Only add Open Babel if requested and found

Signed-off-by: Geoff Hutchison <[email protected]>

avogadro/qtplugins/forcefield/CMakeLists.txt

@@ -6,13 +6,15 @@ set(forcefield_srcs
 )
 
 if (BUILD_GPL_PLUGINS)
-  find_package(OpenBabel3 REQUIRED)
-  list(APPEND forcefield_srcs
-    obenergy.cpp
-  )
-  add_definitions(-DBUILD_GPL_PLUGINS)
-  include_directories(${OpenBabel3_INCLUDE_DIRS} ${OpenBabel3_INCLUDE_DIR}
-  ${AvogadroLibs_BINARY_DIR}/../prefix/include/openbabel3)
+  find_package(OpenBabel3)
+  if (OpenBabel3_LIBRARY)
+    list(APPEND forcefield_srcs
+      obenergy.cpp
+    )
+    add_definitions(-DBUILD_GPL_PLUGINS)
+    include_directories(${OpenBabel3_INCLUDE_DIRS} ${OpenBabel3_INCLUDE_DIR}
+    ${AvogadroLibs_BINARY_DIR}/../prefix/include/openbabel3)
+  endif()
 endif()
 
 avogadro_plugin(Forcefield
@@ -26,20 +28,26 @@ avogadro_plugin(Forcefield
 
 target_link_libraries(Forcefield PRIVATE Avogadro::Calc)
 
-if (BUILD_GPL_PLUGINS)
+if (BUILD_GPL_PLUGINS AND OpenBabel3_LIBRARY)
   target_link_libraries(Forcefield PRIVATE OpenBabel3)
 endif()
 
 # Bundled forcefield scripts
 set(forcefields
   scripts/ani2x.py
-  scripts/gaff.py
   scripts/gfn1.py
   scripts/gfn2.py
   scripts/gfnff.py
-  scripts/mmff94.py
-  scripts/uff.py
 )
 
+if (NOT BUILD_GPL_PLUGINS)
+  # install the OB / Pybel forcefield scripts
+  list(APPEND forcefields
+    scripts/gaff.py
+    scripts/mmff94.py
+    scripts/uff.py
+  )
+endif()
+
 install(PROGRAMS ${forcefields}
 DESTINATION "${INSTALL_LIBRARY_DIR}/avogadro2/scripts/energy/")