Data Exchange, Step Export - Apply a scaling transformation (#513)

Add possibility to export scaling factor into the STEP file as a cartesian_transformation_operator_3d.
Add flag for turning on/off (on by default) this behavior.

src/DataExchange/TKDEIGES/DEIGES/DEIGES_Parameters.hxx

@@ -126,4 +126,4 @@ public:
   // clang-format on
 };
 
-#endif // _DESTEP_Parameters_HeaderFile
+#endif // _DEIGES_Parameters_HeaderFile

src/DataExchange/TKDESTEP/DESTEP/DESTEP_ConfigurationNode.cxx

@@ -200,6 +200,8 @@ bool DESTEP_ConfigurationNode::Load(const Handle(DE_ConfigurationContext)& theRe
                                                        aScope);
   InternalParameters.CleanDuplicates =
     theResource->BooleanVal("write.cleanduplicates", InternalParameters.CleanDuplicates, aScope);
+  InternalParameters.WriteScalingTrsf =
+    theResource->BooleanVal("write.scaling.trsf", InternalParameters.WriteScalingTrsf, aScope);
 
   return DE_ShapeFixConfigurationNode::Load(theResource);
 }
@@ -589,6 +591,13 @@ TCollection_AsciiString DESTEP_ConfigurationNode::Save() const
   aResult += aScope + "write.cleanduplicates :\t " + InternalParameters.CleanDuplicates + "\n";
   aResult += "!\n";
 
+  aResult += "!\n";
+  aResult +=
+    "!Defines export scaling factor in transformation as Cartesian Operator (On) or skip(Off)";
+  aResult += "!Default value: 1(\"On\"). Available values: 0(\"OFF\"), 1(\"On\")\n";
+  aResult += aScope + "write.scaling.trsf :\t " + InternalParameters.WriteScalingTrsf + "\n";
+  aResult += "!\n";
+
   aResult += DE_ShapeFixConfigurationNode::Save();
 
   aResult += "!*****************************************************************************\n";

src/DataExchange/TKDESTEP/DESTEP/DESTEP_Parameters.hxx

@@ -203,6 +203,7 @@ public:
   bool WriteVisMaterial = false;  //<! VisMaterialMode is used to indicate write Visual Material or not
   STEPControl_StepModelType WriteModelType = STEPControl_AsIs; //<! Gives you the choice of translation mode for an Open CASCADE shape that is being translated to STEP
   bool CleanDuplicates = false; //<! Indicates whether to remove duplicate entities from the STEP file
+  bool WriteScalingTrsf = true; //<! Indicates if scaling should be written as Cartesian Operator or skipped
   // clang-format on
 };
 

src/DataExchange/TKDESTEP/GeomToStep/FILES.cmake

@@ -25,6 +25,8 @@ set(OCCT_GeomToStep_FILES
   GeomToStep_MakeBSplineSurfaceWithKnotsAndRationalBSplineSurface.hxx
   GeomToStep_MakeCartesianPoint.cxx
   GeomToStep_MakeCartesianPoint.hxx
+  GeomToStep_MakeCartesianTransformationOperator.cxx
+  GeomToStep_MakeCartesianTransformationOperator.hxx
   GeomToStep_MakeCircle.cxx
   GeomToStep_MakeCircle.hxx
   GeomToStep_MakeCircle_gen.pxx

src/DataExchange/TKDESTEP/GeomToStep/GeomToStep_MakeCartesianTransformationOperator.cxx

