From 7f74707ad6537da8b4b21c642c935a83eee6ca30 Mon Sep 17 00:00:00 2001
From: Adrien Guinet <adrien@guinet.me>
Date: Sun, 3 Nov 2019 12:48:25 +0100
Subject: [PATCH] cmake: set OpenGL_GL_PREFERENCE as a cached variable that can
 be modified via the command line

This allows the user to set this to LEGACY. This can be useful for
people under Linux using optirun/primusrun with "old" nvidia drivers
that don't support GLVND properly.
---
 CMakeLists.txt | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ecd6284edd..bc0176ba82 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -423,7 +423,8 @@ endif()
 include(CheckLib)
 include(CheckCXXSourceRuns)
 
-set(OpenGL_GL_PREFERENCE GLVND)
+set(OpenGL_GL_PREFERENCE GLVND CACHE STRING "Linux-only: if GLVND, use the vendor-neutral GL libraries (default). If LEGACY, use the legacy ones (might be necessary to have optirun/primusrun work)")
+set_property(CACHE OpenGL_GL_PREFERENCE PROPERTY STRINGS GLVND LEGACY)
 find_package(OpenGL)
 if (OPENGL_GL)
   include_directories(${OPENGL_INCLUDE_DIR})