[pdal] Build pdal with python 3

[FE]

Hi,
 
I've managed to build pdal 1.1.0 on OS X using cmake-gui and makefiles. It was build with python 2 by default. Python modules installed via 'pip install pdal' work (after several pathes in the libraries have been corrected manually with 'install_name_tool').
 
However, since I work with python 3 I would like to build pdal with python 3 (it seems impossible to install pdal python modules in a python 3 environment having pdal build with python 2 -> causes various error messages).
Would anybody like to explain how to build pdal with python 3 on OS X? I am not very deep into these techniques and did not manage until now.
 
How can I tell cmake to use python 3? It is unclear to me which python is used by cmake.
I have three pythons on the computer. The system python is python 2, Homebrew python is python 2 (and python 3 could be installed easily), finally I use Anaconda with a python 3 environment.
Does cmake only requires the python include directories? How to tell cmake which python to use?
 
Thank you in advance!