Problem with STEP-Export in assembly mode

Hello everyone,

I have a problem using the STEP-Export Facilities of OpenCASCADE 5.2 with references (assembly mode on), to keep the filesize small.
When using more than a few hundred references, the TKXSBASE.dll crashes with a stack overflow.Consider the following simple example program, that writes a square of n*n boxes as references on a grid, where n is the programm argument:


//...include all relevant OCC headers here////////////////////

static TopoDS_Compound AddTestStructure(int nCount_)
BRep_Builder B;
int nCount=nCount_;
TopoDS_Compound C;
BRepPrimAPI_MakeBox mkBox(1.0, 2.0, 3.0);
for (int i=0; i for (int j=0; j gp_Trsf trsf;
trsf.SetTranslationPart(gp_Vec(5.0*i, 05.0*j, 0.0));
TopLoc_Location topLoc(trsf);
TopoDS_Shape tempShape=mkBox.Shape().Located(topLoc);
B.Add(C, tempShape);
return C;

int main( int argc, char *argv[ ])
int nCount = 10;
if (argc > 1)
nCount = atoi(argv[1]);
STEPCAFControl_Writer writer;
Handle_TDocStd_Document document;
document = new TDocStd_Document("Pace Test-StepExporter-");
Handle_XCAFDoc_ShapeTool shapeTool;
shapeTool = XCAFDoc_DocumentTool::ShapeTool(document->Main());
shapeTool->AddShape(AddTestStructure(nCount), Standard_True);
STEPControl_StepModelType mode = STEPControl_AsIs;
if (!Interface_Static::SetIVal("write.step.assembly",1)) { //assembly mode
assert(false && "failed to set assembly mode for step data");
try {
if( writer.Transfer(document, mode)) {
IFSelect_ReturnStatus stat =
} catch (Standard_Failure e) {
cout } catch(...) {
cout }
return 0;


The program will work with argument 10 (i.e. 100 cubes) but will crash with
argument 20 (i.e 400 cubes), when the default stack size on
Windows 2000 (i.e. 1MB) is used.
The problem seems to originate from a recursive call of the Handle_Transfer_Binder destructor (each Transfer_Binder owns another Handle_Transfer_Binder field), which causes the stack overflow, but I have not figured out a patch yet.
Has anyone encountered similar problems and has some ideas for a solution?
I would be very interested in your ideas and will post in return any suggestion for a patch that I come up with.


kanding's picture

I have made some changes to the TransferSubShape method of STEPControl_ActorWrite.cxx that works fine with up to a few thousand references. I will send the file with changes to anyone interested, since there seems to be no standarized way in this forum to handle contributions from the community. Just drop me a line if You are interested.


gpsunjp's picture

Hello, Kai

Could you send me( your modified source. I met the same problem.


gpsunjp's picture

Hello Kai

I tested your patch. It works fine.



Open CASCADE Support Team's picture

Dear Mr. Anding,

We appreciate your efforts to improve Open CASCADE Technology Open Source, and we welcome you to provide your solution for testing and integration into future releases of OCCT.

For that purpose, we advise you to send your correction in form of a modified source code to

We shall register a corresponding bug to give you the reference number by which you will be able to track integration of your solution consulting the Release Notes of Open CASCADE Technology. The Release Notes are regularly published on our web site at

We remind to all members of the Community that we value your efforts and we are always glad to receive your helpful contributions.

Yours sincerely,
Open CASCADE Support Team

Open CASCADE Support Team's picture

Dear Mr. Anding,

Thank you for contributing to Open CASCADE Technology!

We are pleased to inform you that you contribution has been registered as an improvement with reference number OCC7141 "STEP interface crashes exporting large assembly".

Your modification has been successfully tested for non regression and will appear in the following public version of Open CASCADE.

With best regards,
Open CASCADE Support Team