Vfirst);
+      gp_Pnt aP2 = BRep_Tool::Pnt(Vlast);
+      gp_Pnt  pproj;
+      gp_Pnt aP11 = CA.Value(CA.FirstParameter());
+      gp_Pnt aP12 =CA.Value(CA.LastParameter());
+      ShapeAnalysis_Curve sac;
+      sac.Project (C, aP1, Tolerance(), pproj, U1, Standard_False);
+      sac.Project (C, aP2, Tolerance(), pproj, U2, Standard_False);
+      Standard_Real dU = U2 - U1;
+
+      if (dpar <= 0)
+        dpar += (ceil(fabs(dpar) / C->Period()) *C->Period());
+
+      if (dU <= 0)
+        dU += (ceil(fabs(dU) / C->Period()) *C->Period());
+      // if range obtained from projection of vertices is contradicted with range of the edge
+       //tnen vertices should be permuted
+
+      if ((dU  > Precision::PConfusion() &&  dU <= 0.1 * C->Period() && dpar > 0.5 * C->Period()) ||
+        (dpar  > Precision::PConfusion() && dpar <= 0.1 * C->Period() && dU > 0.5 * C->Period()))
+      {
+        Handle(StepShape_Vertex) aVtemp = V1; 
+        V1 = V2; V2 = aVtemp;
+      }
+
+      gp_Pnt aPm = CA.Value((CA.FirstParameter() + CA.LastParameter()) *0.5);
+      Standard_Real aDist11 = aP11.Distance(aP12);
+      Standard_Real aDist1m = aP11.Distance(aPm);
+      Standard_Real aDist2m = aP12.Distance(aPm);
+      Standard_Real aDistMax = Max(Max(aDist1m, aDist2m), aDist11);
+      Standard_Boolean isSmallCurve = (aDistMax <= aTolV1 ||  aDistMax <= aTolV2);
+      //for small edge lying BSpline periodic curve segment of the BSpline periodic curve is used to avoid invalid computation of the edge range duriring reading 
+      if (BRepTools::Compare(Vfirst, Vlast) && isSmallCurve  && C->IsPeriodic() && dpar > Precision::PConfusion() && dpar <= 0.1 * C->Period())
+      {
+        if (C->IsKind(STANDARD_TYPE(Geom_BSplineCurve)))
+        {
+          Handle(Geom_BSplineCurve) aBspl1 = Handle(Geom_BSplineCurve)::DownCast(C->Copy());
+          aBspl1->Segment (CA.FirstParameter(), CA.LastParameter());
+          C =  aBspl1;
+        }
+      }
+    }
     gp_Trsf Tr1 = CA.Trsf();
     C->Transform(Tr1);
     GeomToStep_MakeCurve MkCurve(C);

tests/bugs/step/bug31301

@@ -0,0 +1,5 @@
+testreadstep [locate_data_file bug31301.stp] s
+testwritestep bug31301_1.stp s
+testreadstep bug31301_1.stp s1
+checkshape s1 f
+checkmaxtol s1 -ref 0.0078

tests/de/step_1/G1

@@ -1,17 +1,16 @@
 # !!!! This file is generated automatically, do not edit manually! See end script
 puts "TODO CR23096 ALL: CHECKSHAPE : Faulty" 
-puts "TODO CR23096 ALL: TOLERANCE : Faulty" 
 
 
 set filename trj7_pm5-ug-214.stp
 
 set ref_data {
 DATA        : Faulties = 0  ( 0 )  Warnings = 0  ( 0 )  Summary  = 0  ( 0 )
-TPSTAT      : Faulties = 0  ( 0 )  Warnings = 5  ( 184 )  Summary  = 5  ( 184 )
+TPSTAT      : Faulties = 0  ( 0 )  Warnings = 3  ( 184 )  Summary  = 3  ( 184 )
-CHECKSHAPE  : Wires    = 2  ( 0 )  Faces    = 2  ( 0 )  Shells   = 0  ( 0 )   Solids   = 0 ( 0 )
+CHECKSHAPE  : Wires    = 1  ( 0 )  Faces    = 1  ( 0 )  Shells   = 0  ( 0 )   Solids   = 0 ( 0 )
 NBSHAPES    : Solid    = 1  ( 1 )  Shell    = 1  ( 1 )  Face     = 236  ( 236 ) 
 STATSHAPE   : Solid    = 1  ( 1 )  Shell    = 1  ( 1 )  Face     = 236  ( 236 )   FreeWire = 0  ( 0 ) 
-TOLERANCE   : MaxTol   =   0.9036712735  (  0.01854047103 )  AvgTol   =  0.002850040066  (  0.0006030086632 )
+TOLERANCE   : MaxTol   = 0.004380869792  (  0.01854047103 )  AvgTol   =  0.000165684279  (  0.0006030086632 )
 LABELS      : N0Labels = 1  ( 1 )  N1Labels = 34  ( 34 )  N2Labels = 0  ( 0 )   TotalLabels = 35  ( 35 )   NameLabels = 1  ( 1 )   ColorLabels = 35  ( 35 )   LayerLabels = 1  ( 1 )
 PROPS       : Centroid = 0  ( 0 )  Volume   = 0  ( 0 )  Area     = 0  ( 0 )
 NCOLORS     : NColors  = 11  ( 11 )

