How to use Eigen inside VTK

Hi, I’m trying to use Eigen for some geometry computing, but I don’t know how to use the VTK third-party module and how to include the Eigen header.
For now, In CMakeLists, I put vtkeigen in the find_package, and include vtk_eigen.h. But still quite confused about what’s next. Please share some advice about how to use Eigen. Thank you in advance :smiley:

update, I got the solution, just build vtk with -DVTK_MODULE_USE_EXTERNAL_vtkeigen=ON