BRepAlgoAPI_Splitter with closed wire

The step file that you attached contains each face encapsulated in its own shell. It would be helpful to see the source code of your example that produced such result. Actually, splitter must split the shell in your case in two shells.

Your mistake is that you get faces from the input shell and put them in a list. In such way you have lost the initial shell. You need to create a new list and put there only the shell. And pass that list to the splitter.

Could you attach the original shell and wire before split?

Hello Michael,

BRepAlgoAPI_Splitter is not able to split the shell on parts. It splits edges, faces, solids by other arguments, but not the wires and shells. But still, the result of Splitter algorithm may be used as a base to build the desired result, but some post treatment required. The idea is to build connected blocks of shells, but avoid the input wire in the connection elements. The following code may be used for that (may contain some errors as just written in notepad so you may have to adjust it):

BRepAlgoAPI_Splitter aSplitter;
aSplitter.AddArgument(theShell);
aSplitter.AddTool(theWire);
aSplitter.Build();

if (!aSplitter.IsDone())
{
    return;
}

const TopoDS_Shape& aSplitterResult = aSplitter.Shape();

TopTools_IndexedDataMapOfShapeListOfShape aConnectionMap;
// Map shapes to find connected elements
TopExp::MapShapesAndAncestors(aSplitterResult, TopAbs_EDGE, TopAbs_FACE, aConnectionMap);

// Build map of edges from the input wire to avoid passing through its edges
// when building the resulting shells
TopTools_IndexedMapOfShape aMEAvoid;
if (const TopTools_ListOfShape* pWireImages = aSplitter.Images().Seek(theWire))
{
    for (const auto& aWireIm : *pWireImages)
    {
        TopExp::MapShapes(aWireIm, TopAbs_EDGE, aMEAvoid);
    }
}
else
{
    TopExp::MapShapes(theWire, TopAbs_EDGE, aMEAvoid);
}

// Fence map to avoid adding faces twice
TopTools_MapOfShape aMFence;

// Resulting shells
TopTools_ListOfShape aLShells;

TopExp_Explorer aExp(aSplitterResult, TopAbs_FACE);
for (; aExp.More(); aExp.Next())
{
    const TopoDS_Face& aS = TopoDS::Face(aExp.Current());
    if (!aMFence.Add(aS))
    {
        continue;
    }

    // The new shell
    TopoDS_Shell aShell;
    BRep_Builder().MakeShell(aShell);

    // Start the block
    BRep_Builder().Add(aShell, aS);

    // Look for connected parts
    TopoDS_Iterator itF(aShell);
    for (; itF.More(); itF.Next())
    {
        const TopoDS_Shape& aS1 = aItB.Value();
        TopExp_Explorer aExpSS(aS1, TopAbs_EDGE);
        for (; aExpSS.More(); aExpSS.Next())
        {
            const TopoDS_Shape& aSubS = aExpSS.Current();
            if (aMEAvoid.Contains(aSubS))
            {
                continue;
            }

            const TopTools_ListOfShape& aLS = aConnectionMap.FindFromKey(aSubS);
            TopTools_ListIteratorOfListOfShape aItLS(aLS);
            for (; aItLS.More(); aItLS.Next())
            {
                const TopoDS_Face& aS2 = TopoDS::Face(aItLS.Value());
                if (aMFence.Add(aS2))
                {
                    BRep_Builder().Add(aShell, aS2);
                }
            }
        }
    }
    // Add the block into result
    aLShells.Append(aShell);
}