@@ -0,0 +1,49 @@
+// Copyright (c) 2025 OPEN CASCADE SAS
+//
+// This file is part of Open CASCADE Technology software library.
+//
+// This library is free software; you can redistribute it and/or modify it under
+// the terms of the GNU Lesser General Public License version 2.1 as published
+// by the Free Software Foundation, with special exception defined in the file
+// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
+// distribution for complete text of the license and disclaimer of any warranty.
+//
+// Alternatively, this file may be used under the terms of Open CASCADE
+// commercial license or contractual agreement.
+
+#include <GeomToStep_MakeCartesianTransformationOperator.hxx>
+
+#include <GeomToStep_MakeCartesianPoint.hxx>
+#include <GeomToStep_MakeDirection.hxx>
+#include <StepGeom_CartesianTransformationOperator3d.hxx>
+
+//=============================================================================
+
+GeomToStep_MakeCartesianTransformationOperator::GeomToStep_MakeCartesianTransformationOperator(
+  const gp_Trsf&          theTrsf,
+  const StepData_Factors& theLocalFactors)
+{
+  gp_Trsf anInvTrsf = theTrsf;
+  anInvTrsf.Invert();
+  Standard_Real aScale   = anInvTrsf.ScaleFactor();
+  gp_Mat        anInvMat = anInvTrsf.HVectorialPart();
+
+  gp_Mat aMat         = theTrsf.HVectorialPart();
+  gp_XYZ aTranslation = anInvTrsf.TranslationPart().Multiplied(aMat);
+  aTranslation.Reverse();
+
+  GeomToStep_MakeCartesianPoint aMkPoint(aTranslation, theLocalFactors.LengthFactor());
+  GeomToStep_MakeDirection      aMkDir1(anInvMat.Row(1));
+  GeomToStep_MakeDirection      aMkDir2(anInvMat.Row(2));
+  GeomToStep_MakeDirection      aMkDir3(anInvMat.Row(3));
+
+  myTrsfOp = new StepGeom_CartesianTransformationOperator3d();
+  myTrsfOp->SetName(new TCollection_HAsciiString(""));
+  myTrsfOp->SetAxis1(aMkDir1.Value());
+  myTrsfOp->SetAxis2(aMkDir2.Value());
+  myTrsfOp->SetAxis3(aMkDir3.Value());
+  myTrsfOp->SetLocalOrigin(aMkPoint.Value());
+  myTrsfOp->SetScale(aScale);
+
+  done = Standard_True;
+}

src/DataExchange/TKDESTEP/GeomToStep/GeomToStep_MakeCartesianTransformationOperator.hxx

@@ -0,0 +1,53 @@
+// Copyright (c) 2025 OPEN CASCADE SAS
+//
+// This file is part of Open CASCADE Technology software library.
+//
+// This library is free software; you can redistribute it and/or modify it under
+// the terms of the GNU Lesser General Public License version 2.1 as published
+// by the Free Software Foundation, with special exception defined in the file
+// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
+// distribution for complete text of the license and disclaimer of any warranty.
+//
+// Alternatively, this file may be used under the terms of Open CASCADE
+// commercial license or contractual agreement.
+
+#ifndef _GeomToStep_MakeCartesianTransformationOperator_HeaderFile
+#define _GeomToStep_MakeCartesianTransformationOperator_HeaderFile
+
+#include <Standard.hxx>
+#include <Standard_DefineAlloc.hxx>
+#include <Standard_Handle.hxx>
+
+#include <GeomToStep_Root.hxx>
+#include <StepData_StepModel.hxx>
+#include <StepGeom_CartesianTransformationOperator3d.hxx>
+
+class gp_Trsf;
+
+//! This class creates a cartesian_transformation_operator from gp_Trsf.
+//! This entity is used in OCCT to implement a transformation with scaling.
+//! In case of other inputs without scaling use Axis2Placement3d.
+class GeomToStep_MakeCartesianTransformationOperator : public GeomToStep_Root
+{
+public:
+  DEFINE_STANDARD_ALLOC
+
+  //! Main constructor.
+  //! @param[in] theTrsf Transformation to create the operator from it.
+  //! @param[in] theLocalFactors Unit scale factors
+  Standard_EXPORT GeomToStep_MakeCartesianTransformationOperator(
+    const gp_Trsf&          theTrsf,
+    const StepData_Factors& theLocalFactors = StepData_Factors());
+
+  //! Returns the created entity.
+  //! @return The created value.
+  inline const Handle(StepGeom_CartesianTransformationOperator3d)& Value() const
+  {
+    return myTrsfOp;
+  }
+
+private:
+  Handle(StepGeom_CartesianTransformationOperator3d) myTrsfOp;
+};
+
+#endif // _GeomToStep_MakeCartesianTransformationOperator_HeaderFile

