first commit

3rdparty/osgXR/src/FrameStore.cpp

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+// SPDX-License-Identifier: LGPL-2.1-only
+// Copyright (C) 2021 James Hogan <james@albanarts.com>
+
+#include "FrameStore.h"
+
+#include <osg/FrameStamp>
+
+#include <cassert>
+
+using namespace osgXR;
+
+FrameStore::FrameStore()
+{
+}
+
+osg::ref_ptr<FrameStore::Frame> FrameStore::getFrame(FrameStore::Stamp stamp)
+{
+    OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_mutex);
+
+    int index = lookupFrame(stamp);
+    if (index < 0)
+        return nullptr;
+
+    return _store[index];
+}
+
+osg::ref_ptr<FrameStore::Frame> FrameStore::getFrame(FrameStore::Stamp stamp,
+                                                     OpenXR::Session *session)
+{
+    OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_mutex);
+
+    int index = lookupFrame(stamp);
+    if (index < 0)
+    {
+        index = blankFrame();
+        // there surely shouldn't be more than 2 frames in parallel
+        assert(index >= 0);
+        if (index < 0)
+            return nullptr;
+
+        osg::ref_ptr<OpenXR::Session::Frame> frame = session->waitFrame();
+        if (frame.valid())
+        {
+            frame->setOsgFrameNumber(stamp->getFrameNumber());
+            _store[index] = frame;
+        }
+        return frame;
+    }
+
+    return _store[index];
+}
+
+bool FrameStore::endFrame(FrameStore::Stamp stamp)
+{
+    OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_mutex);
+
+    int index = lookupFrame(stamp);
+    if (index < 0)
+        return false;
+
+    _store[index]->end();
+    _store[index] = nullptr;
+
+    return true;
+}
+
+int FrameStore::lookupFrame(FrameStore::Stamp stamp) const
+{
+    unsigned int frameNumber = stamp->getFrameNumber();
+    for (unsigned int i = 0; i < maxFrames; ++i)
+    {
+        if (_store[i].valid() &&
+            _store[i]->getOsgFrameNumber() == frameNumber)
+        {
+            return i;
+        }
+    }
+    return -1;
+}
+
+int FrameStore::blankFrame() const
+{
+    for (unsigned int i = 0; i < maxFrames; ++i)
+        if (!_store[i].valid())
+            return i;
+    return -1;
+}