Restore UnrefQueue to destruct animation asynchronously

components/sceneutil/unrefqueue.hpp

@@ -0,0 +1,36 @@
+#ifndef OPENMW_COMPONENTS_UNREFQUEUE_H
+#define OPENMW_COMPONENTS_UNREFQUEUE_H
+
+#include "workqueue.hpp"
+
+#include <osg/ref_ptr>
+#include <osg/Referenced>
+
+#include <vector>
+
+namespace SceneUtil
+{
+    class WorkQueue;
+
+    /// @brief Handles unreferencing of objects through the WorkQueue. Typical use scenario
+    /// would be the main thread pushing objects that are no longer needed, and the background thread deleting them.
+    class UnrefQueue
+    {
+    public:
+        /// Adds an object to the list of objects to be unreferenced. Call from the main thread.
+        void push(osg::ref_ptr<osg::Referenced>&& obj) { mObjects.push_back(std::move(obj)); }
+
+        void push(const osg::ref_ptr<osg::Referenced>& obj) { mObjects.push_back(obj); }
+
+        /// Adds a WorkItem to the given WorkQueue that will clear the list of objects in a worker thread,
+        /// thus unreferencing them. Call from the main thread.
+        void flush(SceneUtil::WorkQueue& workQueue);
+
+        std::size_t getSize() const { return mObjects.size(); }
+
+    private:
+        std::vector<osg::ref_ptr<osg::Referenced>> mObjects;
+    };
+}
+
+#endif