src/DataExchange/TKDESTEP/STEPConstruct/STEPConstruct_Assembly.cxx

@@ -22,6 +22,7 @@
 #include <StepBasic_ProductDefinition.hxx>
 #include <STEPConstruct_Assembly.hxx>
 #include <StepGeom_Axis2Placement3d.hxx>
+#include <StepGeom_CartesianTransformationOperator3d.hxx>
 #include <StepRepr_ItemDefinedTransformation.hxx>
 #include <StepRepr_NextAssemblyUsageOccurrence.hxx>
 #include <StepRepr_ProductDefinitionShape.hxx>
@@ -51,8 +52,25 @@ void STEPConstruct_Assembly::Init(const Handle(StepShape_ShapeDefinitionRepresen
   thesr   = Handle(StepShape_ShapeRepresentation)::DownCast(aSDR->UsedRepresentation());
   thesr0  = Handle(StepShape_ShapeRepresentation)::DownCast(SDR0->UsedRepresentation());
   theval.Nullify();
-  theax0 = Ax0;
+  theax0            = Ax0;
-  theloc = AxLoc;
+  theloc            = AxLoc;
+  myIsCartesianTrsf = false;
+}
+
+//=================================================================================================
+
+void STEPConstruct_Assembly::Init(
+  const Handle(StepShape_ShapeDefinitionRepresentation)&    aSDR,
+  const Handle(StepShape_ShapeDefinitionRepresentation)&    SDR0,
+  const Handle(StepGeom_CartesianTransformationOperator3d)& theTrsfOp)
+{
+  thesdr  = aSDR;
+  thesdr0 = SDR0;
+  thesr   = Handle(StepShape_ShapeRepresentation)::DownCast(aSDR->UsedRepresentation());
+  thesr0  = Handle(StepShape_ShapeRepresentation)::DownCast(SDR0->UsedRepresentation());
+  theval.Nullify();
+  myTrsfOp          = theTrsfOp;
+  myIsCartesianTrsf = true;
 }
 
 //=================================================================================================
@@ -91,10 +109,19 @@ void STEPConstruct_Assembly::MakeRelationship()
   PDS->Init(pdsname, Standard_True, pdsdesc, CD);
 
   // create transformation
-  Handle(StepRepr_ItemDefinedTransformation) ItemDef = new StepRepr_ItemDefinedTransformation;
+  Handle(Standard_Transient) aTrsfItem;
-  Handle(TCollection_HAsciiString)           idname  = new TCollection_HAsciiString("");
+  if (!myIsCartesianTrsf)
-  Handle(TCollection_HAsciiString)           idescr  = new TCollection_HAsciiString("");
+  {
-  ItemDef->Init(idname, idescr, theax0, theloc);
+    Handle(StepRepr_ItemDefinedTransformation) ItemDef = new StepRepr_ItemDefinedTransformation;
+    Handle(TCollection_HAsciiString)           idname  = new TCollection_HAsciiString("");
+    Handle(TCollection_HAsciiString)           idescr  = new TCollection_HAsciiString("");
+    ItemDef->Init(idname, idescr, theax0, theloc);
+    aTrsfItem = ItemDef;
+  }
+  else
+  {
+    aTrsfItem = myTrsfOp;
+  }
 
   // create SRRWT
   Handle(StepRepr_ShapeRepresentationRelationshipWithTransformation) SRRWT =
@@ -102,7 +129,7 @@ void STEPConstruct_Assembly::MakeRelationship()
   Handle(TCollection_HAsciiString) stname = new TCollection_HAsciiString("");
   Handle(TCollection_HAsciiString) stescr = new TCollection_HAsciiString("");
   StepRepr_Transformation          StepTrans;
-  StepTrans.SetValue(ItemDef);
+  StepTrans.SetValue(aTrsfItem);
   SRRWT->Init(stname, stescr, thesr, thesr0, StepTrans);
 
