#-------------------------------------------------------------------
# This file is stolen from part of the CMake build system for OGRE (Object-oriented Graphics Rendering Engine) http://www.ogre3d.org/
#
# The contents of this file are placed in the public domain. Feel
# free to make use of it in any way you like.
#-------------------------------------------------------------------

# - Try to find OpenGLES and EGL
# Once done this will define
#
#  OPENGLES2_FOUND        - system has OpenGLES
#  OPENGLES2_INCLUDE_DIR  - the GL include directory
#  OPENGLES2_LIBRARIES    - Link these to use OpenGLES
#
#  EGL_FOUND        - system has EGL
#  EGL_INCLUDE_DIR  - the EGL include directory
#  EGL_LIBRARIES    - Link these to use EGL

# Win32, Apple, and Android are not tested!
# Linux tested and works

# Slightly customised framework finder
macro(findpkg_framework fwk)
  if(APPLE)
    set(${fwk}_FRAMEWORK_PATH
      ${${fwk}_FRAMEWORK_SEARCH_PATH}
      ${CMAKE_FRAMEWORK_PATH}
      ~/Library/Frameworks
      /Library/Frameworks
      /System/Library/Frameworks
      /Network/Library/Frameworks
      ${CMAKE_CURRENT_SOURCE_DIR}/lib/macosx/Release
      ${CMAKE_CURRENT_SOURCE_DIR}/lib/macosx/Debug
    )
    # These could be arrays of paths, add each individually to the search paths
    foreach(i ${OGRE_PREFIX_PATH})
      set(${fwk}_FRAMEWORK_PATH ${${fwk}_FRAMEWORK_PATH} ${i}/lib/macosx/Release ${i}/lib/macosx/Debug)
    endforeach(i)

    foreach(i ${OGRE_PREFIX_BUILD})
      set(${fwk}_FRAMEWORK_PATH ${${fwk}_FRAMEWORK_PATH} ${i}/lib/macosx/Release ${i}/lib/macosx/Debug)
    endforeach(i)

    foreach(dir ${${fwk}_FRAMEWORK_PATH})
      set(fwkpath ${dir}/${fwk}.framework)
      if(EXISTS ${fwkpath})
        set(${fwk}_FRAMEWORK_INCLUDES ${${fwk}_FRAMEWORK_INCLUDES}
          ${fwkpath}/Headers ${fwkpath}/PrivateHeaders)
        set(${fwk}_FRAMEWORK_PATH ${dir})
        if (NOT ${fwk}_LIBRARY_FWK)
          set(${fwk}_LIBRARY_FWK "-framework ${fwk}")
        endif ()
      endif(EXISTS ${fwkpath})
    endforeach(dir)
  endif(APPLE)
endmacro(findpkg_framework)

macro(create_search_paths PREFIX)
  foreach(dir ${${PREFIX}_PREFIX_PATH})
    set(${PREFIX}_INC_SEARCH_PATH ${${PREFIX}_INC_SEARCH_PATH}
      ${dir}/include ${dir}/Include ${dir}/include/${PREFIX} ${dir}/Headers)
    set(${PREFIX}_LIB_SEARCH_PATH ${${PREFIX}_LIB_SEARCH_PATH}
      ${dir}/lib ${dir}/Lib ${dir}/lib/${PREFIX} ${dir}/Libs)
    set(${PREFIX}_BIN_SEARCH_PATH ${${PREFIX}_BIN_SEARCH_PATH}
      ${dir}/bin)
  endforeach(dir)
  if(ANDROID)
	set(${PREFIX}_LIB_SEARCH_PATH ${${PREFIX}_LIB_SEARCH_PATH} ${OGRE_DEPENDENCIES_DIR}/lib/${ANDROID_ABI})
  endif()
  set(${PREFIX}_FRAMEWORK_SEARCH_PATH ${${PREFIX}_PREFIX_PATH})
endmacro(create_search_paths)

if(WIN32)
	if(CYGWIN)
		find_path(OPENGLES2_INCLUDE_DIR GLES2/gl2.h)
		find_library(OPENGLES2_LIBRARY libGLESv2)
	else()
		if(BORLAND)
			set(OPENGLES2_LIBRARY import32 CACHE STRING "OpenGL ES 2.x library for Win32")
		else()
			# TODO
			# set(OPENGLES_LIBRARY ${SOURCE_DIR}/Dependencies/lib/release/libGLESv2.lib CACHE STRING "OpenGL ES 2.x library for win32"
		endif()
	endif()
elseif(APPLE)
	create_search_paths(/Developer/Platforms)
	findpkg_framework(OpenGLES2)
	set(OPENGLES2_LIBRARY "-framework OpenGLES")
else()
	find_path(OPENGLES2_INCLUDE_DIR GLES2/gl2.h
		PATHS /usr/openwin/share/include
			/opt/graphics/OpenGL/include
			/opt/vc/include
			/usr/X11R6/include
			/usr/include
	)

	find_library(OPENGLES2_LIBRARY
		NAMES GLESv2
		PATHS /opt/graphics/OpenGL/lib
			/usr/openwin/lib
			/usr/shlib /usr/X11R6/lib
			/opt/vc/lib
			/usr/lib/aarch64-linux-gnu
			/usr/lib/arm-linux-gnueabihf
			/usr/lib
	)

	if(NOT BUILD_ANDROID)
		find_path(EGL_INCLUDE_DIR EGL/egl.h
			PATHS /usr/openwin/share/include
				/opt/graphics/OpenGL/include
				/opt/vc/include
				/usr/X11R6/include
				/usr/include
		)

		find_library(EGL_LIBRARY
			NAMES EGL
			PATHS /opt/graphics/OpenGL/lib
				/usr/openwin/lib
				/usr/shlib
				/usr/X11R6/lib
				/opt/vc/lib
				/usr/lib/aarch64-linux-gnu
				/usr/lib/arm-linux-gnueabihf
				/usr/lib
		)

		# On Unix OpenGL usually requires X11.
		# It doesn't require X11 on OSX.

		if(OPENGLES2_LIBRARY)
			if(NOT X11_FOUND)
				include(FindX11)
			endif()
			if(X11_FOUND)
				set(OPENGLES2_LIBRARIES ${X11_LIBRARIES})
			endif()
		endif()
	endif()
endif()

set(OPENGLES2_LIBRARIES ${OPENGLES2_LIBRARIES} ${OPENGLES2_LIBRARY})

if(BUILD_ANDROID)
	if(OPENGLES2_LIBRARY)
		set(EGL_LIBRARIES)
		set(OPENGLES2_FOUND TRUE)
	endif()
else()
	if(OPENGLES2_LIBRARY AND EGL_LIBRARY)
		set(EGL_LIBRARIES ${EGL_LIBRARY} ${EGL_LIBRARIES})
		set(OPENGLES2_FOUND TRUE)
	endif()
endif()

mark_as_advanced(
	OPENGLES2_INCLUDE_DIR
	OPENGLES2_LIBRARY
	EGL_INCLUDE_DIR
	EGL_LIBRARY
)

if(OPENGLES2_FOUND)
	message(STATUS "Found system OpenGL ES 2 library: ${OPENGLES2_LIBRARIES}")
else()
	set(OPENGLES2_LIBRARIES "")
endif()