# VTK + QT in emscripten webassembly: opengl ERROR: unknown type name 'PFNGLPUSHDEBUGGROUPPROC'; did you mean 'PFNGLPUSHDEBUGGROUPKHRPROC'
**URL:** https://discourse.vtk.org/t/vtk-qt-in-emscripten-webassembly-opengl-error-unknown-type-name-pfnglpushdebuggroupproc-did-you-mean-pfnglpushdebuggroupkhrproc/12447
**Category:** Support
**Created:** [October 9, 2023, 8:17am UTC](https://discourse.vtk.org/t/vtk-qt-in-emscripten-webassembly-opengl-error-unknown-type-name-pfnglpushdebuggroupproc-did-you-mean-pfnglpushdebuggroupkhrproc/12447 "2023-10-09T08:17:30Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@cebugdev](https://discourse.vtk.org/u/cebugdev)
#### Post date: [October 9, 2023, 8:17am UTC](https://discourse.vtk.org/t/vtk-qt-in-emscripten-webassembly-opengl-error-unknown-type-name-pfnglpushdebuggroupproc-did-you-mean-pfnglpushdebuggroupkhrproc/12447/1 "2023-10-09T08:17:30Z")
Our previous developer left but he only gave a little information on how he built the project in QT, but we saw that it was built succesfuly as we have seen it runing as a web page (our desktop QT that is).
here is what I did:
1. I downloaded QT as an installer
2. After download, I ran the Maintenance tool, Went to add or remove components.
I Installed QT 6.5.0 and the platflorms
MinGW 11.2.0 64 bit
WebAssemby (single-threaded)
WebAssembly (multi-threaded)
I also downloaded under developer tools
MingW 11.2.0 64 bit
CMake 3.24.2
3. I also downloaded (apart from QT)
ninja 1.11
Emscripted 3.1.25
VTK 9.2.6
4. So I went ahead and follow instructions based from here [Qt for WebAssembly | Qt 6.5](https://doc.qt.io/qt-6/wasm.html)
I ran the configure with emscripten like the one bellow,
```auto
./emsdk install 3.1.25
./emsdk activate 3.1.25
configure.bat -qt-host-path C:\Qt\6.5.0\mingw_64 -no-warnings-are-errors -feature-opengles3 -device-option QT_EMSCRIPTEN_ASYNCIFY=1 -platform wasm-emscripten -prefix $PWD/qtbase
cmake –build .
```
All of the above is executed inside the source folder C:\Qt\6.5.0\Src
And I specify mingw\_64 as the host-path as it is the ONLY one that compiles properly.
1. Then I downloaded VTK and build like this
Everything builts ok without error. So I went to our project and started the build
```auto
emsdk activate 3.1.25
emsdk_env.bat
qmake.bat OurProject.pro
mingw32-make
```
qmake.bat is from C:\Qt\6.5.0\wasm\_singlethread\bin
while mingw32-make is from C:\Qt\Tools\mingw1120\_64\bin
Then I got these errors
```auto
In file included from Ui\VTKWidgets\MyQVTKOpenGLWindow.cpp:46:
In file included from ..\..\dependencies\VTK-9.2.6\include\vtk-9.2\vtk_glew.h:47:
..\..\dependencies\VTK-9.2.6\include\vtk-9.2\vtkglew/include/GL/glew.h:24591:17: error: unknown type name
'PFNGLPOPDEBUGGROUPPROC'; did you mean 'PFNGLPOPDEBUGGROUPKHRPROC'?
GLEW_FUN_EXPORT PFNGLPOPDEBUGGROUPPROC __glewPopDebugGroup;
^ ~~~~~~~~~~~~~~~~~~~~~
PFNGLPOPDEBUGGROUPKHRPROC
C:\Qt\6.5.0\wasm_singlethread\include\QtGui/qopengles2ext.h:155:28: note: 'PFNGLPOPDEBUGGROUPKHRPROC' declared here
typedef void (GL_APIENTRYP PFNGLPOPDEBUGGROUPKHRPROC) (void);
```
Im not sure what is happening here? I went to the file and PFNGLPUSHDEBUGGROUPPROC is indeed defined properly in vtk-9.2\vtkglew/include/GL/glew.h
maybe there is a conflict between OpenGL versions?
