if (NOT FIND_INVRS_LOADED)

message (STATUS "Check for inVRs directory: ${INVRS_DIR}")

set (DEFAULT_INVRS_DIR ${CMAKE_CURRENT_SOURCE_DIR}/../../)

find_path (INVRS_DIR src/inVRs/SystemCore/SystemCore.h
        PATHS ${INVRS_DIR} ${DEFAULT_INVRS_DIR})

find_file (CHECK_INVRS_DIR src/inVRs/SystemCore/SystemCore.h
        PATHS ${INVRS_DIR})

if (NOT INVRS_DIR)
	message (FATAL_ERROR "Unable to find inVRs directory!\n"
		"Please pass the path to the inVRs directory to the cmake command, e.g.:\n"
		"\tcmake <path_to_inVRs> -DINVRS_DIR=/path/to/inVRs\n"
		"or enter the directory into the 'user.cmake' file\n"
		"You can download inVRs from http://www.inVRs.org\n")
elseif (NOT CHECK_INVRS_DIR)
	message (FATAL_ERROR "Invalid inVRs directory passed!\n"
		"The inVRs directory must contain the subfolder src/SystemCore, e.g.:\n"
		"\t/<INVRS_DIR>/src/SystemCore/SystemCore.h\n"
		"Please set the correct path in the 'user.cmake' file or pass it to cmake, e.g.:\n"
		"\tcmake <path_to_inVRs> -DINVRS_DIR=/path/to/inVRs")
else (NOT INVRS_DIR)
        message (STATUS "Check for inVRs directory: ${INVRS_DIR} - done")
endif (NOT INVRS_DIR)

message (STATUS "Check for inVRs include directory: ${INVRS_INCLUDE_DIR}")

find_path (INVRS_INCLUDE_DIR inVRs/SystemCore/SystemCore.h
	PATHS ${INVRS_INCLUDE_DIR} ${INVRS_DIR}/include)

find_file (CHECK_INVRS_INCLUDE_DIR inVRs/SystemCore/SystemCore.h
        PATHS ${INVRS_INCLUDE_DIR})

if (NOT INVRS_INCLUDE_DIR)
	message (FATAL_ERROR "Unable to find inVRs include directory!\n"
		"The include-files for the inVRs installation could not be found.\n"
		"The files are expected to be in:\n"
		"${INVRS_DIR}/include\n"
		"Please ensure that you built AND INSTALLED inVRs!\n")
elseif (NOT CHECK_INVRS_INCLUDE_DIR)
	message (FATAL_ERROR "Invalid inVRs include directory passed!\n"
		"The inVRs include directory must contain the subfolder inVRs/SystemCore, e.g.:\n"
		"\t/<INVRS_INCLUDE_DIR>/inVRs/SystemCore/SystemCore.h")
else (NOT INVRS_INCLUDE_DIR)
        message (STATUS "Check for inVRs include directory: ${INVRS_INCLUDE_DIR} - done")
endif (NOT INVRS_INCLUDE_DIR)

message (STATUS "Check for inVRs library directory: ${INVRS_LIB_DIR}")

if (WIN32)
find_path (INVRS_LIB_DIR inVRsSystemCore.lib
        PATHS ${INVRS_DIR}/lib)
find_file (CHECK_INVRS_LIB_DIR inVRsSystemCore.lib
        PATHS ${INVRS_LIB_DIR})
elseif (APPLE AND ${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
find_path (INVRS_LIB_DIR libinVRsSystemCore.dylib
        PATHS ${INVRS_LIB_DIR} ${INVRS_DIR}/lib)
find_file (CHECK_INVRS_LIB_DIR libinVRsSystemCore.dylib
        PATHS ${INVRS_LIB_DIR})
elseif (UNIX)
find_path (INVRS_LIB_DIR libinVRsSystemCore.so
	PATHS ${INVRS_LIB_DIR} ${INVRS_DIR}/lib)
find_file (CHECK_INVRS_LIB_DIR libinVRsSystemCore.so
        PATHS ${INVRS_LIB_DIR})
else (WIN32)
message (FATAL_ERROR "Unable to identify target operating system!")
endif (WIN32)

if (NOT INVRS_LIB_DIR)
	message (FATAL_ERROR "Unable to find inVRs libraries!\n"
		"The library-files for the inVRs installation could not be found.\n"
		"The files are expected to be in:\n"
		"${INVRS_DIR}/lib\n"
		"Please ensure that you built and installed inVRs!\n")
elseif (NOT CHECK_INVRS_LIB_DIR)
if (NOT WIN32)
	message (FATAL_ERROR "Invalid inVRs library directory passed!\n"
		"The inVRs library directory must contain the inVRs libraries, e.g.:\n"
		"\t/<INVRS_LIB_DIR>/libinVRsSystemCore.so")
else (NOT WIN32)
	message (FATAL_ERROR "Invalid inVRs library directory passed!\n"
		"The inVRs library directory must contain the inVRs libraries, e.g.:\n"
		"\t/<INVRS_LIB_DIR>/inVRsSystemCore.dll")
endif (NOT WIN32)
else (NOT INVRS_LIB_DIR)
        message (STATUS "Check for inVRs library directory: ${INVRS_LIB_DIR} - done")
endif (NOT INVRS_LIB_DIR)

set (INVRS_SOURCE_DIR ${INVRS_DIR})

set (FIND_INVRS_LOADED ON)
endif (NOT FIND_INVRS_LOADED)