macOS: Support non-system level Vulkan SDK installs, with fallback to…

… MoltenVK library

CMakeLists.txt

@@ -91,6 +91,32 @@ ELSEIF(LINUX)
 		set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DVK_USE_PLATFORM_XCB_KHR")
 	ENDIF(USE_D2D_WSI)
 ELSEIF(APPLE)
+	IF (CMAKE_GENERATOR MATCHES "Xcode")
+		# Suppress regeneration for Xcode since environment variables will be lost if not set in Xcode locations/custom paths
+		set(CMAKE_SUPPRESS_REGENERATION ON)
+		set(CMAKE_XCODE_GENERATE_SCHEME ON)
+		IF (Vulkan_FOUND)
+			# If the Vulkan loader was found and its environment variables are defined, make them available within Xcode schemes
+			IF (DEFINED ENV{VK_ADD_LAYER_PATH})
+				set(CMAKE_XCODE_SCHEME_ENVIRONMENT "VK_ADD_LAYER_PATH=$ENV{VK_ADD_LAYER_PATH}")
+			ENDIF()
+			IF (DEFINED ENV{VK_ICD_FILENAMES})
+				set(CMAKE_XCODE_SCHEME_ENVIRONMENT "${CMAKE_XCODE_SCHEME_ENVIRONMENT};VK_ICD_FILENAMES=$ENV{VK_ICD_FILENAMES}")
+			ENDIF()
+			IF (DEFINED ENV{VK_DRIVER_FILES})
+				set(CMAKE_XCODE_SCHEME_ENVIRONMENT "${CMAKE_XCODE_SCHEME_ENVIRONMENT};VK_DRIVER_FILES=$ENV{VK_DRIVER_FILES}")
+			ENDIF()
+		ENDIF()
+	ENDIF()
+	IF (NOT Vulkan_FOUND)
+		# If the Vulkan loader was not found, then look for libMoltenVK.dylib in the Vulkan SDK and legacy MoltenVK locations
+		set(CMAKE_FIND_FRAMEWORK NEVER)
+		find_library(Vulkan_LIBRARY NAMES MoltenVK HINTS "$ENV{VULKAN_SDK}/lib" "$ENV{VULKAN_SDK}/dylib/macos" REQUIRED)
+		IF (Vulkan_LIBRARY)
+			set(Vulkan_FOUND ON)
+			MESSAGE(STATUS "Using MoltenVK Vulkan Portability library")
+		ENDIF()
+	ENDIF()
 	set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DVK_USE_PLATFORM_METAL_EXT -DVK_EXAMPLE_XCODE_GENERATED")
 	# Todo : android?
 ENDIF(WIN32)