[vtk-developers] Using VTK master fails on Ubuntu 18.04 due to missing FindPython3.cmake

[Elvis Stansvik]

Trying to build a project against VTK master on Ubuntu 18.04, I get:

CMake Error at /home/estan/orexplore/VTK-inst/lib/cmake/vtk-8.90/VTK-vtk-module-find-packages.cmake:475
(find_package):
  By not providing "FindPython3.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "Python3", but
  CMake did not find one.

  Could not find a package configuration file provided by "Python3"
  (requested version 3.6) with any of the following names:

    Python3Config.cmake
    python3-config.cmake

  Add the installation prefix of "Python3" to CMAKE_PREFIX_PATH or set
  "Python3_DIR" to a directory containing one of the above files.  If
  "Python3" provides a separate development package or SDK, be sure it has
  been installed.
Call Stack (most recent call first):
  /home/estan/orexplore/VTK-inst/lib/cmake/vtk-8.90/vtk-config.cmake:92
(include)
  CMakeLists.txt:5 (find_package)


-- Configuring incomplete, errors occurred!

The new FindPython3.cmake was added in CMake 3.12, but Ubuntu 18.04
has CMake 3.10.2.

I know building VTK itself is possible with CMake 3.8+ (this VTK was
built on the same machine).

Should perhaps the installed VTK-vtk-module-find-packages.cmake be
updated so that it can work with the older Python-finding stuff as
well?

Elvis