stop reporting changes originating from physics system back to physics system

apps/openmw/CMakeLists.txt

@@ -125,6 +125,7 @@ set(GAMEWORLD
     mwworld/actiontake.cpp
     mwworld/containerutil.cpp
     mwworld/player.cpp
+    mwworld/doingphysics.cpp
     )
 set(GAMEWORLD_HEADER
     mwworld/refdata.hpp
@@ -143,6 +144,7 @@ set(GAMEWORLD_HEADER
     mwworld/manualref.hpp
     mwworld/containerutil.hpp
     mwworld/player.hpp
+    mwworld/doingphysics.hpp
     )
 source_group(apps\\openmw\\mwworld FILES ${GAMEWORLD} ${GAMEWORLD_HEADER})
 

apps/openmw/mwrender/mwscene.cpp

@@ -11,6 +11,7 @@
 
 #include "../mwworld/world.hpp" // these includes can be removed once the static-hack is gone
 #include "../mwworld/ptr.hpp"
+#include "../mwworld/doingphysics.hpp"
 #include <components/esm/loadstat.hpp>
 
 #include "player.hpp"
@@ -100,6 +101,8 @@ std::pair<std::string, float> MWScene::getFacedHandle (MWWorld::World& world)
 
 void MWScene::doPhysics (float duration, MWWorld::World& world)
 {
+    // stop changes to world from being reported back to the physics system
+    MWWorld::DoingPhysics scopeGuard;
 
 }
 

apps/openmw/mwworld/doingphysics.cpp

@@ -0,0 +1,22 @@
+
+#include "doingphysics.hpp"
+
+namespace MWWorld
+{
+    int DoingPhysics::sCounter = 0;
+
+    DoingPhysics::DoingPhysics()
+    {
+        ++sCounter;
+    }
+
+    DoingPhysics::~DoingPhysics()
+    {
+        --sCounter;
+    }
+
+    bool DoingPhysics::isDoingPhysics()
+    {
+        return sCounter>0;
+    }
+}

apps/openmw/mwworld/doingphysics.hpp

@@ -0,0 +1,26 @@
+#ifndef GAME_MWWORLD_DOINGPHYSICS_H
+#define GAME_MWWORLD_DOINGPHYSICS_H
+
+namespace MWWorld
+{
+    ///< Scope guard for blocking physics updates during physics simulation.
+    class DoingPhysics
+    {
+            static int sCounter;
+
+        private:
+
+            DoingPhysics (const DoingPhysics&);
+            DoingPhysics& operator= (const DoingPhysics&);
+
+        public:
+
+            DoingPhysics();
+
+            ~DoingPhysics();
+
+            static bool isDoingPhysics();
+    };
+}
+
+#endif