Use the DXSDK_DIR variable when set

CMakeLists.txt

@@ -75,6 +75,18 @@ IF(NOT CMAKE_DEBUG_POSTFIX)
         FORCE)
 ENDIF()
 
+IF(NOT DXSDK_DIR)
+    STRING(REGEX REPLACE "\\\\" "/" DXSDK_DIR "$ENV{DXSDK_DIR}")
+ELSE()
+    STRING(REGEX REPLACE "\\\\" "/" DXSDK_DIR "${DXSDK_DIR}")
+ENDIF()
+IF(DXSDK_DIR)
+    MESSAGE(STATUS "Using DirectX SDK directory: ${DXSDK_DIR}")
+    SET(CMAKE_REQUIRED_INCLUDES ${CMAKE_REQUIRED_INCLUDES} "${DXSDK_DIR}/Include")
+    INCLUDE_DIRECTORIES("${DXSDK_DIR}/Include")
+    LINK_DIRECTORIES("${DXSDK_DIR}/Lib")
+ENDIF()
+
 IF(MSVC)
     # ???
     SET(CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO} -D_DEBUG")