From 96a87b582c41f2c83a373a019a776a5ec16f1b6e Mon Sep 17 00:00:00 2001
From: psi29a <psi29a@gmail.com>
Date: Thu, 17 Dec 2020 22:51:04 +0000
Subject: [PATCH] Merge branch 'loadingScreen_initialdrawcallback' into
 'master'

Fix for !472 for older versions of OSG

See merge request OpenMW/openmw!474

(cherry picked from commit 35e25d79b9a6c76807084be5ca2584c4fd9b9c35)

4447dd41 osg versions
06f4d63b Preserve callback in older osg version
---
 apps/openmw/mwgui/loadingscreen.cpp | 14 ++++++++++++++
 apps/openmw/mwgui/loadingscreen.hpp |  2 ++
 2 files changed, 16 insertions(+)

diff --git a/apps/openmw/mwgui/loadingscreen.cpp b/apps/openmw/mwgui/loadingscreen.cpp
index 20586ef4af..9ab5e32a3f 100644
--- a/apps/openmw/mwgui/loadingscreen.cpp
+++ b/apps/openmw/mwgui/loadingscreen.cpp
@@ -5,6 +5,7 @@
 #include <osgViewer/Viewer>
 
 #include <osg/Texture2D>
+#include <osg/Version>
 
 #include <MyGUI_RenderManager.h>
 #include <MyGUI_ScrollBar.h>
@@ -43,6 +44,7 @@ namespace MWGui
         , mNestedLoadingCount(0)
         , mProgress(0)
         , mShowWallpaper(true)
+        , mOldCallback(nullptr)
     {
         mMainWidget->setSize(MyGUI::RenderManager::getInstance().getViewSize());
 
@@ -322,7 +324,13 @@ namespace MWGui
             mCopyFramebufferToTextureCallback = new CopyFramebufferToTextureCallback(mTexture);
         }
 
+#if OSG_VERSION_GREATER_OR_EQUAL(3, 5, 10)
         mViewer->getCamera()->addInitialDrawCallback(mCopyFramebufferToTextureCallback);
+#else
+        // TODO: Remove once we officially end support for OSG versions pre 3.5.10
+        mOldCallback = mViewer->getCamera()->getInitialDrawCallback();
+        mViewer->getCamera()->setInitialDrawCallback(mCopyFramebufferToTextureCallback);
+#endif
 
         mBackgroundImage->setBackgroundImage("");
         mBackgroundImage->setVisible(false);
@@ -367,7 +375,13 @@ namespace MWGui
 
         if (mCopyFramebufferToTextureCallback)
         {
+            
+#if OSG_VERSION_GREATER_OR_EQUAL(3, 5, 10)
             mViewer->getCamera()->removeInitialDrawCallback(mCopyFramebufferToTextureCallback);
+#else
+            // TODO: Remove once we officially end support for OSG versions pre 3.5.10
+            mViewer->getCamera()->setInitialDrawCallback(mOldCallback);
+#endif
             mCopyFramebufferToTextureCallback = nullptr;
         }
 
diff --git a/apps/openmw/mwgui/loadingscreen.hpp b/apps/openmw/mwgui/loadingscreen.hpp
index ac911ab60b..d58899eae4 100644
--- a/apps/openmw/mwgui/loadingscreen.hpp
+++ b/apps/openmw/mwgui/loadingscreen.hpp
@@ -3,6 +3,7 @@
 
 #include <memory>
 
+#include <osg/Camera>
 #include <osg/Timer>
 #include <osg/ref_ptr>
 
@@ -86,6 +87,7 @@ namespace MWGui
 
         osg::ref_ptr<osg::Texture2D> mTexture;
         osg::ref_ptr<CopyFramebufferToTextureCallback> mCopyFramebufferToTextureCallback;
+        osg::ref_ptr<osg::Camera::DrawCallback> mOldCallback;
         std::unique_ptr<MyGUI::ITexture> mGuiTexture;
 
         void changeWallpaper();