   // create CDSR (final result, root)

src/DataExchange/TKDESTEP/STEPConstruct/STEPConstruct_Assembly.hxx

@@ -24,6 +24,7 @@
 class StepShape_ShapeDefinitionRepresentation;
 class StepShape_ShapeRepresentation;
 class StepGeom_Axis2Placement3d;
+class StepGeom_CartesianTransformationOperator3d;
 class StepRepr_NextAssemblyUsageOccurrence;
 class StepShape_ContextDependentShapeRepresentation;
 class Interface_Graph;
@@ -52,6 +53,14 @@ public:
                             const Handle(StepGeom_Axis2Placement3d)&               Ax0,
                             const Handle(StepGeom_Axis2Placement3d)&               Loc);
 
+  //! Initialises with starting values
+  //! theTrsfOp : local transformation to apply, may have scaling factor
+  //! Makes a MappedItem
+  //! Resulting Value is returned by ItemValue
+  Standard_EXPORT void Init(const Handle(StepShape_ShapeDefinitionRepresentation)&    theSR,
+                            const Handle(StepShape_ShapeDefinitionRepresentation)&    theSDR0,
+                            const Handle(StepGeom_CartesianTransformationOperator3d)& theTrsfOp);
+
   //! Make a (ShapeRepresentationRelationship,...WithTransformation)
   //! Resulting Value is returned by ItemValue
   Standard_EXPORT void MakeRelationship();
@@ -74,13 +83,15 @@ public:
 
 protected:
 private:
-  Handle(StepShape_ShapeDefinitionRepresentation) thesdr;
+  Handle(StepShape_ShapeDefinitionRepresentation)    thesdr;
-  Handle(StepShape_ShapeDefinitionRepresentation) thesdr0;
+  Handle(StepShape_ShapeDefinitionRepresentation)    thesdr0;
-  Handle(StepShape_ShapeRepresentation)           thesr;
+  Handle(StepShape_ShapeRepresentation)              thesr;
-  Handle(StepShape_ShapeRepresentation)           thesr0;
+  Handle(StepShape_ShapeRepresentation)              thesr0;
-  Handle(Standard_Transient)                      theval;
+  Handle(Standard_Transient)                         theval;
-  Handle(StepGeom_Axis2Placement3d)               theloc;
+  Handle(StepGeom_Axis2Placement3d)                  theloc;
-  Handle(StepGeom_Axis2Placement3d)               theax0;
+  Handle(StepGeom_Axis2Placement3d)                  theax0;
+  Handle(StepGeom_CartesianTransformationOperator3d) myTrsfOp;
+  bool                                               myIsCartesianTrsf;
 };
 
 #endif // _STEPConstruct_Assembly_HeaderFile

src/DataExchange/TKDESTEP/STEPControl/STEPControl_ActorWrite.cxx

@@ -26,6 +26,7 @@
 #include <Geom_Plane.hxx>
 #include <Geom_Surface.hxx>
 #include <GeomToStep_MakeAxis2Placement3d.hxx>
+#include <GeomToStep_MakeCartesianTransformationOperator.hxx>
 #include <Interface_Macros.hxx>
 #include <Interface_MSG.hxx>
 #include <Message_ProgressScope.hxx>
@@ -41,6 +42,7 @@
 #include <STEPControl_StepModelType.hxx>
 #include <StepData_StepModel.hxx>
 #include <StepGeom_Axis2Placement3d.hxx>
+#include <StepGeom_CartesianTransformationOperator3d.hxx>
 #include <StepGeom_GeomRepContextAndGlobUnitAssCtxAndGlobUncertaintyAssCtx.hxx>
 #include <StepGeom_Point.hxx>
 #include <StepRepr_ShapeRepresentationRelationship.hxx>
@@ -1656,8 +1658,8 @@ Handle(Transfer_Binder) STEPControl_ActorWrite::TransferCompound(
   Message_ProgressScope aPS(theProgress, NULL, nbs);
   for (i = 1; i <= nbs && aPS.More(); i++)
   {
-    Handle(TransferBRep_ShapeMapper)  subs = TransferBRep::ShapeMapper(FP, RepItemSeq->Value(i));
+    Handle(TransferBRep_ShapeMapper) subs = TransferBRep::ShapeMapper(FP, RepItemSeq->Value(i));
-    Handle(StepGeom_Axis2Placement3d) AX1;
+    Handle(StepGeom_GeometricRepresentationItem) AX1;
 
