merge redundant input events

components/sdlutil/sdlinputwrapper.cpp

@@ -49,17 +49,42 @@ InputWrapper::InputWrapper(SDL_Window* window, osg::ref_ptr<osgViewer::Viewer> v
 
         SDL_PumpEvents();
 
-        SDL_Event evt;
+        SDL_Event event;
 
         if (windowEventsOnly)
         {
             // During loading, just handle window events, and keep others for later
-            while (SDL_PeepEvents(&evt, 1, SDL_GETEVENT, SDL_WINDOWEVENT, SDL_WINDOWEVENT))
-                handleWindowEvent(evt);
+            while (SDL_PeepEvents(&event, 1, SDL_GETEVENT, SDL_WINDOWEVENT, SDL_WINDOWEVENT))
+                handleWindowEvent(event);
             return;
         }
 
-        while(SDL_PollEvent(&evt))
+        // Merge redundant events to avoid unnecessary listener calls
+        std::vector<SDL_Event> events;
+        while(SDL_PollEvent(&event)) {
+            if (events.empty() || events.back().type != event.type)
+            {
+                events.emplace_back(event);
+                continue;
+            }
+
+            SDL_Event& previousEvent = events.back();
+
+            switch (event.type)
+            {
+                case SDL_MOUSEMOTION:
+                    previousEvent.motion.x = event.motion.x;
+                    previousEvent.motion.y = event.motion.y;
+                    previousEvent.motion.xrel += event.motion.xrel;
+                    previousEvent.motion.yrel += event.motion.yrel;
+                    break;
+                default:
+                    events.emplace_back(event);
+            }
+        }
+
+
+        for (const SDL_Event& evt : events)
         {
             switch(evt.type)
             {