fails to compile with python3

[RadTekWeb]

As title says, fails when compiling freenect3.c:

[ 91%] Linking CXX executable ../../bin/freenect-cpp_pcview
[ 91%] Built target freenect-cpp_pcview
[ 92%] Building CXX object wrappers/cpp/CMakeFiles/freenect-cppview.dir/cppview.cpp.o
[ 94%] Linking CXX executable ../../bin/freenect-cppview
[ 94%] Built target freenect-cppview
[ 96%] Generating freenect3.c
Scanning dependencies of target cython3_freenect
[ 98%] Building C object wrappers/python/CMakeFiles/cython3_freenect.dir/freenect3.c.o
cc1: warning: /usr/bin/python3: not a directory
/home/username/libfreenect/build/wrappers/python/freenect3.c:4:10: fatal error: Python.h: No such file or directory
    4 | #include "Python.h"
      |          ^~~~~~~~~~
compilation terminated.
make[2]: *** [wrappers/python/CMakeFiles/cython3_freenect.dir/build.make:67: wrappers/python/CMakeFiles/cython3_freenect.dir/freenect3.c.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:743: wrappers/python/CMakeFiles/cython3_freenect.dir/all] Error 2
make: *** [Makefile:130: all] Error 2

I'm on mint 20, python3.8.5, cython3 0.29.14, cmake 3.16 if that matters, thanks

[piedar]

Have you installed the python3-dev package?

[RadTekWeb]

Have you installed the python3-dev package?

Yes, 3.8.2-0ubuntu2

Edit: if that helps I had to manually set path to cython3 because make was throwing

/bin/sh: 1: CYTHON_EXECUTABLE-NOTFOUND: not found
make[2]: *** [wrappers/python/CMakeFiles/cython3_freenect.dir/build.make:62: wrappers/python/freenect3.c] Error 127
make[1]: *** [CMakeFiles/Makefile2:742: wrappers/python/CMakeFiles/cython3_freenect.dir/all] Error 2
make: *** [Makefile:130: all] Error 2

I can't find where I made that change now but maybe I have to also manually attach those python libraries?

[piedar]

Is there any chance you have multiple python versions installed? For example I have 3.8 and 3.9 so I have to write

cmake .. -L -DBUILD_PYTHON3=ON -DPython3_EXACTVERSION=3.8

to make cmake use the correct version. Then it should say something like

-- Found Python3: /usr/bin/python3.8 (found suitable exact version "3.8.7") found components: Interpreter Development Development.Module Development.Embed

and cmake should set Python3_INCLUDE_DIRS properly.

[RadTekWeb]

That was it, thank you so much!