Retain final draw callback as a member variable in ScreenshotManager, and do not call setFinalDrawCallback after init.

apps/openmw/mwrender/screenshotmanager.cpp

@@ -36,8 +36,8 @@ namespace MWRender
     class NotifyDrawCompletedCallback : public osg::Camera::DrawCallback
     {
     public:
-        NotifyDrawCompletedCallback(unsigned int frame)
+        NotifyDrawCompletedCallback()
-            : mDone(false), mFrame(frame)
+            : mDone(false), mFrame(0)
         {
         }
 
@@ -59,6 +59,12 @@ namespace MWRender
             mCondition.wait(lock);
         }
 
+        void reset(unsigned int frame)
+        {
+            mDone = false;
+            mFrame = frame;
+        }
+
         mutable std::condition_variable mCondition;
         mutable std::mutex mMutex;
         mutable bool mDone;
@@ -94,8 +100,18 @@ namespace MWRender
         : mViewer(viewer)
         , mRootNode(rootNode)
         , mSceneRoot(sceneRoot)
+        , mDrawCompleteCallback(new NotifyDrawCompletedCallback)
         , mResourceSystem(resourceSystem)
         , mWater(water)
+    {
+        // Note: This assumes no other final draw callbacks are set anywhere and that this callback will remain set until the application exits.
+        // This works around *DrawCallback manipulation being unsafe in OSG >= 3.5.10 for release 0.47
+        // If you need to set other final draw callbacks, read the comments of issue 6013 for a suggestion
+        // Ref https://gitlab.com/OpenMW/openmw/-/issues/6013
+        mViewer->getCamera()->setFinalDrawCallback(mDrawCompleteCallback);
+    }
+
+    ScreenshotManager::~ScreenshotManager()
     {
     }
 
@@ -107,16 +123,10 @@ namespace MWRender
         tempDrw->setCullingActive(false);
         tempDrw->getOrCreateStateSet()->setRenderBinDetails(100, "RenderBin", osg::StateSet::USE_RENDERBIN_DETAILS); // so its after all scene bins but before POST_RENDER gui camera
         camera->addChild(tempDrw);
-        osg::ref_ptr<NotifyDrawCompletedCallback> callback (new NotifyDrawCompletedCallback(mViewer->getFrameStamp()->getFrameNumber()));
+        traversalsAndWait(mViewer->getFrameStamp()->getFrameNumber());
-        camera->setFinalDrawCallback(callback);
-        mViewer->eventTraversal();
-        mViewer->updateTraversal();
-        mViewer->renderingTraversals();
-        callback->waitTillDone();
         // now that we've "used up" the current frame, get a fresh frame number for the next frame() following after the screenshot is completed
         mViewer->advance(mViewer->getFrameStamp()->getSimulationTime());
         camera->removeChild(tempDrw);
-        camera->setFinalDrawCallback(nullptr);
     }
 
     bool ScreenshotManager::screenshot360(osg::Image* image)
@@ -257,6 +267,15 @@ namespace MWRender
         return true;
     }
 
+    void ScreenshotManager::traversalsAndWait(unsigned int frame)
+    {
+        mDrawCompleteCallback->reset(frame);
+        mViewer->eventTraversal();
+        mViewer->updateTraversal();
+        mViewer->renderingTraversals();
+        mDrawCompleteCallback->waitTillDone();
+    }
+
     void ScreenshotManager::renderCameraToImage(osg::Camera *camera, osg::Image *image, int w, int h)
     {
         camera->setNodeMask(Mask_RenderToTexture);
@@ -280,16 +299,10 @@ namespace MWRender
 
         mRootNode->addChild(camera);
 
-        // The draw needs to complete before we can copy back our image.
-        osg::ref_ptr<NotifyDrawCompletedCallback> callback (new NotifyDrawCompletedCallback(0));
-        camera->setFinalDrawCallback(callback);
-
         MWBase::Environment::get().getWindowManager()->getLoadingScreen()->loadingOn(false);
 
-        mViewer->eventTraversal();
+        // The draw needs to complete before we can copy back our image.
-        mViewer->updateTraversal();
+        traversalsAndWait(0);
-        mViewer->renderingTraversals();
-        callback->waitTillDone();
 
         MWBase::Environment::get().getWindowManager()->getLoadingScreen()->loadingOff();
 

apps/openmw/mwrender/screenshotmanager.hpp

@@ -16,11 +16,13 @@ namespace Resource
 namespace MWRender
 {
     class Water;
+    class NotifyDrawCompletedCallback;
 
     class ScreenshotManager
     {
     public:
         ScreenshotManager(osgViewer::Viewer* viewer, osg::ref_ptr<osg::Group> rootNode, osg::ref_ptr<osg::Group> sceneRoot, Resource::ResourceSystem* resourceSystem, Water* water);
+        ~ScreenshotManager();
 
         void screenshot(osg::Image* image, int w, int h);
         bool screenshot360(osg::Image* image);
@@ -29,9 +31,11 @@ namespace MWRender
         osg::ref_ptr<osgViewer::Viewer> mViewer;
         osg::ref_ptr<osg::Group> mRootNode;
         osg::ref_ptr<osg::Group> mSceneRoot;
+        osg::ref_ptr<NotifyDrawCompletedCallback> mDrawCompleteCallback;
         Resource::ResourceSystem* mResourceSystem;
         Water* mWater;
 
+        void traversalsAndWait(unsigned int frame);
         void renderCameraToImage(osg::Camera *camera, osg::Image *image, int w, int h);
         void makeCubemapScreenshot(osg::Image* image, int w, int h, osg::Matrixd cameraTransform=osg::Matrixd());
     };