OBJ Importing and Displaying

Thank you both for your quick replies. Not quite there yet, but I think you were both right...

I tried the easy way first (Simons). This loaded my model on first attempt!! But, it took doing this to find that rotation and scaling are completely to-cock. Hence a more comprehensive solution is needed (gkv's). I'm currently working through this, but will post the results when I get something going...

Mat

ok, I'll try to reply again, this time using language which doesn't flag me for moderation :)

Thanks for both for the replies - you are both right. First example code got me up the running instantly - which immediately showed I had a scale and rotation issue with the .OBJ Importing - which pushed me to the bigger implementation. Took a little playing around, but I've got something up and running using this code:

//-----------------------------------------------------------------------------

//! Open OBJ file.
bool CBlah::ImportOBJ (const TCollection_AsciiString& theFilePath)
{
    // create an empty XCAF document
    createXCAFApp();
    newDocument();

    // read and translate STEP file into XCAF document
    RWObj_CafReader aReader;
    aReader.SetDocument(myXdeDoc);
    aReader.Perform(theFilePath, Message_ProgressRange());

    TDF_Label mainLabel = myXdeDoc->Main();
    Handle(XCAFDoc_ShapeTool) myShapeTool = XCAFDoc_DocumentTool::ShapeTool(mainLabel);
    Handle(XCAFDoc_ColorTool) myColors = XCAFDoc_DocumentTool::ColorTool(mainLabel);
    Handle(XCAFDoc_MaterialTool) myMaterial = XCAFDoc_DocumentTool::MaterialTool (mainLabel);

    TDF_LabelSequence FreeShape;
    myShapeTool->GetFreeShapes(FreeShape);

    //rotate and scale OBJ to correct for Y-up and m not mm scale
    gp_Trsf trsf;
    trsf.SetRotation(gp_Quaternion(0.7071, 0, 0, 0.7071));
    trsf.SetScaleFactor(1000);

    int Roots = FreeShape.Length();
    for (int i = 1; i <= Roots; i++)
    {
        TDF_Label label = FreeShape.Value(i);
        Handle(XCAFPrs_AISObject) displayedShape = new XCAFPrs_AISObject(label);
        displayedShape->SetLocalTransformation(trsf);
        myContext->Display(displayedShape, true);
    }
    return true;
}
//-----------------------------------------------------------------------

So, progressing well. The next hurdles start to get interesting:
1. Material is being loaded using this function, but not displayed - any ideas?
(I know its being loaded because it complains when the file paths are missing)
2. To solve the rotation problem I want to auto-detect the coordinate system by measuring the object and detecting the longest edge. We're starting to swerve a little off-topic here, but do you know any way to extract bounding-box dimensions from an AIS or Topo shape? Once again, my thoughts are about manually calculating from points, but it feels like something there is a secret function for (if only I knew where to look :))

cheers

Mat

coming back around to this problem again...

I can load in an OBJ file no problems, it detects when the associated material files are not present (which I therefore assume it finds them when they are present), but the visual presentation of the object is a complete white-out.

Is there a missing link between the loading of the object (XCAFDoc_ShapeTool) and the loading of the material (XCAFDoc_MaterialTool) - do I need to cross-assign these somewhere?

Anyone any ideas?

Mat

    try
    {
        // read and translate file into XCAF document
        RWObj_CafReader aReader;
        aReader.SetDocument(myXdeDoc);
        aReader.Perform(theFilePath, Message_ProgressRange());

        TDF_Label mainLabel = myXdeDoc->Main();
        Handle(XCAFDoc_ShapeTool) myShapeTool = XCAFDoc_DocumentTool::ShapeTool(mainLabel);
        Handle(XCAFDoc_ColorTool) myColors = XCAFDoc_DocumentTool::ColorTool(mainLabel);
        Handle(XCAFDoc_MaterialTool) myMaterial = XCAFDoc_DocumentTool::MaterialTool (mainLabel);
     
        TDF_LabelSequence FreeShape;
        myShapeTool->GetFreeShapes(FreeShape);

        if (FreeShape.Length() < 1)
            return false;

        TDF_Label label = FreeShape.Value(1); //only process first root

        TopoDS_Shape localShape;
        XCAFDoc_ShapeTool::GetShape(label, localShape);
        if (localShape.IsNull())
            return false;

        gp_Trsf t = calculateTransformNeeded(localShape); //calculates transformation needed for mm/cm/m scale, rotation, etc

        Handle(XCAFPrs_AISObject) displayedShape = new XCAFPrs_AISObject(label);

        displayedShape->SetLocalTransformation(t); //applies transformation

        m_3dshape = displayedShape;  //calls ->Display() on this later. 

    }
    catch (Standard_Failure const& theFailure)
    {
        Message::SendFail() << "Exception raised during OBJ import\n[" << theFailure.GetMessageString() << "]\n" << theFilePath;
        return false;
    }