Add VTK sample function and related test

cmake/modules/FindDEAL_II_VTK.cmake

@@ -1,6 +1,6 @@
 ## ---------------------------------------------------------------------
 ##
-## Copyright (C) 2022 by the deal.II authors
+## Copyright (C) 2023 by the deal.II authors
 ##
 ## This file is part of the deal.II library.
 ##
@@ -39,43 +39,27 @@ if(VTK_FOUND)
   set(VTK_MINOR_VERSION "${VTK_MINOR_VERSION}")
 
   set(VTK_INCLUDE_DIR
-      ${VTK_PREFIX_PATH}/include/vtk-${VTK_MAJOR_VERSION}.${VTK_MINOR_VERSION})
+    ${VTK_PREFIX_PATH}/include/vtk-${VTK_MAJOR_VERSION}.${VTK_MINOR_VERSION})
 
-  #
-  # We'd like to have the full library names but the VTK package only
-  # exports a list with namespace-qualified names, e.g. VTK::CommonCore.
-  # So we check again for every lib and store the full path:
-  #
-  set(_libraries "")
+  # Try to find full paths from targets contained in VTK_LIBRARIES.
+  set(_libraries)
+  foreach(_library ${VTK_LIBRARIES})
+    if(NOT ${_library} MATCHES "Python"
+	AND NOT ${_library} MATCHES "MPI4Py")
+      get_target_property(_configurations ${_library} IMPORTED_CONFIGURATIONS)
 
-  foreach(_component ${VTK_AVAILABLE_COMPONENTS})
-    deal_ii_find_library(VTK_LIBRARY_${_component}
-      NAMES libvtk${_component}-${VTK_VERSION_MAJOR}.${VTK_VERSION_MINOR}.so
-      HINTS ${VTK_PREFIX_PATH}/lib
-      NO_DEFAULT_PATH
-      NO_CMAKE_ENVIRONMENT_PATH
-      NO_CMAKE_PATH
-      NO_SYSTEM_ENVIRONMENT_PATH
-      NO_CMAKE_SYSTEM_PATH
-      NO_CMAKE_FIND_ROOT_PATH
-    )
-
-    if (NOT "${VTK_LIBRARY_${_component}}" MATCHES "-NOTFOUND")
-      list(APPEND _libraries VTK_LIBRARY_${_component})
-    else()
-      # VTK_AVAILABLE_COMPONENTS contains also header-only modules.
-      # If the library has not been found, check if corresponding
-      # headers exist.
-      if (NOT EXISTS "${VTK_INCLUDE_DIR}/${_component}" AND
-          NOT EXISTS "${VTK_INCLUDE_DIR}/vtk_${_component}.h")
-        message(FATAL_ERROR "VTK: component ${_component} not found.")
+      if(_configurations)
+	foreach(_configuration ${_configurations})
+          get_target_property(_imported_location ${_library} IMPORTED_LOCATION_${_configuration})
+          list(APPEND _libraries ${_imported_location})
+	endforeach()
       endif()
     endif()
   endforeach()
 endif()
 
 process_feature(VTK
-  LIBRARIES REQUIRED ${_libraries}
+  LIBRARIES REQUIRED _libraries
   INCLUDE_DIRS REQUIRED VTK_INCLUDE_DIR
-  CLEAR VTK_INCLUDE_DIR VTK_LIBRARIES ${_libraries}
+  CLEAR VTK_INCLUDE_DIR VTK_LIBRARIES _libraries
 )

include/deal.II/vtk/utilities.h

@@ -0,0 +1,81 @@
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2023 by the deal.II authors
+//
+// This file is part of the deal.II library.
+//
+// The deal.II library is free software; you can use it, redistribute
+// it, and/or modify it under the terms of the GNU Lesser General
+// Public License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+// The full text of the license can be found in the file LICENSE.md at
+// the top level directory of deal.II.
+//
+// ---------------------------------------------------------------------
+
+#ifndef dealii_vtk_utilities_h
+#define dealii_vtk_utilities_h
+
+#include <deal.II/base/config.h>
+
+#include <deal.II/base/exceptions.h>
+
+#ifdef DEAL_II_WITH_VTK
+
+#  include <vtkDoubleArray.h>
+
+DEAL_II_NAMESPACE_OPEN
+
+/**
+ * Interface to the Visualization Toolkit (VTK).
+ *
+ * VTK is an open-source, freely available software system for 3D computer
+ * graphics, modeling, image processing, volume rendering, scientific
+ * visualization, and 2D plotting.
+
+ * It supports a wide variety of visualization algorithms and advanced
+ * modeling techniques, and it takes advantage of both threaded and distributed
+ * memory parallel processing for speed and scalability, respectively.
+ *
+ * You can learn more about the VTK library at https://vtk.org/
+ */
+namespace VTKWrappers
+{
+  /**
+   * Convert from a deal.II Point to a VTK double array.
+   *
+   * @tparam dim Dimension of the point
+   * @param [in] p An input deal.II Point<dim>
+   * @return A VTK smart pointer to the data array.
+   */
+  template <int dim>
+  inline vtkSmartPointer<vtkDoubleArray>
+  dealii_point_to_vtk_array(const dealii::Point<dim> &p);
+
+#  ifndef DOXYGEN
+  // Template implementations
+
+  template <int dim>
+  inline vtkSmartPointer<vtkDoubleArray>
+  dealii_point_to_vtk_array(const dealii::Point<dim> &p)
+  {
+    vtkSmartPointer<vtkDoubleArray> p_vtk =
+      vtkSmartPointer<vtkDoubleArray>::New();
+
+    p_vtk->SetNumberOfComponents(dim);
+    p_vtk->SetNumberOfTuples(1);
+
+    for (int d = 0; d < dim; ++d)
+      p_vtk->FillComponent(d, p[d]);
+
+    return p_vtk;
+  }
+
+#  endif
+
+} // namespace VTKWrappers
+
+DEAL_II_NAMESPACE_CLOSE
+
+#endif
+#endif

tests/vtk/CMakeLists.txt

@@ -0,0 +1,6 @@
+cmake_minimum_required(VERSION 3.13.4)
+include(../setup_testsubproject.cmake)
+project(testsuite CXX)
+if(DEAL_II_WITH_VTK)
+  deal_ii_pickup_tests()
+endif()

tests/vtk/vtk_01.cc

@@ -0,0 +1,39 @@
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2023 by the deal.II authors
+//
+// This file is part of the deal.II library.
+//
+// The deal.II library is free software; you can use it, redistribute
+// it, and/or modify it under the terms of the GNU Lesser General
+// Public License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+// The full text of the license can be found in the file LICENSE.md at
+// the top level directory of deal.II.
+//
+// ---------------------------------------------------------------------
+
+// Test conversion from deal.II Point to VTK double array
+
+#include <deal.II/base/point.h>
+
+#include <deal.II/vtk/utilities.h>
+
+#include "../tests.h"
+
+int
+main()
+{
+  initlog();
+
+  // Test conversion from deal.II Point to VTK array.
+  {
+    const Point<3> point_dealii(1.0, 2.0, 3.0);
+    const auto point_vtk = VTKWrappers::dealii_point_to_vtk_array(point_dealii);
+    deallog << "VTK Point: " << point_vtk->GetComponent(0, 0) << ", "
+            << point_vtk->GetComponent(0, 1) << ", "
+            << point_vtk->GetComponent(0, 2) << std::endl;
+  }
+
+  return 0;
+}

tests/vtk/vtk_01.output

@@ -0,0 +1,2 @@
+
+DEAL::VTK Point: 1.00000, 2.00000, 3.00000