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2022-10-20 20:29:11 +08:00
commit 4d531f8044
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+// SPDX-License-Identifier: LGPL-2.1-only
+// Copyright (C) 2021 James Hogan <james@albanarts.com>
+
+#ifndef OSGXR_FRAME_STAMPED_VECTOR
+#define OSGXR_FRAME_STAMPED_VECTOR 1
+
+#include <osg/FrameStamp>
+
+#include <optional>
+#include <utility>
+#include <vector>
+
+namespace osgXR {
+
+/**
+ * Manages frame stamping of vector items.
+ * Contains a vector of the chosen type, with each item stamped with a
+ * FrameStamp. Items can be retrieved by index or FrameStamp.
+ */
+template <typename T>
+class FrameStampedVector
+{
+    public:
+
+        typedef T Item;
+        typedef unsigned int FrameNumber;
+        typedef const osg::FrameStamp *Stamp;
+        typedef std::pair<Item, FrameNumber> StampedItem;
+
+        void reserve(unsigned int len)
+        {
+            _vec.reserve(len);
+        }
+
+        void resize(unsigned int len, Item item = Item())
+        {
+            _vec.resize(len, StampedItem(item, ~0));
+        }
+
+        unsigned int size() const
+        {
+            return _vec.size();
+        }
+
+        void push_back(const Item &item)
+        {
+            _vec.push_back(StampedItem(item, ~0));
+        }
+
+        // operator [] provides an Item if indexed directly
+        const Item &operator [] (unsigned int index) const
+        {
+            return _vec[index].first;
+        }
+
+        // operator [] provides an optional Item if indexed by stamp
+        std::optional<const Item> operator [] (Stamp stamp) const
+        {
+            int index = findStamp(stamp);
+            if (index < 0)
+                return std::nullopt;
+            return _vec[index].first;
+        }
+
+        int findStamp(Stamp stamp) const
+        {
+            unsigned int frameNumber = stamp->getFrameNumber();
+            for (unsigned int i = 0; i < _vec.size(); ++i)
+                if (_vec[i].second == frameNumber)
+                    return i;
+            return -1;
+        }
+
+        void setStamp(unsigned int index, Stamp stamp)
+        {
+            _vec[index].second = stamp->getFrameNumber();
+        }
+
+    protected:
+
+        std::vector<StampedItem> _vec;
+};
+
+}
+
+#endif