Added FindSDL2 cmake file for modernization of our gl example

cmake/FindSDL2.cmake

@@ -0,0 +1,193 @@
+# Locate SDL2 library
+# This module defines
+# SDL2_LIBRARY, the name of the library to link against
+# SDL2_FOUND, if false, do not try to link to SDL2
+# SDL2_INCLUDE_DIR, where to find SDL.h
+#
+# This module responds to the the flag:
+# SDL2_BUILDING_LIBRARY
+# If this is defined, then no SDL2_main will be linked in because
+# only applications need main().
+# Otherwise, it is assumed you are building an application and this
+# module will attempt to locate and set the the proper link flags
+# as part of the returned SDL2_LIBRARY variable.
+#
+# Don't forget to include SDL2main.h and SDL2main.m your project for the
+# OS X framework based version. (Other versions link to -lSDL2main which
+# this module will try to find on your behalf.) Also for OS X, this
+# module will automatically add the -framework Cocoa on your behalf.
+#
+#
+# Additional Note: If you see an empty SDL2_LIBRARY_TEMP in your configuration
+# and no SDL2_LIBRARY, it means CMake did not find your SDL2 library
+# (SDL2.dll, libsdl2.so, SDL2.framework, etc).
+# Set SDL2_LIBRARY_TEMP to point to your SDL2 library, and configure again.
+# Similarly, if you see an empty SDL2MAIN_LIBRARY, you should set this value
+# as appropriate. These values are used to generate the final SDL2_LIBRARY
+# variable, but when these values are unset, SDL2_LIBRARY does not get created.
+#
+#
+# $SDL2DIR is an environment variable that would
+# correspond to the ./configure --prefix=$SDL2DIR
+# used in building SDL2.
+# l.e.galup  9-20-02
+#
+# Modified by Eric Wing.
+# Added code to assist with automated building by using environmental variables
+# and providing a more controlled/consistent search behavior.
+# Added new modifications to recognize OS X frameworks and
+# additional Unix paths (FreeBSD, etc).
+# Also corrected the header search path to follow "proper" SDL2 guidelines.
+# Added a search for SDL2main which is needed by some platforms.
+# Added a search for threads which is needed by some platforms.
+# Added needed compile switches for MinGW.
+#
+# On OSX, this will prefer the Framework version (if found) over others.
+# People will have to manually change the cache values of
+# SDL2_LIBRARY to override this selection or set the CMake environment
+# CMAKE_INCLUDE_PATH to modify the search paths.
+#
+# Note that the header path has changed from SDL2/SDL.h to just SDL.h
+# This needed to change because "proper" SDL2 convention
+# is #include "SDL.h", not <SDL2/SDL.h>. This is done for portability
+# reasons because not all systems place things in SDL2/ (see FreeBSD).
+#
+# Ported by Johnny Patterson. This is a literal port for SDL2 of the FindSDL.cmake
+# module with the minor edit of changing "SDL" to "SDL2" where necessary. This
+# was not created for redistribution, and exists temporarily pending official
+# SDL2 CMake modules.
+
+#=============================================================================
+# Copyright 2003-2009 Kitware, Inc.
+#
+# Distributed under the OSI-approved BSD License (the "License");
+# see accompanying file Copyright.txt for details.
+#
+# This software is distributed WITHOUT ANY WARRANTY; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the License for more information.
+#=============================================================================
+# (To distribute this file outside of CMake, substitute the full
+#  License text for the above reference.)
+
+
+FIND_PATH(SDL2_INCLUDE_DIR SDL.h
+  HINTS
+  $ENV{SDL2DIR}
+  PATH_SUFFIXES include/SDL2 include
+  PATHS
+  ~/Library/Frameworks
+  /Library/Frameworks
+  /usr/local/include/SDL2
+  /usr/include/SDL2
+  /sw # Fink
+  /opt/local # DarwinPorts
+  /opt/csw # Blastwave
+  /opt
+)
+#MESSAGE("SDL2_INCLUDE_DIR is ${SDL2_INCLUDE_DIR}")
+
+FIND_LIBRARY(SDL2_LIBRARY_TEMP
+  NAMES SDL2
+  HINTS
+  $ENV{SDL2DIR}
+  PATH_SUFFIXES lib64 lib
+  PATHS
+  /sw
+  /opt/local
+  /opt/csw
+  /opt
+)
+
+#MESSAGE("SDL2_LIBRARY_TEMP is ${SDL2_LIBRARY_TEMP}")
+
+IF(NOT SDL2_BUILDING_LIBRARY)
+  IF(NOT ${SDL2_INCLUDE_DIR} MATCHES ".framework")
+    # Non-OS X framework versions expect you to also dynamically link to
+    # SDL2main. This is mainly for Windows and OS X. Other (Unix) platforms
+    # seem to provide SDL2main for compatibility even though they don't
+    # necessarily need it.