Maybe i misconfigured VTK for opengl? I am not sure what is happening here now.
Ive been stuck wth this for over 2 weeks, please help
---
### Author:  [@jaswantp](https://discourse.vtk.org/u/jaswantp)
#### Post date: [October 9, 2023, 12:32pm UTC](https://discourse.vtk.org/t/vtk-qt-in-emscripten-webassembly-opengl-error-unknown-type-name-pfnglpushdebuggroupproc-did-you-mean-pfnglpushdebuggroupkhrproc/12447/2 "2023-10-09T12:32:20Z")
Hello @cebugdev
What is the value of `VTK_OPENGL_USE_GLES` in your CMakeCache.txt?
---
### Author:  [@cebugdev](https://discourse.vtk.org/u/cebugdev)
#### Post date: [October 9, 2023, 3:06pm UTC](https://discourse.vtk.org/t/vtk-qt-in-emscripten-webassembly-opengl-error-unknown-type-name-pfnglpushdebuggroupproc-did-you-mean-pfnglpushdebuggroupkhrproc/12447/3 "2023-10-09T15:06:43Z")
> [@jaswantp](#):
>
> VTK\_OPENGL\_USE\_GLES
it is set to off in VTK CMakeCache.txt
//Use the OpenGL ES API
VTK\_OPENGL\_USE\_GLES:BOOL=OFF
Should it be ON or Off is the correct behaviour for webasm?
This is my cmake for VTK that I used
> emcmake cmake . -B C:\build-vtk-wasm -GNinja -DBUILD\_SHARED\_LIBS:BOOL=OFF -DCMAKE\_BUILD\_TYPE:STRING=Release -DVTK\_ENABLE\_LOGGING:BOOL=OFF -DVTK\_ENABLE\_WRAPPING:BOOL=OFF -DVTK\_MODULE\_ENABLE\_VTK\_hdf5:STRING=NO -DVTK\_MODULE\_ENABLE\_VTK\_RenderingContextOpenGL2:STRING=DONT\_WANT -DVTK\_MODULE\_ENABLE\_VTK\_RenderingLICOpenGL2:STRING=DONT\_WANT -DVTK\_MODULE\_ENABLE\_VTK\_RenderingCellGrid:STRING=NO -DVTK\_MODULE\_ENABLE\_VTK\_sqlite:STRING=NO -DCMAKE\_INSTALL\_PREFIX=C:\vtk-install
---
### Author:  [@jaswantp](https://discourse.vtk.org/u/jaswantp)
#### Post date: [October 9, 2023, 3:49pm UTC](https://discourse.vtk.org/t/vtk-qt-in-emscripten-webassembly-opengl-error-unknown-type-name-pfnglpushdebuggroupproc-did-you-mean-pfnglpushdebuggroupkhrproc/12447/4 "2023-10-09T15:49:43Z")
It should be on. Just add `-DVTK_OPENGL_USE_GLES=ON` to your cmake configure arguments.
---
### Author:  [@cebugdev](https://discourse.vtk.org/u/cebugdev)
#### Post date: [October 10, 2023, 8:42am UTC](https://discourse.vtk.org/t/vtk-qt-in-emscripten-webassembly-opengl-error-unknown-type-name-pfnglpushdebuggroupproc-did-you-mean-pfnglpushdebuggroupkhrproc/12447/5 "2023-10-10T08:42:46Z")
i think it worked, thank you, i now reach the final stages of the build which is linking.
but I am having problem, seems like freetype for VTK and QT had a clash
```auto
wasm-ld: error: duplicate symbol: ft_mem_realloc
>>> defined in ../../dependencies/VTK-9.2.6/lib\\libvtkfreetype-9.2.a(ftbase.c.o)
>>> defined in C:/Qt/6.5.0/wasm_singlethread/lib/libQt6BundledFreetype.a(ftbase.c.o)
wasm-ld: error: duplicate symbol: FT_GlyphLoader_CheckPoints
>>> defined in ../../dependencies/VTK-9.2.6/lib\\libvtkfreetype-9.2.a(ftbase.c.o)
>>> defined in C:/Qt/6.5.0/wasm_singlethread/lib/libQt6BundledFreetype.a(ftbase.c.o)
wasm-ld: error: duplicate symbol: FT_GlyphLoader_CheckSubGlyphs
>>> defined in ../../dependencies/VTK-9.2.6/lib\\libvtkfreetype-9.2.a(ftbase.c.o)
>>> defined in C:/Qt/6.5.0/wasm_singlethread/lib/libQt6BundledFreetype.a(ftbase.c.o)
```
How do I handle this?
