FILE(TO_CMAKE_PATH "$ENV{OPENGL_DIR}" TRY1_DIR)
FILE(TO_CMAKE_PATH "${OPENGL_DIR}" TRY2_DIR)
FILE(GLOB OPENGL_DIR ${TRY1_DIR} ${TRY2_DIR})

FIND_PATH(OPENGL_gl_INCLUDE_DIR GL/gl.h
                                PATHS ${OPENGL_DIR}/include /usr/local/include /usr/include
                                ENV INCLUDE DOC "Directory containing GL/gl.h include file")

FIND_PATH(OPENGL_glu_INCLUDE_DIR GL/glu.h
                                 PATHS ${OPENGL_DIR}/include /usr/local/include /usr/include
                                 ENV INCLUDE DOC "Directory containing GL/glu.h include file")

FIND_LIBRARY(OPENGL_gl_LIBRARY NAMES opengl32 GL
                               PATHS ${OPENGL_DIR}/bin ${OPENGL_DIR}/win32/bin ${OPENGL_DIR}/lib ${OPENGL_DIR}/win32/lib /usr/local/lib /usr/lib
                               ENV LIB
                               DOC "gl library to link with"
                               NO_SYSTEM_ENVIRONMENT_PATH)

FIND_LIBRARY(OPENGL_glu_LIBRARY NAMES glu32 GLU
                                PATHS ${OPENGL_DIR}/bin ${OPENGL_DIR}/win32/bin ${OPENGL_DIR}/lib ${OPENGL_DIR}/win32/lib /usr/local/lib /usr/lib
                                ENV LIB
                                DOC "glu library to link with"
                                NO_SYSTEM_ENVIRONMENT_PATH)

IF (OPENGL_gl_INCLUDE_DIR AND OPENGL_glu_INCLUDE_DIR AND OPENGL_gl_LIBRARY AND OPENGL_glu_LIBRARY)
  SET(OPENGL_INCLUDE_DIR ${OPENGL_gl_INCLUDE_DIR} ${OPENGL_glu_INCLUDE_DIR})
  list(REMOVE_DUPLICATES OPENGL_INCLUDE_DIR)
  SET(OPENGL_LIBRARIES ${OPENGL_gl_LIBRARY} ${OPENGL_glu_LIBRARY})
  list(REMOVE_DUPLICATES OPENGL_LIBRARIES)
ENDIF (OPENGL_gl_INCLUDE_DIR AND OPENGL_glu_INCLUDE_DIR AND OPENGL_gl_LIBRARY AND OPENGL_glu_LIBRARY)