     Handle(Transfer_Binder) bnd = TransferSubShape(subs,
                                                    SDR0,
@@ -1709,7 +1711,7 @@ Handle(Transfer_Binder) STEPControl_ActorWrite::TransferCompound(
 Handle(Transfer_Binder) STEPControl_ActorWrite::TransferSubShape(
   const Handle(Transfer_Finder)&                         start,
   const Handle(StepShape_ShapeDefinitionRepresentation)& SDR0,
-  Handle(StepGeom_Axis2Placement3d)&                     AX1,
+  Handle(StepGeom_GeometricRepresentationItem)&          AX1,
   const Handle(Transfer_FinderProcess)&                  FP,
   const StepData_Factors&                                theLocalFactors,
   const Handle(TopTools_HSequenceOfShape)&               shapeGroup,
@@ -1781,14 +1783,39 @@ Handle(Transfer_Binder) STEPControl_ActorWrite::TransferSubShape(
   //  FP->GetTypedTransient (resbind,STANDARD_TYPE(StepShape_ShapeRepresentation),resultat);
   //  sdr->SetUsedRepresentation(resultat);  // to be used by MakeItem
 
-  // make location for assembly placement
-  GeomToStep_MakeAxis2Placement3d          mkax(aLoc, theLocalFactors);
-  const Handle(StepGeom_Axis2Placement3d)& AxLoc = mkax.Value();
-  AX1                                            = AxLoc;
-
   // create assembly structures (CDSR, NAUO etc.)
   STEPConstruct_Assembly mkitem;
-  mkitem.Init(sdr, SDR0, myContext.GetDefaultAxis(), AxLoc);
+
+  // make location for assembly placement
+  if (Abs(aLoc.ScaleFactor() - 1.0) > Precision::Confusion())
+  {
+    if (aStepModel->InternalParameters.WriteScalingTrsf)
+      FP->AddWarning(
+        start,
+        "The shape has a scaling factor, exported as cartesian_transformation_operator");
+    else
+      FP->AddWarning(start, "The shape has a scaling factor, skipped");
+  }
+  if (Abs(aLoc.ScaleFactor() - 1.0) < Precision::Confusion()
+      || !aStepModel->InternalParameters.WriteScalingTrsf)
+  {
+    // create a new axis2placement3d
+    GeomToStep_MakeAxis2Placement3d mkax(aLoc, theLocalFactors);
+    mkitem.Init(sdr, SDR0, myContext.GetDefaultAxis(), mkax.Value());
+    AX1 = mkax.Value();
+  }
+  else
+  {
+    // create a new cartesian transformation
+    GeomToStep_MakeCartesianTransformationOperator aMaker(aLoc, theLocalFactors);
+    if (!aMaker.IsDone())
+    {
+      FP->AddFail(start, "The transfomation relation creation failed");
+    }
+    mkitem.Init(sdr, SDR0, aMaker.Value());
+    AX1 = aMaker.Value();
+  }
+
   mkitem.MakeRelationship();
   Handle(TColStd_HSequenceOfTransient) roots = myContext.GetRootsForAssemblyLink(mkitem);
 

src/DataExchange/TKDESTEP/STEPControl/STEPControl_ActorWrite.hxx

@@ -29,7 +29,7 @@ class Transfer_Finder;
 class Transfer_Binder;
 class Transfer_FinderProcess;
 class StepShape_ShapeDefinitionRepresentation;
-class StepGeom_Axis2Placement3d;
+class StepGeom_GeometricRepresentationItem;
 class TopoDS_Shape;
 class StepShape_NonManifoldSurfaceShapeRepresentation;
 
