# framebuffer has mismatched attachments error when using vtkSobelGradientMagnitudePass and resizing window

**URL:** https://discourse.vtk.org/t/framebuffer-has-mismatched-attachments-error-when-using-vtksobelgradientmagnitudepass-and-resizing-window/4073
**Category:** Support
**Created:** [August 26, 2020, 7:05am UTC](https://discourse.vtk.org/t/framebuffer-has-mismatched-attachments-error-when-using-vtksobelgradientmagnitudepass-and-resizing-window/4073 "2020-08-26T07:05:10Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![rdbrn](https://discourse.vtk.org/user_avatar/discourse.vtk.org/rdbrn/32/5627_2.png) [@rdbrn](https://discourse.vtk.org/u/rdbrn)
#### Post date: [August 26, 2020, 7:05am UTC](https://discourse.vtk.org/t/framebuffer-has-mismatched-attachments-error-when-using-vtksobelgradientmagnitudepass-and-resizing-window/4073/1 "2020-08-26T07:05:10Z")

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I’m playing a bit with a vtkSobelGradientMagnitudePass pass using python and vtk 9.0.1 on Windows 10.

 ![afbeelding](https://discourse.vtk.org/uploads/default/original/2X/6/6d977540d97238c9c0f449d16a3c2bbb8b8013bb.png)

When I resize my window I get the following error:  
“ERROR: In …\Rendering\OpenGL2\vtkOpenGLFramebufferObject.cxx, line 523  
vtkOpenGLFramebufferObject (000001B3DB82E720): The framebuffer has mismatched attachments.”

Is this a bug or am I doing something wrong? I must say I’m having quite a hard time figuring out how to set up all the passes correctly.

```python
#!/usr/bin/env python

import vtk

def main():
    colors = vtk.vtkNamedColors()

    # Create a rendering window and renderer.
    ren = vtk.vtkRenderer()
    renWin = vtk.vtkRenderWindow()
    renWin.SetWindowName("Cube")
    renWin.AddRenderer(ren)

    # Create a renderwindowinteractor.
    iren = vtk.vtkRenderWindowInteractor()
    iren.SetRenderWindow(renWin)

    # Create cube.
    cube = vtk.vtkCubeSource()
    cube.SetXLength(5)
    cube.SetYLength(5)
    cube.SetZLength(5)
    cube.Update()

    # mapper
    cubeMapper = vtk.vtkPolyDataMapper()
    cubeMapper.SetInputData(cube.GetOutput())

    # Actor.
    cubeActor = vtk.vtkActor()
    cubeActor.SetMapper(cubeMapper)
    cubeActor.GetProperty().SetColor(colors.GetColor3d("Silver"))

    # Assign actor to the renderer.
    ren.AddActor(cubeActor)

    # Create cube.
    cube = vtk.vtkCubeSource()
    cube.SetXLength(2)
    cube.SetYLength(2)
    cube.SetZLength(2)
    cube.Update()

    # mapper
    cubeMapper = vtk.vtkPolyDataMapper()
    cubeMapper.SetInputData(cube.GetOutput())

    # Actor.
    cubeActor = vtk.vtkActor()
    cubeActor.SetMapper(cubeMapper)
    cubeActor.SetPosition(3.2,0,0)
    cubeActor.GetProperty().SetColor(colors.GetColor3d("Silver"))

    # Assign actor to the renderer.
    ren.AddActor(cubeActor)

    # And a sphere
    # Create cube.
    cube = vtk.vtkSphereSource()
    cube.SetRadius(2)
    cube.Update()

    # mapper
    cubeMapper = vtk.vtkPolyDataMapper()
    cubeMapper.SetInputData(cube.GetOutput())

    # Actor.
    cubeActor = vtk.vtkActor()
    cubeActor.SetMapper(cubeMapper)
    cubeActor.SetPosition(0,3.2, 0)
    cubeActor.GetProperty().SetColor(colors.GetColor3d("Silver"))

    # Assign actor to the renderer.
    ren.AddActor(cubeActor)

    ren.ResetCamera()
    ren.GetActiveCamera().Azimuth(30)
    ren.GetActiveCamera().Elevation(30)
    ren.ResetCameraClippingRange()
    ren.SetBackground(colors.GetColor3d("Blue"))

    # Add vtkSobelGradientMagnitudePass

    basicPasses = vtk.vtkRenderStepsPass()

    cameraPass = vtk.vtkCameraPass()
    cameraPass.SetDelegatePass(basicPasses)

    sobel = vtk.vtkSobelGradientMagnitudePass()
    sobel.SetDelegatePass(cameraPass)

    ren.SetPass(sobel)

    # Enable user interface interactor.
    iren.Initialize()
    renWin.Render()

    iren.Start()

if __name__ == " __main__":
    main()

```

---

<div class="post-metadata">

### Author: ![Lfx\_Paul](https://discourse.vtk.org/user_avatar/discourse.vtk.org/lfx_paul/32/2097_2.png) [@Lfx\_Paul](https://discourse.vtk.org/u/Lfx_Paul)
#### Post date: [August 26, 2020, 8:56am UTC](https://discourse.vtk.org/t/framebuffer-has-mismatched-attachments-error-when-using-vtksobelgradientmagnitudepass-and-resizing-window/4073/2 "2020-08-26T08:56:17Z")

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Hi Ruben,  
Good catch ! I opened an issue in VTK and the fix is going to be merged 🙂

[Here is the merge request](https://gitlab.kitware.com/vtk/vtk/-/merge_requests/7183)