[Interest] Trouble compiling qt3d for qt6 on windows 10

Paul Lemire paul.lemire at kdab.com
Tue Feb 16 14:22:28 CET 2021

On 2/16/21 1:33 PM, Daniel Patel wrote:
> Thanks a lot for the reply Paul, it was useful as always.
> Copying the files made the qt3d examples work!
> I realized that the compile error showed up because qt6 itself was 
> only compiled in debug mode.
> With the appropriate flag to the configure script, qt6 now compiles 
> both in debug and in release.
> However, now when compiling qt3d I ran into the error : "Could not 
> find feature qt3d-simd-avx2" (I already configured and compiled qt6 
> with -avx2 flag)
> I am just not able to tell/configure qt3d to use avx2 instead of sse2. 
> Currently "qmake .." returns:
>   Use SSE2 instructions .................. yes
>   Use AVX2 instructions .................. no
> After running configure for the qt6 build I got this text as output:
> "To configure and build other Qt modules, you can use the following 
> convenience script:
> C:/Qt/Qt-6.1/bin/qt-configure-module.bat"
> So i did a "c:\Qt\Qt-6.1\bin\qt-configure-module.bat 
> qt3d-everywhere-src-6.0.0 --qt3d-simd=avx2"   but that failed with  
> "Unknown command line option '--qt3d-simd=avx2'"  (I also tried 
> -avx2-qt3d-simd and -qt3d-simd-avx2)
> Anyone knows how to set configure flags for qt3d before compiling it?

What about -qt3d-simd avx2 (just a space)? That's what I use when 
compiling on linux with qmake. For Qt 6, I've switched to cmake though, 
option to use is -DFEATURE_qt3d_simd_avx2=ON on the cmake command line.

That being said, the avx2 option for Qt 3D essentially only yields 
better performance when we multiply matrices internally. The sse2 option 
is not much slower, a lot faster than relying on QMatrix4x4 (though this 
might have changed in Qt6, haven't checked).

> On a side note I also was not able to get qt6 configure script to 
> detect zlib libraries even though I set appropriate environment 
> variables and sent in paths using both -D option as well as -I and -L 
> option.
> man. 15. feb. 2021 kl. 11:47 skrev Paul Lemire <paul.lemire at kdab.com 
> <mailto:paul.lemire at kdab.com>>:
>     I can't really help about the compile issues. But I should be able
>     to help regarding the plugin error.
>     You likely need to copy a few more things from the qt3d build dir
>     to your Qt install dir:
>     qt3d_build_dir/qml/Qt3D into Qt_Install_Dir/qml/
>     qt3d_build_dir/qml/QtQuick/* into Qt_Install_Dir/qml/QtQuick/
>     qt3d_build_dir/plugins/* into Qt_Install_Dir/plugins/
>     (the plugins dir contains a renderers folder which contains the
>     Qt3D render plugins)
>     I hope that helps,
>     Paul
>     On 2/15/21 11:03 AM, Daniel Patel wrote:
>>     I have compiled qt6.1 from source which works and now I am trying
>>     to compile qt3d also from source by downloading from
>>     https://download.qt.io/official_releases/additional_libraries/qt3d/6.0/6.0.0/
>>     <https://download.qt.io/official_releases/additional_libraries/qt3d/6.0/6.0.0/>
>>     and following the qmake instructions from:
>>     https://www.kdab.com/getting-your-3d-ready-for-qt-6/
>>     <https://www.kdab.com/getting-your-3d-ready-for-qt-6/>
>>     I first tried to download and compile qt3d-everywhere-src-6.0.1
>>     but got an error about missing zlib.h. Instead of trying to fix
>>     this I quickly instead tried with qt3d-everywhere-src-6.0.0 and
>>     this compiled fine.
>>     However it only compiled debug dlls and not release dlls. I tried
>>     to do nmake all and nmake release but the latter gave the error
>>     "NMAKE : fatal error U1073: don't know how to make
>>     'C:\qtsrc\qt61\qt5\qtbase\lib\Qt6Gui.lib'"
>>     I then decided to try out the debug build. First I noticed that
>>     the qt3d dlls didnt seem to have been copied over to the correct
>>     folder when I did nmake install. So I copied them over manually
>>     and then started basicshapes-cpp.exe, but this showed the runtime
>>     error: Unable to find renderer plugin for opengl.
>>     Any hints for what to do?
>>     Best
>>     Daniel
>>     _______________________________________________
>>     Interest mailing list
>>     Interest at qt-project.org  <mailto:Interest at qt-project.org>
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>     -- 
>     Paul Lemire |paul.lemire at kdab.com  <mailto:paul.lemire at kdab.com>  | Senior Software Engineer
>     KDAB (France) S.A.S., a KDAB Group company
>     Tel: France +33 (0)4 90 84 08 53,http://www.kdab.fr  <http://www.kdab.fr>
>     KDAB - The Qt, C++ and OpenGL Experts
Paul Lemire | paul.lemire at kdab.com | Senior Software Engineer
KDAB (France) S.A.S., a KDAB Group company
Tel: France +33 (0)4 90 84 08 53, http://www.kdab.fr
KDAB - The Qt, C++ and OpenGL Experts

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