# Can't use vtkExternalOpenGLRenderer - vtkRenderingExternalModule.h is missing
**URL:** https://discourse.vtk.org/t/cant-use-vtkexternalopenglrenderer-vtkrenderingexternalmodule-h-is-missing/14790
**Category:** Support
**Created:** [October 30, 2024, 3:22pm UTC](https://discourse.vtk.org/t/cant-use-vtkexternalopenglrenderer-vtkrenderingexternalmodule-h-is-missing/14790 "2024-10-30T15:22:22Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Seb-surgar](https://discourse.vtk.org/u/Seb-surgar)
#### Post date: [October 30, 2024, 3:22pm UTC](https://discourse.vtk.org/t/cant-use-vtkexternalopenglrenderer-vtkrenderingexternalmodule-h-is-missing/14790/1 "2024-10-30T15:22:23Z")
Hello,
I am on ubuntu and I can’t use the vtkExternalOpenGLRenderer (or other vtkExternal… class) because the file vtkRenderingExternalModule.h is missing.
Is this file supposed to be automatically generated during build ? Or can you tell me where to find it ?
I have recompiled the VTK lib from source with no problem but this file is always missing.
Thanks in advance
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### Author:  [@mwestphal](https://discourse.vtk.org/u/mwestphal)
#### Post date: [October 30, 2024, 3:37pm UTC](https://discourse.vtk.org/t/cant-use-vtkexternalopenglrenderer-vtkrenderingexternalmodule-h-is-missing/14790/2 "2024-10-30T15:37:35Z")
you need to enable the following cmake variable:
`VTK_MODULE_ENABLE_VTK_RenderingExternal`
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### Author:  [@Seb-surgar](https://discourse.vtk.org/u/Seb-surgar)
#### Post date: [October 31, 2024, 9:05am UTC](https://discourse.vtk.org/t/cant-use-vtkexternalopenglrenderer-vtkrenderingexternalmodule-h-is-missing/14790/3 "2024-10-31T09:05:01Z")
Ok, it’s working.
Thanks !