+    FIND_LIBRARY(SDL2MAIN_LIBRARY
+      NAMES SDL2main
+      HINTS
+      $ENV{SDL2DIR}
+      PATH_SUFFIXES lib64 lib
+      PATHS
+      /sw
+      /opt/local
+      /opt/csw
+      /opt
+    )
+  ENDIF(NOT ${SDL2_INCLUDE_DIR} MATCHES ".framework")
+ENDIF(NOT SDL2_BUILDING_LIBRARY)
+
+# SDL2 may require threads on your system.
+# The Apple build may not need an explicit flag because one of the
+# frameworks may already provide it.
+# But for non-OSX systems, I will use the CMake Threads package.
+IF(NOT APPLE)
+  FIND_PACKAGE(Threads)
+ENDIF(NOT APPLE)
+
+# MinGW needs an additional library, mwindows
+# It's total link flags should look like -lmingw32 -lSDL2main -lSDL2 -lmwindows
+# (Actually on second look, I think it only needs one of the m* libraries.)
+IF(MINGW)
+  SET(MINGW32_LIBRARY mingw32 CACHE STRING "mwindows for MinGW")
+ENDIF(MINGW)
+
+SET(SDL2_FOUND "NO")
+IF(SDL2_LIBRARY_TEMP)
+  # For SDL2main
+  IF(NOT SDL2_BUILDING_LIBRARY)
+    IF(SDL2MAIN_LIBRARY)
+      SET(SDL2_LIBRARY_TEMP ${SDL2MAIN_LIBRARY} ${SDL2_LIBRARY_TEMP})
+    ENDIF(SDL2MAIN_LIBRARY)
+  ENDIF(NOT SDL2_BUILDING_LIBRARY)
+
+  # For OS X, SDL2 uses Cocoa as a backend so it must link to Cocoa.
+  # CMake doesn't display the -framework Cocoa string in the UI even
+  # though it actually is there if I modify a pre-used variable.
+  # I think it has something to do with the CACHE STRING.
+  # So I use a temporary variable until the end so I can set the
+  # "real" variable in one-shot.
+  IF(APPLE)
+    SET(SDL2_LIBRARY_TEMP ${SDL2_LIBRARY_TEMP} "-framework Cocoa")
+  ENDIF(APPLE)
+
+  # For threads, as mentioned Apple doesn't need this.
+  # In fact, there seems to be a problem if I used the Threads package
+  # and try using this line, so I'm just skipping it entirely for OS X.
+  IF(NOT APPLE)
+    SET(SDL2_LIBRARY_TEMP ${SDL2_LIBRARY_TEMP} ${CMAKE_THREAD_LIBS_INIT})
+  ENDIF(NOT APPLE)
+
+  # For MinGW library
+  IF(MINGW)
+    SET(SDL2_LIBRARY_TEMP ${MINGW32_LIBRARY} ${SDL2_LIBRARY_TEMP})
+  ENDIF(MINGW)
+  
+  IF(WIN32)
+    SET(SDL2_LIBRARY_TEMP winmm imm32 version msimg32 ${SDL2_LIBRARY_TEMP})
+  ENDIF(WIN32)
+
+  # Set the final string here so the GUI reflects the final state.
+  SET(SDL2_LIBRARY ${SDL2_LIBRARY_TEMP} CACHE STRING "Where the SDL2 Library can be found")
+  # Set the temp variable to INTERNAL so it is not seen in the CMake GUI
+  SET(SDL2_LIBRARY_TEMP "${SDL2_LIBRARY_TEMP}" CACHE INTERNAL "")
+
+  SET(SDL2_FOUND "YES")
+ENDIF(SDL2_LIBRARY_TEMP)
+
+INCLUDE(FindPackageHandleStandardArgs)
+
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(SDL2
+                                  REQUIRED_VARS SDL2_LIBRARY SDL2_INCLUDE_DIR)
+
+IF(SDL2_STATIC)
+  if (UNIX AND NOT APPLE)
+    EXECUTE_PROCESS(COMMAND sdl2-config --static-libs OUTPUT_VARIABLE SDL2_LINK_FLAGS)
+    STRING(REGEX REPLACE "(\r?\n)+$" "" SDL2_LINK_FLAGS "${SDL2_LINK_FLAGS}")
+    SET(SDL2_LIBRARY ${SDL2_LINK_FLAGS})
+  ENDIF()
+ENDIF(SDL2_STATIC)