Getting data from IGES files

Hello Vladimir,

With the code you posted you can read only the geometry. To have names and colors, you can use XDE (https://dev.opencascade.org/doc/overview/html/occt_user_guides__xde.html). Check out IGESCAFControl_Reader utility which reads IGES files with all metadata to an XDE document.

To produce a tessellation, you can use BRepMesh_IncrementalMesh. Notice that tessellation will be built after IGES loading, so it is not somewhat stored in the file initially. Then, to get sub-shapes like vertices or faces, you may use TopExp package.

Regards,
Qr.

Here is some code snippet you might want to look at:

bool ImporterExporter::getIGESShapeColor(
        const Handle(IGESData_IGESEntity)& shapeEntity,
        const Handle(Interface_InterfaceModel)& model, Quantity_NameOfColor& color)
{
    int colorRank = shapeEntity->RankColor();
    if (colorRank >= 0)
    {
        IGESSelect_SignColor entityRedColorSigner(4);
        std::string red = entityRedColorSigner.Value(shapeEntity, model);
        if (red.empty())
        {
            return false;
        }
        IGESSelect_SignColor entityGreenColorSigner(5);
        std::string green = entityGreenColorSigner.Value(shapeEntity, model);
        if (green.empty())
        {
            return false;
        }
        IGESSelect_SignColor entityBlueColorSigner(6);
        std::string blue = entityBlueColorSigner.Value(shapeEntity, model);
        if (blue.empty())
        {
            return false;
        }
        double redValue = std::stod(red) / 100.0;
        double greenValue = std::stod(green) / 100.0;
        double blueValue = std::stod(blue) / 100.0;
        Quantity_Color shapeColor(redValue, greenValue, blueValue,
                Quantity_TOC_RGB);
        color = shapeColor.Name();
        return true;
    }
    else
    {
        const Handle(IGESData_ColorEntity)& colorEntity = shapeEntity->Color();
        if (colorEntity.IsNull())
        {
            return false;
        }
        else
        {
            Handle(IGESGraph_Color) colorGraph = Handle(IGESGraph_Color)::DownCast(
                    colorEntity);
            if (colorGraph.IsNull())
            {
                return false;
            }
            else
            {
                double red;
                double green;
                double blue;
                colorGraph->RGBIntensity(red, green, blue);
                red = red / 100.00;
                green = green / 100.00;
                blue = blue / 100.00;
                Quantity_Color shapeQuantityColor(red, green, blue, Quantity_TOC_RGB);
                color = shapeQuantityColor.Name();
                return true;
            }
        }
    }
    return false;
}

std::string ImporterExporter::getIGESShapeName(const IGESControl_Reader& reader,
        const TopoDS_Shape& shape, Handle(IGESData_IGESEntity)& shapeEntity)
{
    const Handle(XSControl_WorkSession)& workSession = reader.WS();
    const Handle(XSControl_TransferReader)& transferReader =
            workSession->TransferReader();
    const Handle(Transfer_TransientProcess)& readerTransientProcess =
            transferReader->TransientProcess();
    shapeEntity = Handle(IGESData_IGESEntity)::DownCast(
            transferReader->EntityFromShapeResult(shape, -1));
    
    if (shapeEntity.IsNull())
    {
        return getDefaultShapeName(shape);
    }
    if (shapeEntity->HasName())
    {
        return shapeEntity->NameValue()->String().ToCString();
    }
    else
    {
        return getDefaultShapeName(shape);
    }
}

It seems you're missing TKMesh.lib in your linker's input.

First, I would recommend you to start using Draw for visualization of XDE structure. In Draw you can do the following:

> ReadIges [filename] doc # read IGES with all metadata to OCAF document
> XShow doc # show assembly in 3D viewer
> DFBrowse doc # show OCAF structure

You have to understand the XDE structure in order to learn how to iterate an assembly. Here is a sample code how you can do that. To understand better what is "free shape", "reference", "component", etc., there is no any better way than checking out the OpenCascade's sources.

// This function iterates XDE starting from the root items (empty "rootEntry").
void IterateBranch(const TCollection_AsciiString& rootEntry,
                   const TCollection_AsciiString& parentItem)
{
  Handle(TDocStd_Document)  Doc       = ...;
  Handle(XCAFDoc_ShapeTool) ShapeTool = ...;
  //
  TDF_LabelSequence Labels;
  if ( rootEntry.IsEmpty() )
  {
    // Get list of roots
    ShapeTool->GetFreeShapes(Labels);
  }
  else
  {
    // Access label by its ID
    TDF_Label RootLabel;
    TDF_Tool::Label(Doc->Main().Data(), rootEntry, RootLabel);

    // Access all components of an assembly
    if ( ShapeTool->IsAssembly(RootLabel) )
      ShapeTool->GetComponents(RootLabel, Labels);
  }

  // Iterate over the root entities
  for ( int lit = 1; lit <= Labels.Length(); ++lit )
  {
    TDF_Label L = Labels.Value(lit);
    //
    TCollection_AsciiString RefName, EntryId, RefEntryId, Name;
    Handle(TDataStd_Name) NodeName;

    TDF_Tool::Entry(L, EntryId);
    if ( ShapeTool->IsReference(L) ) // It is a reference to a part with location
    {
      // NAME OF THE REFERENCE
      if ( L.FindAttribute(TDataStd_Name::GetID(), NodeName) )
        RefName = TCollection_AsciiString( NodeName->Get() );

      TDF_Label RefLabel;
      if ( ShapeTool->GetReferredShape(L, RefLabel) ) // Get the real underlying part
      {
        L = RefLabel;
        TDF_Tool::Entry(RefLabel, RefEntryId);
      }
    }

    // NAME OF THE PART
    if ( L.FindAttribute(TDataStd_Name::GetID(), NodeName) )
    {
      Name = TCollection_AsciiString( NodeName->Get() );

      // Trim spaces
      RefName.RightAdjust();
      RefName.LeftAdjust();

      if ( !RefName.IsEmpty()           &&
            RefName.Search("=>[0:") != 1 &&
           !IsEqual(RefName, Name)  )
      {
        Name += TCollection_AsciiString (" [") + RefName + "]";
      }
    }

    if ( RefEntryId.IsEmpty() )
      RefEntryId = EntryId;

    // Build path to entry in the assembly tree
    if ( !parentItem.IsEmpty() )
    {
      EntryId.Prepend("/");
      EntryId.Prepend(parentItem);
    }

    // Continue iteration recursively
    IterateBranch(RefEntryId, EntryId);
  }
}