# QVTKOpenGLWidget: Vertices disappear when RenderPointsAsSpheresON()

**URL:** https://discourse.vtk.org/t/qvtkopenglwidget-vertices-disappear-when-renderpointsassphereson/1007
**Category:** Support
**Created:** [May 22, 2019, 10:00am UTC](https://discourse.vtk.org/t/qvtkopenglwidget-vertices-disappear-when-renderpointsassphereson/1007 "2019-05-22T10:00:45Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![sdobashi](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/s/e9c0ed/32.png) [@sdobashi](https://discourse.vtk.org/u/sdobashi)
#### Post date: [May 22, 2019, 10:00am UTC](https://discourse.vtk.org/t/qvtkopenglwidget-vertices-disappear-when-renderpointsassphereson/1007/1 "2019-05-22T10:00:46Z")

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Hi everyone,

When using QVTKOpenGLWidget, the vertices cannot be rendered as spheres (they disappear) when I set “RenderPointsAsSpheresON()”, while they are properly rendered with vtkRenderWindow.

I want to obtain the same result as with “vtkRenderWindow” when using “vtkGenericOpenGLRenderWindow”.

Is there a workaround for this problem?  
I’m using VTK 8.2.0 and Qt 5.12.3.

I appreciate any suggestions.

Thanks in advance and best regards.

* * *

OK: vtkRenderWindow

![tube_and_sphere_vtk_OK](https://discourse.vtk.org/uploads/default/original/1X/94ef3d660eb81ef69ab9abd023208e18963bcb15.png)

NG: vtkGenericOpenGLRenderWindow (Vertices disappears)

![tube_and_sphere_qvtk_NG](https://discourse.vtk.org/uploads/default/original/1X/23299096825a0c04e0061bf99daf2cb7c530d34a.png)

Code example:

```auto
#include <vtkSmartPointer.h>
#include <vtkConeSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkRenderWindow.h>
#include <vtkActor.h>
#include <vtkProperty.h>
#include <vtkRenderer.h>
#include <vtkGenericOpenGLRenderWindow.h>

#include <QVBoxLayout>
#include <QVTKOpenGLWidget.h>

#include "qvtk_tubes_spheres.h"
#include <qcoreapplication.h>

Widget::Widget(QWidget *parent) : QWidget(parent)
{
    qvtk = new QVTKOpenGLWidget(this);
    layout = new QVBoxLayout(this);
    layout->addWidget(qvtk);
    setLayout(layout);
    resize(300, 300);

    auto cone = vtkSmartPointer<vtkConeSource>::New();
    auto mapper = vtkSmartPointer<vtkPolyDataMapper>::New();
    auto actor = vtkSmartPointer<vtkActor>::New();
    auto ren = vtkSmartPointer<vtkRenderer>::New();
    auto renwin = vtkSmartPointer<vtkGenericOpenGLRenderWindow>::New();

    mapper->SetInputConnection(cone->GetOutputPort());
    actor->SetMapper(mapper);

    ///////////////////////////////////////////////////////////////////
    // Rendering Tubes and Spheres in VTK
    // https://blog.kitware.com/rendering-tubes-and-spheres-in-vtk/

    actor->GetProperty()->SetEdgeVisibility(1);
    actor->GetProperty()->SetEdgeColor(0.9, 0.9, 0.4);
    actor->GetProperty()->SetLineWidth(6);
    actor->GetProperty()->SetPointSize(12);
    actor->GetProperty()->SetRenderLinesAsTubes(1);
    actor->GetProperty()->SetRenderPointsAsSpheres(1);
    actor->GetProperty()->SetVertexVisibility(1);
    actor->GetProperty()->SetVertexColor(0.5, 1.0, 0.8);
    ///////////////////////////////////////////////////////////////////
    
    ren->AddActor(actor);
    renwin->AddRenderer(ren);

#if VTK_MINOR_VERSION < 90
    qvtk->SetRenderWindow(renwin);
    qvtk->GetRenderWindow()->Render();
#else
    qvtk->setRenderWindow(renwin);
    qvtk->renderWindow()->Render();
#endif   
}

```

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<div class="post-metadata">

### Author: ![AlopexH2O](https://discourse.vtk.org/user_avatar/discourse.vtk.org/alopexh2o/32/4715_2.png) [@AlopexH2O](https://discourse.vtk.org/u/AlopexH2O)
#### Post date: [February 18, 2022, 5:40am UTC](https://discourse.vtk.org/t/qvtkopenglwidget-vertices-disappear-when-renderpointsassphereson/1007/2 "2022-02-18T05:40:49Z")

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I encountered similar problems when using QVTKOpenGLNativeWidget, VTK9.0.3 and QT5.14.2 🙃 Expert for any solution.

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<div class="post-metadata">

### Author: ![blank.lu](https://discourse.vtk.org/user_avatar/discourse.vtk.org/blank.lu/32/5548_2.png) [@blank.lu](https://discourse.vtk.org/u/blank.lu)
#### Post date: [July 22, 2022, 3:04am UTC](https://discourse.vtk.org/t/qvtkopenglwidget-vertices-disappear-when-renderpointsassphereson/1007/3 "2022-07-22T03:04:16Z")

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// before initializing QApplication, set the default surface format.  
QSurfaceFormat::setDefaultFormat(QVTKOpenGLNativeWidget::defaultFormat());  
I do this, RenderPointsAsSpheresOn() is successful.