From f504ab42feb40382228390b4b3a62874303b3de0 Mon Sep 17 00:00:00 2001
From: scrawl <scrawl@baseoftrash.de>
Date: Sun, 13 Oct 2013 17:52:14 +0200
Subject: [PATCH] Turn off vsync while in the loading screen

---
 apps/openmw/mwgui/loadingscreen.cpp | 22 +++++++++++++++++++++-
 apps/openmw/mwgui/loadingscreen.hpp |  2 ++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/apps/openmw/mwgui/loadingscreen.cpp b/apps/openmw/mwgui/loadingscreen.cpp
index 9b63dfa76d..d2ebcd109d 100644
--- a/apps/openmw/mwgui/loadingscreen.cpp
+++ b/apps/openmw/mwgui/loadingscreen.cpp
@@ -23,6 +23,7 @@ namespace MWGui
         , mLastWallpaperChangeTime(0.f)
         , mFirstLoad(true)
         , mProgress(0)
+        , mVSyncWasEnabled(false)
     {
         getWidget(mLoadingText, "LoadingText");
         getWidget(mProgressBar, "ProgressBar");
@@ -67,6 +68,14 @@ namespace MWGui
 
     void LoadingScreen::loadingOn()
     {
+        // Temporarily turn off VSync, we want to do actual loading rather than waiting for the screen to sync.
+        // Threaded loading would be even better, of course - especially because some drivers force VSync to on and we can't change it.
+        // In Ogre 1.8, the swapBuffers argument is useless and setVSyncEnabled is bugged with GLX, nothing we can do :/
+        mVSyncWasEnabled = mWindow->isVSyncEnabled();
+        #if OGRE_VERSION >= (1 << 16 | 9 << 8 | 0)
+        mWindow->setVSyncEnabled(false);
+        #endif
+
         setVisible(true);
 
         if (mFirstLoad)
@@ -83,6 +92,12 @@ namespace MWGui
 
     void LoadingScreen::loadingOff()
     {
+        // Re-enable vsync now.
+        // In Ogre 1.8, the swapBuffers argument is useless and setVSyncEnabled is bugged with GLX, nothing we can do :/
+        #if OGRE_VERSION >= (1 << 16 | 9 << 8 | 0)
+        mWindow->setVSyncEnabled(mVSyncWasEnabled);
+        #endif
+
         setVisible(false);
 
         MWBase::Environment::get().getWindowManager()->removeGuiMode(GM_Loading);
@@ -212,7 +227,12 @@ namespace MWGui
             // caused a sync / flush and would be expensive).
             // We're doing this so we can do some actual loading while the GPU is busy with the render.
             // This means the render is lagging a frame behind, but this is hardly noticable.
-            mWindow->swapBuffers(false); // never Vsync, makes no sense here
+#if OGRE_VERSION >= (1 << 16 | 9 << 8 | 0)
+            mWindow->swapBuffers();
+#else
+            // In Ogre 1.8, the swapBuffers argument is useless and setVSyncEnabled is bugged when using GLX. Not much we can do :/
+            mWindow->swapBuffers(false);
+#endif
             mWindow->update(false);
 
             if (!hasCompositor)
diff --git a/apps/openmw/mwgui/loadingscreen.hpp b/apps/openmw/mwgui/loadingscreen.hpp
index dde8ff63aa..2d1d7431f8 100644
--- a/apps/openmw/mwgui/loadingscreen.hpp
+++ b/apps/openmw/mwgui/loadingscreen.hpp
@@ -57,6 +57,8 @@ namespace MWGui
 
         Ogre::StringVector mResources;
 
+        bool mVSyncWasEnabled;
+
         void changeWallpaper();
 
         void draw();