Build : Allow building from separate dependencies

Rather than using the public gaffer dependencies, we might want to build against separate boost, python, tbb, exr, and cortex installations.

CMakeLists.txt

@@ -1,6 +1,8 @@
 cmake_minimum_required(VERSION 3.0)
 project(AtomsGaffer)
 
+option( USE_GAFFER_DEPENDENCIES "Turn this off you're building against your own dependencies (eg boost, python, tbb, exr, cortex) rather than the versions included with Gaffer" ON )
+
 set(CMAKE_CXX_STANDARD 11)
 set(CMAKE_VERBOSE_MAKEFILE OFF)
 
@@ -16,12 +18,30 @@ if(ATOMS_ROOT)
     set(ATOMS_ICONS_PATH ${ATOMS_ROOT}/icons)
 endif()
 
+if(USE_GAFFER_DEPENDENCIES)
+    set(BOOST_INCLUDE_PATH ${GAFFER_ROOT}/include)
+    set(PYTHON_ROOT ${GAFFER_ROOT})
+    set(TBB_ROOT ${GAFFER_ROOT})
+    set(OPENEXR_ROOT ${GAFFER_ROOT})
+    set(CORTEX_ROOT ${GAFFER_ROOT})
+endif()
+
+set(DEPENDENCY_INCLUDE_PATHS
+    ${BOOST_INCLUDE_PATH}
+    ${TBB_ROOT}/include
+    ${OPENEXR_ROOT}/include
+    ${OPENEXR_ROOT}/include/OpenEXR
+    ${CORTEX_ROOT}/include
+    ${GAFFER_ROOT}/include
+    ${ATOMS_INCLUDE_PATH}
+)
+
 # build the library
 file( GLOB AtomsGafferSrc src/AtomsGaffer/*.cpp )
 link_directories( AtomsGaffer ${GAFFER_ROOT}/lib ${ATOMS_LIB_PATH} )
 add_library( AtomsGaffer SHARED ${AtomsGafferSrc} )
 target_compile_definitions( AtomsGaffer PRIVATE BOOST_SIGNALS_NO_DEPRECATION_WARNING=1 LINUX=1 )
-target_include_directories( AtomsGaffer PRIVATE include ${GAFFER_ROOT}/include ${ATOMS_INCLUDE_PATH} ${GAFFER_ROOT}/include/OpenEXR )
+target_include_directories( AtomsGaffer PRIVATE include ${DEPENDENCY_INCLUDE_PATHS} )
 target_link_libraries( AtomsGaffer Gaffer GafferScene AtomsProcedural )
 install( TARGETS AtomsGaffer DESTINATION lib )
 
@@ -31,7 +51,7 @@ add_library( AtomsGafferModule SHARED ${AtomsGafferModuleSrc} )
 set_target_properties( AtomsGafferModule PROPERTIES PREFIX "" OUTPUT_NAME "_AtomsGaffer" )
 target_compile_definitions( AtomsGafferModule PRIVATE BOOST_SIGNALS_NO_DEPRECATION_WARNING=1 LINUX=1 )
 target_link_libraries( AtomsGafferModule AtomsGaffer )
-target_include_directories( AtomsGafferModule PRIVATE include ${GAFFER_ROOT}/include ${GAFFER_ROOT}/include/OpenEXR  ${GAFFER_ROOT}/include/python2.7 ${ATOMS_INCLUDE_PATH} )
+target_include_directories( AtomsGafferModule PRIVATE include ${DEPENDENCY_INCLUDE_PATHS} ${PYTHON_ROOT}/include/python2.7 )
 target_link_libraries( AtomsGafferModule GafferBindings )
 install( TARGETS AtomsGafferModule DESTINATION python/AtomsGaffer )