Better usage of external OpenGL headers.

Moved them to `OpenGL/` subdirectory, allowing them to be included
explicitly with e.g. <OpenGL/GLES2/gl2ext.h> overriding the system
<GLES2/gl2ext.h> header. Our versions of the headers are thus now
explicitly included in `OpenGL.h`, but they can be also included using
no-prefix path if no system version is available. It might break some ES
platforms, they will be fixed when found.

The headers are now installed into `Magnum/OpenGL` (not into any
artificial `external` directory). Now also installing GLES2 headers for
OpenGL ES 2 (previously ES3 headers were installed for both ES2 and
ES3).

CMakeLists.txt

@@ -104,8 +104,6 @@ set(MAGNUM_LIBRARY_INSTALL_DIR ${CMAKE_INSTALL_PREFIX}/lib${LIB_SUFFIX})
 set(MAGNUM_CMAKE_MODULE_INSTALL_DIR ${CMAKE_ROOT}/Modules)
 set(MAGNUM_INCLUDE_INSTALL_DIR ${CMAKE_INSTALL_PREFIX}/include/Magnum)
 
-include_directories(${CMAKE_SOURCE_DIR}/external)
-
 add_subdirectory(external)
 add_subdirectory(modules)
 add_subdirectory(src)

external/CMakeLists.txt

@@ -22,9 +22,4 @@
 #   DEALINGS IN THE SOFTWARE.
 #
 
-if(NOT TARGET_GLES)
-    add_subdirectory(GL)
-else()
-    add_subdirectory(GLES3)
-    add_subdirectory(KHR)
-endif()
+add_subdirectory(OpenGL)

external/OpenGL/CMakeLists.txt

@@ -0,0 +1,34 @@
+#
+#   This file is part of Magnum.
+#
+#   Copyright © 2010, 2011, 2012, 2013 Vladimír Vondruš <mosra@centrum.cz>
+#
+#   Permission is hereby granted, free of charge, to any person obtaining a
+#   copy of this software and associated documentation files (the "Software"),
+#   to deal in the Software without restriction, including without limitation
+#   the rights to use, copy, modify, merge, publish, distribute, sublicense,
+#   and/or sell copies of the Software, and to permit persons to whom the
+#   Software is furnished to do so, subject to the following conditions:
+#
+#   The above copyright notice and this permission notice shall be included
+#   in all copies or substantial portions of the Software.
+#
+#   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+#   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+#   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+#   THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+#   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+#   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+#   DEALINGS IN THE SOFTWARE.
+#
+
+if(NOT TARGET_GLES)
+    add_subdirectory(GL)
+else()
+    add_subdirectory(KHR)
+    if(TARGET_GLES2)
+        add_subdirectory(GLES2)
+    else()
+        add_subdirectory(GLES3)
+    endif()
+endif()

external/OpenGL/GL/CMakeLists.txt

@@ -22,4 +22,4 @@
 #   DEALINGS IN THE SOFTWARE.
 #
 
-install(FILES glcorearb.h DESTINATION ${MAGNUM_INCLUDE_INSTALL_DIR}/external/GL)
+install(FILES glcorearb.h DESTINATION ${MAGNUM_INCLUDE_INSTALL_DIR}/OpenGL/GL)

external/OpenGL/GLES2/CMakeLists.txt

@@ -0,0 +1,25 @@
+#
+#   This file is part of Magnum.
+#
+#   Copyright © 2010, 2011, 2012, 2013 Vladimír Vondruš <mosra@centrum.cz>
+#
+#   Permission is hereby granted, free of charge, to any person obtaining a
+#   copy of this software and associated documentation files (the "Software"),
+#   to deal in the Software without restriction, including without limitation
+#   the rights to use, copy, modify, merge, publish, distribute, sublicense,
+#   and/or sell copies of the Software, and to permit persons to whom the
+#   Software is furnished to do so, subject to the following conditions:
+#
+#   The above copyright notice and this permission notice shall be included
+#   in all copies or substantial portions of the Software.
+#
+#   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+#   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+#   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+#   THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+#   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+#   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+#   DEALINGS IN THE SOFTWARE.
+#
+
+install(FILES gl2.h gl2platform.h gl2ext.h DESTINATION ${MAGNUM_INCLUDE_INSTALL_DIR}/OpenGL/GLES2)

external/OpenGL/GLES3/CMakeLists.txt

@@ -22,4 +22,4 @@
 #   DEALINGS IN THE SOFTWARE.
 #
 
-install(FILES gl3.h gl3platform.h DESTINATION ${MAGNUM_INCLUDE_INSTALL_DIR}/external/GLES3)
+install(FILES gl3.h gl3platform.h DESTINATION ${MAGNUM_INCLUDE_INSTALL_DIR}/OpenGL/GLES3)

external/OpenGL/KHR/CMakeLists.txt

@@ -22,4 +22,4 @@
 #   DEALINGS IN THE SOFTWARE.
 #
 
-install(FILES khrplatform.h DESTINATION ${MAGNUM_INCLUDE_INSTALL_DIR}/external/KHR)
+install(FILES khrplatform.h DESTINATION ${MAGNUM_INCLUDE_INSTALL_DIR}/OpenGL/KHR)

modules/FindMagnum.cmake

@@ -295,7 +295,7 @@ find_package_handle_standard_args(Magnum
 
 # Dependent libraries and includes
 set(MAGNUM_INCLUDE_DIRS ${MAGNUM_INCLUDE_DIR}
-    ${MAGNUM_INCLUDE_DIR}/external
+    ${MAGNUM_INCLUDE_DIR}/OpenGL
     ${CORRADE_INCLUDE_DIR})
 set(MAGNUM_LIBRARIES ${MAGNUM_LIBRARY}
     ${CORRADE_UTILITY_LIBRARY}

src/CMakeLists.txt

@@ -30,7 +30,16 @@ if(CORRADE_GCC46_COMPATIBILITY)
 endif()
 
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${CORRADE_CXX_FLAGS}")
-include_directories(${CMAKE_CURRENT_SOURCE_DIR} ${CMAKE_CURRENT_BINARY_DIR} ${CORRADE_INCLUDE_DIR})
+include_directories(
+    ${CMAKE_CURRENT_SOURCE_DIR}
+    ${CMAKE_CURRENT_BINARY_DIR}
+    ${CORRADE_INCLUDE_DIR}
+
+    # We can use both implicit include path (GLES2/gl2.h) where our headers can
+    # be overriden with system ones or explicit (OpenGL/GLES2/gl2ext.h) where
+    # only our headers will be used
+    ${CMAKE_SOURCE_DIR}/external
+    ${CMAKE_SOURCE_DIR}/external/OpenGL)
 
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/magnumConfigure.h.cmake
                ${CMAKE_CURRENT_BINARY_DIR}/magnumConfigure.h)

src/OpenGL.h

@@ -32,13 +32,16 @@
 
 #ifndef MAGNUM_TARGET_GLES
 #include <GL/glew.h>
-#include <GL/glcorearb.h>
+#include <OpenGL/GL/glcorearb.h>
 #else
+#include <OpenGL/KHR/khrplatform.h>
 #ifndef MAGNUM_TARGET_GLES2
-#include <GLES3/gl3.h>
+#include <OpenGL/GLES3/gl3platform.h>
+#include <OpenGL/GLES3/gl3.h>
 #else
-#include <GLES2/gl2.h>
-#include <GLES2/gl2ext.h>
+#include <OpenGL/GLES2/gl2platform.h>
+#include <OpenGL/GLES2/gl2.h>
+#include <OpenGL/GLES2/gl2ext.h>
 #endif
 #endif