From daf1a40521f51ccab5f9188b458b3a41abb0bbf4 Mon Sep 17 00:00:00 2001
From: Christoph Oelckers <coelckers@zdoom.fake>
Date: Sat, 3 Dec 2016 20:09:25 +0100
Subject: [PATCH] - allow swapping the order of gl_finish and SwapBuffers
 calls, because some cards do not seem to like the correct order.

---
 src/gl/system/gl_framebuffer.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/gl/system/gl_framebuffer.cpp b/src/gl/system/gl_framebuffer.cpp
index 7102df72e..f20c9e502 100644
--- a/src/gl/system/gl_framebuffer.cpp
+++ b/src/gl/system/gl_framebuffer.cpp
@@ -207,17 +207,20 @@ void OpenGLFrameBuffer::Update()
 //
 //==========================================================================
 
+CVAR(Bool, gl_finishbeforeswap, false, 0);
+
 void OpenGLFrameBuffer::Swap()
 {
 	Finish.Reset();
 	Finish.Clock();
-	if (needsetgamma) 
+	if (gl_finishbeforeswap) glFinish();
+	if (needsetgamma)
 	{
 		//DoSetGamma();
 		needsetgamma = false;
 	}
 	SwapBuffers();
-	glFinish();
+	if (!gl_finishbeforeswap) glFinish();
 	Finish.Unclock();
 	swapped = true;
 	FHardwareTexture::UnbindAll();