From d0004865e5a7a24498c83a01dc8c8eca27136de8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20Vondru=C5=A1?= <mosra@centrum.cz>
Date: Thu, 21 Jun 2018 12:30:23 +0200
Subject: [PATCH] modules: properly handle GLVND also in case of context
 libraries.

---
 modules/FindMagnum.cmake | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/modules/FindMagnum.cmake b/modules/FindMagnum.cmake
index 63c647d2e..f111b2422 100644
--- a/modules/FindMagnum.cmake
+++ b/modules/FindMagnum.cmake
@@ -722,11 +722,22 @@ foreach(_component ${Magnum_FIND_COMPONENTS})
 
             # GLX context dependencies
             if(_component STREQUAL GlxContext)
-                find_package(X11)
-                set_property(TARGET Magnum::${_component} APPEND PROPERTY
-                    INTERFACE_INCLUDE_DIRECTORIES ${X11_INCLUDE_DIR})
-                set_property(TARGET Magnum::${_component} APPEND PROPERTY
-                    INTERFACE_LINK_LIBRARIES ${X11_LIBRARIES})
+                # With GLVND (since CMake 3.11) we need to explicitly link to
+                # GLX because libOpenGL doesn't provide it. Also can't use
+                # OpenGL_OpenGL_FOUND, because that one is set also if GLVND is
+                # *not* found. If GLVND is not used, link to X11 instead.
+                set(OpenGL_GL_PREFERENCE GLVND)
+                find_package(OpenGL)
+                if(OPENGL_opengl_LIBRARY)
+                    set_property(TARGET Magnum::${_component} APPEND PROPERTY
+                        INTERFACE_LINK_LIBRARIES OpenGL::GLX)
+                else()
+                    find_package(X11)
+                    set_property(TARGET Magnum::${_component} APPEND PROPERTY
+                        INTERFACE_INCLUDE_DIRECTORIES ${X11_INCLUDE_DIR})
+                    set_property(TARGET Magnum::${_component} APPEND PROPERTY
+                        INTERFACE_LINK_LIBRARIES ${X11_LIBRARIES})
+                endif()
 
             # EGL context dependencies
             elseif(_component STREQUAL EglContext)