# I encountered an error when using QT and VTK

**URL:** https://discourse.vtk.org/t/i-encountered-an-error-when-using-qt-and-vtk/6559
**Category:** Support
**Created:** [September 6, 2021, 3:26am UTC](https://discourse.vtk.org/t/i-encountered-an-error-when-using-qt-and-vtk/6559 "2021-09-06T03:26:26Z")
**Posts on this page:** 7
**Page:** 1

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### Author: ![loufear](https://discourse.vtk.org/user_avatar/discourse.vtk.org/loufear/32/3150_2.png) [@loufear](https://discourse.vtk.org/u/loufear)
#### Post date: [September 6, 2021, 3:26am UTC](https://discourse.vtk.org/t/i-encountered-an-error-when-using-qt-and-vtk/6559/1 "2021-09-06T03:26:27Z")

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```auto
ERROR: In D:\VTK-8.2.0\Rendering\OpenGL2\vtkTextureObject.cxx, line 1991
vtkTextureObject (000001F475680680): failed at glCopyTexImage2D 33191 1 OpenGL errors detected
  0 : (1282) Invalid operation

```

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<div class="post-metadata">

### Author: ![mwestphal](https://discourse.vtk.org/user_avatar/discourse.vtk.org/mwestphal/32/19_2.png) [@mwestphal](https://discourse.vtk.org/u/mwestphal)
#### Post date: [September 6, 2021, 6:09am UTC](https://discourse.vtk.org/t/i-encountered-an-error-when-using-qt-and-vtk/6559/2 "2021-09-06T06:09:34Z")

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Please share steps to reproduce

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<div class="post-metadata">

### Author: ![loufear](https://discourse.vtk.org/user_avatar/discourse.vtk.org/loufear/32/3150_2.png) [@loufear](https://discourse.vtk.org/u/loufear)
#### Post date: [September 6, 2021, 6:12am UTC](https://discourse.vtk.org/t/i-encountered-an-error-when-using-qt-and-vtk/6559/3 "2021-09-06T06:12:57Z")

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```
m_vtkWidget = new QVTKOpenGLNativeWidget(ui->renderWidget);

vtkSmartPointer<vtkRenderWindowInteractor>iren = vtkSmartPointer<vtkRenderWindowInteractor>::New();
iren->SetStillUpdateRate(0.016);

vtkSmartPointer<vtkGenericOpenGLRenderWindow> renderWindow = vtkSmartPointer<vtkGenericOpenGLRenderWindow>::New();
//renderWindow->SetWindowName("RenderWindow");
renderWindow->SetDesiredUpdateRate(0.016);
renderWindow->SetInteractor(iren);

m_vtkWidget->SetRenderWindow(renderWindow);

QString DirName = QFileDialog::getExistingDirectory(this,tr("select file"),"D:",0);

vtkSmartPointer<vtkDICOMImageReader>dicomImagereader = vtkSmartPointer<vtkDICOMImageReader>::New();
dicomImagereader->SetDirectoryName(DirName.toStdString().c_str());
//dicomImagereader->SetDirectoryName("pig");
dicomImagereader->Update();

vtkSmartPointer<vtkGPUVolumeRayCastMapper>volumeMapper = vtkSmartPointer<vtkGPUVolumeRayCastMapper>::New();
volumeMapper->SetBlendMode(vtkVolumeMapper::COMPOSITE_BLEND);
volumeMapper->SetInputConnection(dicomImagereader->GetOutputPort());
volumeMapper->SetSampleDistance(volumeMapper->GetSampleDistance() * 0.9); //光线步长
volumeMapper->SetAutoAdjustSampleDistances(0);
//volumeMapper->SetCropping(1);//开启Cropping功能
//volumeMapper->SetCroppingRegionPlanes(origin[0] + dims[0] * spacing[0] / 3, origin[0] + dims[0] * spacing[0] / 3 * 2, origin[1] + dims[1] * spacing[1] / 3, origin[1] + dims[1] * spacing[1] / 3 * 2, origin[2] + dims[2] * spacing[2] / 3, origin[2] + dims[2] * spacing[2] / 3 * 2);
//volumeMapper->SetCroppingRegionFlagsToCross();

volume = vtkVolume::New();
volume->SetMapper(volumeMapper);
volume->SetProperty(VpParser("CTAAA2.vp"));

vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();
renderer->AddVolume(volume);
renderer->SetBackground(0.5,0.5,0.5);

m_vtkWidget->GetRenderWindow()->AddRenderer(renderer);
m_vtkWidget->show();
```

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<div class="post-metadata">

### Author: ![loufear](https://discourse.vtk.org/user_avatar/discourse.vtk.org/loufear/32/3150_2.png) [@loufear](https://discourse.vtk.org/u/loufear)
#### Post date: [September 6, 2021, 6:15am UTC](https://discourse.vtk.org/t/i-encountered-an-error-when-using-qt-and-vtk/6559/4 "2021-09-06T06:15:21Z")

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I changed from -\>render to show(), error disappeared, but window does nothing

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<div class="post-metadata">

### Author: ![mwestphal](https://discourse.vtk.org/user_avatar/discourse.vtk.org/mwestphal/32/19_2.png) [@mwestphal](https://discourse.vtk.org/u/mwestphal)
#### Post date: [September 6, 2021, 7:09am UTC](https://discourse.vtk.org/t/i-encountered-an-error-when-using-qt-and-vtk/6559/5 "2021-09-06T07:09:29Z")

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> [@loufear](#):
>
> `QVTKOpenGLNativeWidget`

Here is an example usage:  
[https://kitware.github.io/vtk-examples/site/Cxx/Qt/EventQtSlotConnect/](https://kitware.github.io/vtk-examples/site/Cxx/Qt/EventQtSlotConnect/)

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<div class="post-metadata">

### Author: ![loufear](https://discourse.vtk.org/user_avatar/discourse.vtk.org/loufear/32/3150_2.png) [@loufear](https://discourse.vtk.org/u/loufear)
#### Post date: [September 6, 2021, 7:48am UTC](https://discourse.vtk.org/t/i-encountered-an-error-when-using-qt-and-vtk/6559/6 "2021-09-06T07:48:47Z")

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m\_vtkWidget-\>GetRenderWindow()-\>Render(); \* this code will still report the error

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<div class="post-metadata">

### Author: ![loufear](https://discourse.vtk.org/user_avatar/discourse.vtk.org/loufear/32/3150_2.png) [@loufear](https://discourse.vtk.org/u/loufear)
#### Post date: [September 6, 2021, 8:01am UTC](https://discourse.vtk.org/t/i-encountered-an-error-when-using-qt-and-vtk/6559/7 "2021-09-06T08:01:38Z")

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> [@vtkGPUVolumeRayCastMapper and Qt (bug?)](https://discourse.vtk.org/t/vtkgpuvolumeraycastmapper-and-qt-bug/1640):
>
> Hello everyone, I’m working on Windows 10 1903, with Visual Studio 2017 (19.16.27031.1), VTK 8.2 and Qt 5.12.4. My graphic cards is a RTX 2080 Max-Q and the Nvidia driver version is 431.70. I try to use vtkGPUVolumeRayCastMapper inside a Qt window. I test the example MedicalDemo4 by replacing vtkFixedPointVolumeRayCastMapper by vtkGPUVolumeRayCastMapper and it’s working great inside a VTK Window. After that, I used the RenderWindowNoUiFile example and add the vtkVolume to the renderer. But…

- I think his situation is the same as mine