---
### Author:  [@jaswantp](https://discourse.vtk.org/u/jaswantp)
#### Post date: [October 10, 2023, 2:31pm UTC](https://discourse.vtk.org/t/vtk-qt-in-emscripten-webassembly-opengl-error-unknown-type-name-pfnglpushdebuggroupproc-did-you-mean-pfnglpushdebuggroupkhrproc/12447/6 "2023-10-10T14:31:19Z")
Have you tried `-DVTK_MODULE_ENABLE_VTK_RenderingFreeType:STRING=DONT_WANT`? @ben.boeckel may have some ideas.
---
### Author:  [@ben.boeckel](https://discourse.vtk.org/u/ben.boeckel)
#### Post date: [October 10, 2023, 2:38pm UTC](https://discourse.vtk.org/t/vtk-qt-in-emscripten-webassembly-opengl-error-unknown-type-name-pfnglpushdebuggroupproc-did-you-mean-pfnglpushdebuggroupkhrproc/12447/7 "2023-10-10T14:38:06Z")
It looks like 9.2.6 has some unmangled symbols. Can you please test 9.3.0.rc1 so we can fix it if it needs to be?
---
### Author:  [@cebugdev](https://discourse.vtk.org/u/cebugdev)
#### Post date: [October 11, 2023, 2:06am UTC](https://discourse.vtk.org/t/vtk-qt-in-emscripten-webassembly-opengl-error-unknown-type-name-pfnglpushdebuggroupproc-did-you-mean-pfnglpushdebuggroupkhrproc/12447/8 "2023-10-11T02:06:49Z")
Tried this still getting the errors
```auto
wasm-ld: error: duplicate symbol: FT_GlyphLoader_CreateExtra
>>> defined in ../../dependencies/VTK-9.2.6/lib\\libvtkfreetype-9.2.a(ftbase.c.o)
>>> defined in C:/Qt/6.5.0/wasm_singlethread/lib/libQt6BundledFreetype.a(ftbase.c.o)
wasm-ld: error: duplicate symbol: ft_mem_realloc
>>> defined in ../../dependencies/VTK-9.2.6/lib\\libvtkfreetype-9.2.a(ftbase.c.o)
>>> defined in C:/Qt/6.5.0/wasm_singlethread/lib/libQt6BundledFreetype.a(ftbase.c.o)
```
will try a different versions as suggested by Ben
Update: Tried a different version with 9.3 but same error ☹
---
### Author:  [@ben.boeckel](https://discourse.vtk.org/u/ben.boeckel)
#### Post date: [October 11, 2023, 4:54pm UTC](https://discourse.vtk.org/t/vtk-qt-in-emscripten-webassembly-opengl-error-unknown-type-name-pfnglpushdebuggroupproc-did-you-mean-pfnglpushdebuggroupkhrproc/12447/9 "2023-10-11T16:54:50Z")
Ok, it looks like we are missing some symbol manglings, at least on Windows. Can you please file an issue about this?
---
### Author:  [@cebugdev](https://discourse.vtk.org/u/cebugdev)
#### Post date: [October 12, 2023, 12:22am UTC](https://discourse.vtk.org/t/vtk-qt-in-emscripten-webassembly-opengl-error-unknown-type-name-pfnglpushdebuggroupproc-did-you-mean-pfnglpushdebuggroupkhrproc/12447/10 "2023-10-12T00:22:44Z")
filed an issue in gitlab here: [https://gitlab.kitware.com/vtk/vtk/-/issues/19129](https://gitlab.kitware.com/vtk/vtk/-/issues/19129)