Improvement: Simplify VTK linking logic.

CMakeLists.txt

@@ -19,8 +19,6 @@ project(
   VERSION "${T8PROJECT_VERSION_MAJOR}.${T8PROJECT_VERSION_MINOR}.${T8PROJECT_VERSION_PATCH}"
 )
 
-option( T8PROJECT_ENABLE_VTK "Link against VTK. Must be used if t8code is linked against VTK." OFF )
-
 #
 # Enable "make test" to run all the tests
 #
@@ -37,19 +35,13 @@ set(CMAKE_CXX_COMPILER mpicxx)
 #  -DSC_DIR=PATH,
 find_package ( T8CODE REQUIRED)
 
-#
-# Find VTK library.
-# If t8code is linked against VTK then t8project should link against it as well.
-#
-if( T8PROJECT_ENABLE_VTK )
-    find_package( VTK REQUIRED COMPONENTS
-        IOXML CommonExecutionModel CommonDataModel
-        IOGeometry IOXMLParser IOParallelXML IOPLY
-        ParallelMPI FiltersCore vtksys CommonCore zlib IOLegacy)
-    if(VTK_FOUND)
-        message("Found VTK")
-    endif (VTK_FOUND)
-endif( T8PROJECT_ENABLE_VTK )
+# if t8code is linked against VTK, this project will
+# automatically detect it and link against VTK as well.
+# We set T8PROJECT_ENABLE_VTK to 1 in order to define our own VTK dependent macros in src/CMakeLists.txt
+if (T8CODE_ENABLE_VTK)
+    message ("t8code links against VTK with version ${T8CODE_VTK_VERSION_USED}")
+    set (T8PROJECT_ENABLE_VTK "1")
+endif ()
 
 # Recurse into the "test" subdirectory. This does not actually
 # cause another cmake executable to run. The same process will walk through

src/CMakeLists.txt

@@ -22,11 +22,16 @@ install( FILES
 
 # VTK dependent settings.
 if( T8PROJECT_ENABLE_VTK )
-    # Define T8PROJECT_VTK_MAJOR/MINOR_VERSION to true, such that get defined in t8project_vtk_linkage.hxx
-    set ( T8PROJECT_VTK_MAJOR_VERSION 1 )
-    set ( T8PROJECT_VTK_MINOR_VERSION 1 )
+    set ( T8PROJECT_VTK_VERSION_USED "${VTK_MAJOR_VERSION}.${VTK_MINOR_VERSION}" )
+    if (NOT ${T8PROJECT_VTK_VERSION_USED} STREQUAL ${T8CODE_VTK_VERSION_USED})
+        message (FATAL_ERROR "VTK version mismatch. t8code uses ${T8CODE_VTK_VERSION_USED} and this project uses ${T8PROJECT_VTK_VERSION_USED}.")
+    endif ()
     # Set CMake variables for lib target
-    target_compile_definitions( t8project PUBLIC T8PROJECT_VTK_VERSION_USED="${VTK_MAJOR_VERSION}.${VTK_MINOR_VERSION}" )
+
+    # Define T8PROJECT_VTK_VERSION_USED for internal and external use in source files.
+    # Note, external libraries linking against t8code (i.e. using find_package ( T8CODE REQUIRED )) can
+    # use T8PROJECT_VTK_VERSION_USED in source code and in CMake scripts (triggered by config.cmake.in).
+    target_compile_definitions( t8project PUBLIC T8PROJECT_VTK_VERSION_USED="${T8PROJECT_VTK_VERSION_USED}" )
     target_compile_definitions( t8project PUBLIC T8PROJECT_ENABLE_VTK=1 )
     target_include_directories( t8project PUBLIC ${VTK_INCLUDE_DIR} )
     target_link_libraries( t8project PUBLIC ${VTK_LIBRARIES} )
@@ -39,23 +44,8 @@ if( T8PROJECT_ENABLE_VTK )
 #    install( FILES
 #     put/header/file/here
 #    DESTINATION include)
-else ()
-    unset ( T8PROJECT_VTK_MAJOR_VERSION )
-    unset ( T8PROJECT_VTK_MINOR_VERSION )
 endif()
 
-#
-# Setup the file t8project_vtk_linkage.hxx and write macros for the VTK version
-#
-configure_file (t8project_vtk_linkage.hxx.in t8project_vtk_linkage.hxx @ONLY)
-
-
-# install the automatically created t8project_vtk_linkage.hxx into the include folder
-install (FILES 
-    ${CMAKE_CURRENT_BINARY_DIR}/t8project_vtk_linkage.hxx
-    DESTINATION include
-)
-
 # Make this package available as a cmake install package, so 
 # that other projects can find it with find_package.
 include( CMakePackageConfigHelpers )

src/config.cmake.in

@@ -6,6 +6,13 @@ find_dependency( T8CODE CONFIG )
 find_dependency( P4EST CONFIG )
 find_dependency( SC CONFIG )
 
