I am trying to link an existing software to VTK9.1, and keep getting a compile-time error “vtkXMLPUnstructuredGridWriter.h not found”. It is indeed missing from the …/include directory, although vtkXMLPUnstructuredGridReader.h is there.
I built VTK with USE_MPI=ON and VTK_GROUP_ENABLE_MPI=YES, but it does not help.
The MPI group doesn’t interact with the VTK::IOParallelXML module, so that makes sense. Please make sure that the module is available. Note that the reader is in VTK::IOXML, so the presence of the reader does not imply the availability of the writer.