Adapt to CMake 3.13's new meaning of OSGDB_LIBRARY (i.e. that it can now be a list) while allowing for the possibility that the found libraries may be in different directories when debug and optimised versions exist.

CMakeLists.txt

@@ -256,8 +256,14 @@ set(USED_OSG_PLUGINS
                     osgdb_tga
                   )
 
-get_filename_component(OSG_LIB_DIR ${OSGDB_LIBRARY} DIRECTORY)
-set(OSGPlugins_LIB_DIR "${OSG_LIB_DIR}/osgPlugins-${OPENSCENEGRAPH_VERSION}")
+set(OSGPlugins_LIB_DIR "")
+foreach(OSGDB_LIB ${OSGDB_LIBRARY})
+	# Skip library type names
+	if(EXISTS ${OSGDB_LIB})
+		get_filename_component(OSG_LIB_DIR ${OSGDB_LIB} DIRECTORY)
+		list(APPEND OSGPlugins_LIB_DIR "${OSG_LIB_DIR}/osgPlugins-${OPENSCENEGRAPH_VERSION}")
+	endif()
+endforeach(OSGDB_LIB)
 
 if(OSG_STATIC)
     add_definitions(-DOSG_LIBRARY_STATIC)
@@ -807,15 +813,24 @@ if (OPENMW_OSX_DEPLOYMENT AND APPLE AND DESIRED_QT_VERSION MATCHES 5)
 
     set(ABSOLUTE_PLUGINS "")
 
+    set(OSGPlugins_DONT_FIND_DEPENDENCIES 1)
+    find_package(OSGPlugins REQUIRED COMPONENTS ${USED_OSG_PLUGINS})
+
     foreach (PLUGIN_NAME ${USED_OSG_PLUGINS})
-      set(PLUGIN_ABS "${OSGPlugins_LIB_DIR}/${PLUGIN_NAME}.so")
-      set(ABSOLUTE_PLUGINS ${PLUGIN_ABS} ${ABSOLUTE_PLUGINS})
+        string(TOUPPER ${PLUGIN_NAME} PLUGIN_NAME_UC)
+        if(${PLUGIN_NAME_UC}_LIBRARY_RELEASE)
+            set(PLUGIN_ABS ${${PLUGIN_NAME_UC}_LIBRARY_RELEASE})
+        elseif(${PLUGIN_NAME_UC}_LIBRARY)
+            set(PLUGIN_ABS ${${PLUGIN_NAME_UC}_LIBRARY})
+        else()
+            message(FATAL_ERROR "Can't find library file for ${PLUGIN_NAME}")
+            # We used to construct the path manually from OSGPlugins_LIB_DIR and the plugin name.
+            # Maybe that could be restored as a fallback?
+        endif()
+        set(ABSOLUTE_PLUGINS ${PLUGIN_ABS} ${ABSOLUTE_PLUGINS})
     endforeach ()
 
-    get_filename_component(OSG_PLUGIN_PREFIX_DIR "${OSGPlugins_LIB_DIR}" NAME)
-    if (NOT OSG_PLUGIN_PREFIX_DIR)
-      message(FATAL_ERROR "Can't get directory name for OSG plugins from '${OSGPlugins_LIB_DIR}'")
-    endif()
+    set(OSG_PLUGIN_PREFIX_DIR "osgPlugins-${OPENSCENEGRAPH_VERSION}")
 
     # installs used plugins in bundle at given path (bundle_path must be relative to ${CMAKE_INSTALL_PREFIX})
     # and returns list of install paths for all installed plugins

cmake/FindOSGPlugins.cmake

@@ -1,5 +1,6 @@
 # This module accepts the following env variable
 #  OSGPlugins_LIB_DIR - <OpenSceneGraph>/lib/osgPlugins-<X.X.X> , path to search plugins
+#  OSGPlugins_DONT_FIND_DEPENDENCIES - Set to skip also finding png, zlib and jpeg
 #
 # Once done this will define
 #  OSGPlugins_FOUND         - System has the all required components.
@@ -27,10 +28,10 @@ foreach(_library ${OSGPlugins_FIND_COMPONENTS})
     set(_component OSGPlugins_${_library})
 
     set(${_library_uc}_DIR ${OSGPlugins_LIB_DIR}) # to help function osg_find_library
-    set(_saved_lib_prefix ${CMAKE_FIND_LIBRARY_PREFIXES}) # save CMAKE_FIND_LIBRARY_PREFIXES
-    set(CMAKE_FIND_LIBRARY_PREFIXES "") # search libraries with no prefix
+    #set(_saved_lib_prefix ${CMAKE_FIND_LIBRARY_PREFIXES}) # save CMAKE_FIND_LIBRARY_PREFIXES
+    #set(CMAKE_FIND_LIBRARY_PREFIXES "") # search libraries with no prefix
     osg_find_library(${_library_uc} ${_library}) # find it into ${_library_uc}_LIBRARIES
-    set(CMAKE_FIND_LIBRARY_PREFIXES ${_saved_lib_prefix}) # restore prefix
+    #set(CMAKE_FIND_LIBRARY_PREFIXES ${_saved_lib_prefix}) # restore prefix
 
     if (${_library_uc}_LIBRARIES)
         set(${_component}_LIBRARY ${${_library_uc}_LIBRARIES}) # fake as if we call find_library
@@ -41,10 +42,12 @@ foreach(_library ${OSGPlugins_FIND_COMPONENTS})
     list(APPEND OSGPlugins_PROCESS_LIBS ${_component}_LIBRARY)
 endforeach()
 
-foreach(_dependency PNG ZLIB JPEG) # needed by osgdb_png or osgdb_jpeg
-    libfind_package(OSGPlugins ${_dependency})
-    set(${_dependency}_LIBRARY_OPTS ${_dependency}_LIBRARY)
-    #list(APPEND OSGPlugins_PROCESS_LIBS ${_dependency}_LIBRARY)
-endforeach()
+if(NOT DEFINED OSGPlugins_DONT_FIND_DEPENDENCIES)
+    foreach(_dependency PNG ZLIB JPEG) # needed by osgdb_png or osgdb_jpeg
+        libfind_package(OSGPlugins ${_dependency})
+        set(${_dependency}_LIBRARY_OPTS ${_dependency}_LIBRARY)
+        #list(APPEND OSGPlugins_PROCESS_LIBS ${_dependency}_LIBRARY)
+    endforeach()
+endif()
 
 libfind_process(OSGPlugins)