tests/de/step_4/D9

@@ -6,11 +6,11 @@ set filename test-m020306-v1.stp
 
 set ref_data {
 DATA        : Faulties = 0  ( 0 )  Warnings = 0  ( 0 )  Summary  = 0  ( 0 )
-TPSTAT      : Faulties = 0  ( 0 )  Warnings = 153  ( 114 )  Summary  = 153  ( 114 )
+TPSTAT      : Faulties = 1  ( 0 )  Warnings = 153  ( 114 )  Summary  = 154  ( 114 )
 CHECKSHAPE  : Wires    = 0  ( 0 )  Faces    = 0  ( 0 )  Shells   = 0  ( 0 )   Solids   = 0 ( 0 )
 NBSHAPES    : Solid    = 1  ( 1 )  Shell    = 1  ( 1 )  Face     = 742  ( 742 ) 
 STATSHAPE   : Solid    = 1  ( 1 )  Shell    = 1  ( 1 )  Face     = 742  ( 742 )   FreeWire = 0  ( 0 ) 
-TOLERANCE   : MaxTol   = 0.008481946718  (  0.01167623167 )  AvgTol   =  0.000132472064  (  0.0003097606769 )
+TOLERANCE   : MaxTol   = 0.008481946718  (  0.01167623167 )  AvgTol   =  0.0001322682241  (  0.0003097606769 )
 LABELS      : N0Labels = 1  ( 1 )  N1Labels = 0  ( 0 )  N2Labels = 0  ( 0 )   TotalLabels = 1  ( 1 )   NameLabels = 1  ( 1 )   ColorLabels = 0  ( 0 )   LayerLabels = 0  ( 0 )
 PROPS       : Centroid = 0  ( 0 )  Volume   = 0  ( 0 )  Area     = 0  ( 0 )
 NCOLORS     : NColors  = 0  ( 0 )

tests/de/step_4/E1

@@ -1,13 +1,16 @@
 # !!!! This file is generated automatically, do not edit manually! See end script
+puts "TODO CR23096 ALL: TPSTAT : Faulty" 
+
+
 set filename test-m020306-v2.stp
 
 set ref_data {
 DATA        : Faulties = 0  ( 0 )  Warnings = 0  ( 0 )  Summary  = 0  ( 0 )
-TPSTAT      : Faulties = 0  ( 0 )  Warnings = 61  ( 157 )  Summary  = 61  ( 157 )
+TPSTAT      : Faulties = 1  ( 0 )  Warnings = 63  ( 157 )  Summary  = 64  ( 157 )
 CHECKSHAPE  : Wires    = 0  ( 0 )  Faces    = 0  ( 0 )  Shells   = 0  ( 0 )   Solids   = 0 ( 0 )
 NBSHAPES    : Solid    = 1  ( 1 )  Shell    = 1  ( 1 )  Face     = 956  ( 956 ) 
 STATSHAPE   : Solid    = 1  ( 1 )  Shell    = 1  ( 1 )  Face     = 956  ( 956 )   FreeWire = 0  ( 0 ) 
-TOLERANCE   : MaxTol   = 0.008481946718  (  0.05394823207 )  AvgTol   =  0.0001239210367  (  0.0004089750747 )
+TOLERANCE   : MaxTol   = 0.008481946718  (  0.01167623167 )  AvgTol   =  0.000123986292  (  0.0003770309367 )
 LABELS      : N0Labels = 1  ( 1 )  N1Labels = 0  ( 0 )  N2Labels = 0  ( 0 )   TotalLabels = 1  ( 1 )   NameLabels = 1  ( 1 )   ColorLabels = 0  ( 0 )   LayerLabels = 0  ( 0 )
 PROPS       : Centroid = 0  ( 0 )  Volume   = 0  ( 0 )  Area     = 0  ( 0 )
 NCOLORS     : NColors  = 0  ( 0 )