+if(T8PROJECT_ENABLE_VTK)
+    find_dependency(VTK)
+    # Expose the variable T8PROJECT_VTK_VERSION_USED to external CMake scripts linking against t8code
+    # for example with find_package ( T8PROJECT REQUIRED )
+    set (T8PROJECT_VTK_VERSION_USED "@T8PROJECT_VTK_VERSION_USED@")
+endif()
+
 include( "${CMAKE_CURRENT_LIST_DIR}/@PROJECT_NAME@-targets.cmake" )
 
 check_required_components( @PROJECT_NAME@ )

test/t8project_gtest_vtk_linkage.cxx

@@ -29,55 +29,12 @@
  * does nothing and is always passed.
  */
 #include <iostream>
-#include <t8_vtk/t8_vtk_linkage.hxx>
 #include <gtest/gtest.h>
-#include <t8project_vtk_linkage.hxx>
 #if T8PROJECT_ENABLE_VTK
 #include <vtkUnstructuredGrid.h>
-#include <vtkVersionMacros.h>
 #include <vtkNew.h>
 #endif
 
-/* Test correct macro dependencies.
- * Will throw a compile time error if T8PROJECT_ENABLE_VTK is O
- * but T8PROJECT_VTK_VERSION_USED or T8PROJECT_VTK_MAJOR_VERSION or T8PROJECT_VTK_MINOR_VERSION is defined. */
-#if not T8PROJECT_ENABLE_VTK
-#ifdef T8PROJECT_VTK_VERSION_USED
-#error Configuration error: T8PROJECT_VTK_VERSION_USED is defined despite \
- T8PROJECT_ENABLE_VTK not being defined.
-#endif
-
-#ifdef T8PROJECT_VTK_MAJOR_VERSION
-#error Configuration error: T8PROJECT_VTK_MAJOR_VERSION is defined despite \
- T8PROJECT_ENABLE_VTK not being defined.
-#endif
-
-#ifdef T8PROJECT_VTK_MINOR_VERSION
-#error Configuration error: T8PROJECT_VTK_MINOR_VERSION is defined despite \
- T8PROJECT_ENABLE_VTK not being defined.
-#endif
-#endif
-
-
-/* Test correct macro dependencies.
- * Will throw a compile time error if T8PROJECT_ENABLE_VTK is 1
- * but one of T8PROJECT_VTK_VERSION_USED, T8PROJECT_VTK_MAJOR_VERSION, T8PROJECT_VTK_MINOR_VERSION is not defined.
- */
-#if T8PROJECT_ENABLE_VTK
-#ifndef T8PROJECT_VTK_VERSION_USED
-#error Configuration error: T8PROJECT_ENABLE_VTK is defined despite \
- T8PROJECT_VTK_VERSION_USED not being defined.
-#endif
-#ifndef T8PROJECT_VTK_MAJOR_VERSION
-#error Configuration error: T8PROJECT_ENABLE_VTK is defined despite \
- T8PROJECT_VTK_MAJOR_VERSION not being defined.
-#endif
-#ifndef T8PROJECT_VTK_MINOR_VERSION
-#error Configuration error: T8PROJECT_ENABLE_VTK is defined despite \
- T8PROJECT_VTK_MINOR_VERSION not being defined.
-#endif
-#endif
-
 /* Check whether T8PROJECT_VTK_VERSION_USED equals VTK_MAJOR_VERSION.VTK_MINOR_VERSION */
 TEST (t8project_gtest_vtk_linkage, t8project_test_vtk_version_number)
 {
@@ -90,20 +47,28 @@ TEST (t8project_gtest_vtk_linkage, t8project_test_vtk_version_number)
   if (!strcmp (T8PROJECT_VTK_VERSION_USED, vtk_version)) {
     std::cout << "Using vtk version " << vtk_version << std::endl;
   }
-  EXPECT_EQ (T8PROJECT_VTK_MAJOR_VERSION, VTK_MAJOR_VERSION);
-  EXPECT_EQ (T8PROJECT_VTK_MINOR_VERSION, VTK_MINOR_VERSION);
 #endif
 }
 
-/* Check whether T8PROJECT_VTK_VERSION_USED equals VTK_MAJOR_VERSION.VTK_MINOR_VERSION */
-TEST (t8project_gtest_vtk_linkage, t8code_compatibility)
+/* Check whether T8PROJECT_VTK_VERSION_USED equals T8_VTK_VERSION_USED */
+TEST (t8project_gtest_vtk_linkage, t8project_and_t8code_use_same_vtk_version)
 {
-#if T8_ENABLE_VTK
-  EXPECT_EQ (T8PROJECT_VTK_MAJOR_VERSION, T8_MAJOR_VERSION) << "VTK version mismatch. t8code uses a different VTK major version.\n";
-  EXPECT_EQ (T8PROJECT_VTK_MINOR_VERSION, T8_MINOR_VERSION) << "VTK version mismatch. t8code uses a different VTK major version.\n";
+#if T8PROJECT_ENABLE_VTK
+  EXPECT_FALSE (strcmp (T8PROJECT_VTK_VERSION_USED, T8_VTK_VERSION_USED))
+    << "linked vtk version (" << T8PROJECT_VTK_VERSION_USED << ") does not equal the version t8code was configured with ("
+    << T8_VTK_VERSION_USED << ").\n";
 #endif
 }
 
+TEST (t8project_gtest_vtk_linkage, t8project_uses_vtk_if_t8code_does)
+{
+  #if T8_ENABLE_VTK
+    #if !T8PROJECT_ENABLE_VTK
+      ASSERT_FALSE (true) << "t8code was linked against VTK but t8project was not.";
+    #endif
+  #endif  
+}
+
 /* Check whether we can successfully execute VTK code */
 TEST (t8project_gtest_vtk_linkage, t8project_test_vtk_linkage)
 {