From 826e02b48d0cd9d7031dc3abc0c700c3efcb9302 Mon Sep 17 00:00:00 2001
From: xavi92 <xavi92@30fe4595-0a0c-4342-8851-515496e4dcbd>
Date: Sun, 27 Oct 2024 08:08:58 +0000
Subject: [PATCH] 3rdParty-devel: Install OpenGL headers only if needed

MinGW already distributes OpenGL headers and libraries under different
directories. In such cases, it is more sensible to rely on those than
the in-tree copies maintained by the project.

Note that, for some unknown reason, the include directories for the
OpenGL::GL target are not filled, even if find_package(OpenGL) is
successful and the library is found. Therefore, this commit works around
this limitation by finding GL/gl.h from a possible list of directories
inside the toolchain.


git-svn-id: https://svn.code.sf.net/p/speed-dreams/code/trunk@9606 30fe4595-0a0c-4342-8851-515496e4dcbd

Former-commit-id: f663966c6bd42cfcb2b5135b871bb2e2e1636994
Former-commit-id: 92e313ea0f1edc8e030021225dec2c347b69f86f
---
 packaging/3rdParty-devel/CMakeLists.txt | 43 ++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 4 deletions(-)

diff --git a/packaging/3rdParty-devel/CMakeLists.txt b/packaging/3rdParty-devel/CMakeLists.txt
index 2d675377..27942f87 100644
--- a/packaging/3rdParty-devel/CMakeLists.txt
+++ b/packaging/3rdParty-devel/CMakeLists.txt
@@ -156,14 +156,49 @@ else()
    set(SUPER_BUILD_POSTFIX "")
 endif()
 
-# OpenGL extensions (Windows only??)
-message(STATUS "OpenGL extensions (Windows only??)")
-if(WIN32 AND OPTION_OPENGL_HEADERS)
+# OpenGL extensions
+find_package(OpenGL)
+
+if(NOT TARGET OpenGL::GL)
+   message(STATUS "Copying in-tree OpenGL headers")
    ExternalProject_Add(OpenGL-headers
       URL ${CMAKE_CURRENT_SOURCE_DIR}/patches/openglheaders.zip
       URL_HASH SHA256=344debe6e65629d70020b6da056255de56c7d4fe48194336ea2cb896fc1b545b
       CMAKE_ARGS ${EXTERNALS_CMAKE_ARGS})
-endif(WIN32 AND OPTION_OPENGL_HEADERS)
+else()
+   if(TARGET OpenGL::GL)
+      add_library(OpenGL-headers ALIAS OpenGL::GL)
+
+      if(MINGW AND NOT OPENGL_INCLUDE_DIR)
+         get_filename_component(MINGW_BINDIR "${CMAKE_CXX_COMPILER}" PATH)
+         get_filename_component(MINGW_BINDIR "${MINGW_BINDIR}/../" REALPATH)
+
+         if(CMAKE_CROSSCOMPILING)
+            find_path(OPENGL_INCLUDE_DIR GL/gl.h
+               REQUIRED
+               NO_CMAKE_SYSTEM_PATH
+               NO_DEFAULT_PATH
+               NO_CMAKE_PATH
+               NO_CMAKE_INSTALL_PREFIX
+               HINTS
+                  "${MINGW_BINDIR}/include"
+                  "${MINGW_BINDIR}/*/include"
+            )
+         else()
+            find_path(OPENGL_INCLUDE_DIR GL/gl.h
+               REQUIRED
+               HINTS
+                  "${MINGW_BINDIR}/include"
+                  "${MINGW_BINDIR}/*/include"
+            )
+         endif()
+
+         # FindOpenGL.cmake seems not to set this property under
+         # some circumstances.
+         target_include_directories(OpenGL::GL INTERFACE ${OPENGL_INCLUDE_DIR})
+      endif()
+   endif()
+endif()
 
 if(OPTION_ZLIB)
    ExternalProject_Add(${ZLIB_PROJECT}