@@ -55,7 +55,7 @@ public:
   Standard_EXPORT Handle(Transfer_Binder) TransferSubShape(
     const Handle(Transfer_Finder)&                         start,
     const Handle(StepShape_ShapeDefinitionRepresentation)& SDR,
-    Handle(StepGeom_Axis2Placement3d)&                     AX1,
+    Handle(StepGeom_GeometricRepresentationItem)&          AX1,
     const Handle(Transfer_FinderProcess)&                  FP,
     const StepData_Factors&                                theLocalFactors = StepData_Factors(),
     const Handle(TopTools_HSequenceOfShape)&               shapeGroup      = NULL,

src/DataExchange/TKDESTEP/StepToGeom/StepToGeom.cxx

@@ -2131,6 +2131,10 @@ Standard_Boolean StepToGeom::MakeTransformation3d(
 
     const gp_Ax3 result(Pgp, D3, D1);
     CT.SetTransformation(result);
+    if (SCTO->HasScale())
+    {
+      CT.SetScaleFactor(SCTO->Scale());
+    }
     CT = CT.Inverted(); //: n8 abv 16 Feb 99: tr8_as2_db.stp: reverse for accordance with LV tool
     return Standard_True;
   }

tests/bugs/step/bug_ocp1949

@@ -0,0 +1,51 @@
+puts "================================================"
+puts "OCP-1949: Apply a scaling transformation to STEP"
+puts "================================================"
+puts ""
+
+pload OCAF
+
+Close D1 -silent
+Close D2 -silent
+
+ReadGltf D1 [locate_data_file bug_ocp1948_PSU_Cartoning_subunit__right-01.01.01.03-CART-03_green_bottom.glb]
+
+# apply parameters for tessellation export
+set conf "
+provider.STEP.OCC.write.schema :	 5
+provider.STEP.OCC.write.tessellated :	 1
+"
+LoadConfiguration ${conf} -recursive on
+param write.step.schema 5
+param write.step.tessellated 1
+
+WriteStep D1 "$imagedir/${casename}.stp"
+ReadStep D2 "$imagedir/${casename}.stp"
+
+XGetOneShape a1 D1
+XGetOneShape a2 D2
+
+# check center of gravity
+set pos1 [vprops a1]
+set pos2 [vprops a2]
+
+set REF_X [lindex $pos1  9]
+set REF_Y [lindex $pos1 12]
+set REF_Z [lindex $pos1 15]
+set tol 1e-4
+
+if {([expr abs($REF_X - [lindex $pos2  9])] > $tol) || 
+    ([expr abs($REF_Y - [lindex $pos2 12])] > $tol) ||
+    ([expr abs($REF_Z - [lindex $pos2 15])] > $tol)} {
+  puts "Error: wrong position of the imported model."
+  }
+
+# cleaning
+Close D1
+Close D2
+file delete "$imagedir/${casename}.stp"
+set conf "
+provider.STEP.OCC.write.schema :	 4
+provider.STEP.OCC.write.tessellated :	 2
+"
+LoadConfiguration ${conf} -recursive on

tests/bugs/xde/bug27142

@@ -3,7 +3,6 @@ puts "0027142: Data Exchange - add possibility to set location in XCAFDoc_ShapeT
 puts "=========="
 puts ""
 
-puts "TODO 0027142 ALL: Error: area of d1"
 puts "TODO 0027142 ALL: Error: area of d2"
 puts "TODO 0027142 ALL: Error: center of gravity"
 

tests/de_wrapper/configuration/A3

@@ -199,6 +199,7 @@ provider.STEP.OCC.write.vismaterial :	 0
 provider.STEP.OCC.write.props :	 1
 provider.STEP.OCC.write.model.type :	 0
 provider.STEP.OCC.write.cleanduplicates : 0
+provider.STEP.OCC.write.scaling.trsf : 1
 provider.STEP.OCC.healing.tolerance3d :	 1e-06
 provider.STEP.OCC.healing.max.tolerance3d :	 1
 provider.STEP.OCC.healing.min.tolerance3d :	 1e-07

tests/de_wrapper/configuration/A4

@@ -143,6 +143,7 @@ provider.STEP.OCC.write.material :	 1
 provider.STEP.OCC.write.vismaterial :	 0
 provider.STEP.OCC.write.model.type :	 0
 provider.STEP.OCC.write.cleanduplicates : 0
+provider.STEP.OCC.write.scaling.trsf : 1
 provider.STEP.OCC.healing.tolerance3d :	 1e-06
 provider.STEP.OCC.healing.max.tolerance3d :	 1
 provider.STEP.OCC.healing.min.tolerance3d :	 1e-07