Can't set Line width using V3d_View with QOpenGLWidget

Francois Lauzon
Fri, 12/10/2021 - 16:52

Forums:

Hello,
I have migrate my Qt/OCC integration from V3d_View/QWidget to V3d_View/QOpenGLWidget like done in the OcctQtViewer sample application https://github.com/gkv311/occt-samples-qopenglwidget but now the linewidth of wireframe shape is not working anymore (see difference in attached image, left is V3d_View/QOpenGLWidget and right is V3d_View/QWidget from my application before I migrate).
I am using OCC 7.6.0 for my application. I tested the following snippet:
{
// dummy shape for testing
TopoDS_Shape aBox = BRepPrimAPI_MakeBox (100.0, 50.0, 90.0).Shape();
Handle(AIS_Shape) aShape = new AIS_Shape (aBox);
aShape->Attributes()->SetupOwnFaceBoundaryAspect();
aShape->Attributes()->UnFreeBoundaryAspect()->SetWidth(5);
aShape->Attributes()->SetUnFreeBoundaryAspect(aShape->Attributes()->UnFreeBoundaryAspect());
myContext->Display (aShape, AIS_WireFrame, 0, false);
}

So line width is not working, but I tested point size (using a vertex instead of the box shape) and the point size is working.

Does anyone have any clues on why it is not working and how to fix this, is it a bug?
Best regards,
François.

Attachments:

line-width-difference.png

Kirill Gavrilov
Fri, 12/10/2021 - 21:12

What "About sample" shows you about OpenGL / prints into console?

Francois Lauzon
Fri, 12/10/2021 - 21:38

I have attached a screenshot of the "About sample".
Here is a similar output from the application with V3d_View/QWidget integration:
2021-12-10 13:36:31.776 prt critical thread=42292: OpenGL informations...
2021-12-10 13:36:31.827 prt critical thread=42292: GLvendor: ATI Technologies Inc.
2021-12-10 13:36:31.828 prt critical thread=42292: GLdevice: Radeon RX Vega
2021-12-10 13:36:31.830 prt critical thread=42292: GLversion: 4.6.14761 Compatibility Profile Context 21.11.1 30.0.13033.1000
2021-12-10 13:36:31.831 prt critical thread=42292: GLSLversion: 4.60
2021-12-10 13:36:31.832 prt critical thread=42292: Max texture size: 16384
2021-12-10 13:36:31.834 prt critical thread=42292: Max FBO dump size: 16384x16384
2021-12-10 13:36:31.835 prt critical thread=42292: Max combined texture units: 160
2021-12-10 13:36:31.836 prt critical thread=42292: Max MSAA samples: 8
2021-12-10 13:36:31.837 prt critical thread=42292: Viewport: 779x513
2021-12-10 13:36:31.839 prt critical thread=42292: GPU memory: 8176 MiB
2021-12-10 13:36:31.840 prt critical thread=42292: ResolutionRatio: 1

Attachments:

about.png

Kirill Gavrilov
Fri, 12/10/2021 - 23:59

Qt has quite weird interface to select Core / Compatible profiles in OpenGL. Just comment the line "QSurfaceFormat::setVersion()" to get Compatible Profile which supports line width.

  //aGlFormat.setVersion (4, 5);
  aGlFormat.setProfile (myIsCoreProfile ? QSurfaceFormat::CoreProfile : QSurfaceFormat::CompatibilityProfile);

Francois Lauzon
Sat, 12/11/2021 - 00:03

Thank you Kirill, now it is working properly!

François.

Liu Yang
Mon, 11/03/2025 - 09:09

Is it possible to set line width in Core profile? In the following code, the line width is not working in core profile, but it works in compatible profile.

void AISElem::Compute(const Handle(PrsMgr_PresentationManager) & prsMgr, const Handle(Prs3d_Presentation) & prs, const Standard_Integer mode)
{
    prs->Clear();

    Handle(Graphic3d_Group) edgeGroup = prs->NewGroup();

    int lineWidth = 10;
    Handle(Graphic3d_AspectLine3d) lineAspect =
        new Graphic3d_AspectLine3d(Quantity_NOC_BLUE, Aspect_TOL_SOLID, lineWidth);
    edgeGroup->SetGroupPrimitivesAspect(lineAspect);

    Handle(Graphic3d_ArrayOfSegments) segArray =
        new Graphic3d_ArrayOfSegments(2);

    gp_Pnt pnt1(0, 0, 0);
    gp_Pnt pnt2(100, 100, 100);

    segArray->AddVertex(pnt1);
    segArray->AddVertex(pnt2);

    edgeGroup->AddPrimitiveArray(segArray);
}

gkv311 n
Tue, 11/04/2025 - 09:08

Liu Yang wrote:

Is it possible to set line width in Core profile?

No it's impossible right now. Until OCCT will not implement emulated wide lines. Though you may draw thick mesh edges.