tests/de/step_4/H1

@@ -1,13 +1,16 @@
 # !!!! This file is generated automatically, do not edit manually! See end script
+puts "TODO CR23096 ALL: TPSTAT : Faulty" 
+
+
 set filename Inventor_Engine.stp
 
 set ref_data {
 DATA        : Faulties = 0  ( 0 )  Warnings = 0  ( 0 )  Summary  = 0  ( 0 )
-TPSTAT      : Faulties = 0  ( 0 )  Warnings = 456  ( 560 )  Summary  = 456  ( 560 )
+TPSTAT      : Faulties = 1  ( 0 )  Warnings = 455  ( 560 )  Summary  = 456  ( 560 )
 CHECKSHAPE  : Wires    = 6  ( 6 )  Faces    = 6  ( 6 )  Shells   = 0  ( 0 )   Solids   = 0 ( 0 )
 NBSHAPES    : Solid    = 47  ( 47 )  Shell    = 47  ( 47 )  Face     = 4454  ( 4454 ) 
 STATSHAPE   : Solid    = 80  ( 80 )  Shell    = 80  ( 80 )  Face     = 5356  ( 5356 )   FreeWire = 0  ( 0 ) 
-TOLERANCE   : MaxTol   =     2.37122237  (    2.449305641 )  AvgTol   =  0.002570949956  (  0.002589629313 )
+TOLERANCE   : MaxTol   =    2.371238233  (    2.449305641 )  AvgTol   =  0.001672277308  (  0.002589629313 )
 LABELS      : N0Labels = 52  ( 52 )  N1Labels = 86  ( 86 )  N2Labels = 0  ( 0 )   TotalLabels = 138  ( 138 )   NameLabels = 136  ( 136 )   ColorLabels = 47  ( 47 )   LayerLabels = 0  ( 0 )
 PROPS       : Centroid = 0  ( 0 )  Volume   = 0  ( 0 )  Area     = 0  ( 0 )
 NCOLORS     : NColors  = 11  ( 11 )

tests/de/step_5/A1

@@ -7,11 +7,11 @@ set filename Z8INV5.stp
 
 set ref_data {
 DATA        : Faulties = 0  ( 0 )  Warnings = 0  ( 0 )  Summary  = 0  ( 0 )
-TPSTAT      : Faulties = 0  ( 0 )  Warnings = 120  ( 620 )  Summary  = 120  ( 620 )
+TPSTAT      : Faulties = 0  ( 0 )  Warnings = 121  ( 620 )  Summary  = 121  ( 620 )
-CHECKSHAPE  : Wires    = 15  ( 16 )  Faces    = 17  ( 18 )  Shells   = 1  ( 1 )   Solids   = 0 ( 0 )
+CHECKSHAPE  : Wires    = 15  ( 16 )  Faces    = 18  ( 18 )  Shells   = 1  ( 1 )   Solids   = 0 ( 0 )
-NBSHAPES    : Solid    = 22  ( 22 )  Shell    = 25  ( 24 )  Face     = 1520  ( 1519 ) 
+NBSHAPES    : Solid    = 22  ( 22 )  Shell    = 25  ( 24 )  Face     = 1521  ( 1519 ) 
-STATSHAPE   : Solid    = 22  ( 22 )  Shell    = 25  ( 24 )  Face     = 1520  ( 1519 )   FreeWire = 0  ( 0 ) 
+STATSHAPE   : Solid    = 22  ( 22 )  Shell    = 25  ( 24 )  Face     = 1521  ( 1519 )   FreeWire = 0  ( 0 ) 
-TOLERANCE   : MaxTol   =    7.499684301  (    7.499684301 )  AvgTol   =   0.03452373473  (   0.03544461059 )
+TOLERANCE   : MaxTol   =    7.499684301  (    7.499684301 )  AvgTol   =   0.03357316863  (   0.03544461059 )
 LABELS      : N0Labels = 25  ( 25 )  N1Labels = 23  ( 23 )  N2Labels = 0  ( 0 )   TotalLabels = 48  ( 48 )   NameLabels = 48  ( 48 )   ColorLabels = 0  ( 0 )   LayerLabels = 0  ( 0 )
 PROPS       : Centroid = 0  ( 0 )  Volume   = 0  ( 0 )  Area     = 0  ( 0 )
 NCOLORS     : NColors  = 0  ( 0 )