Allow to interrupt terrain preloading

apps/openmw/mwworld/cellpreloader.cpp

@@ -381,7 +381,7 @@ namespace MWWorld
         {
             for (unsigned int i=0; i<mTerrainViews.size() && i<mPreloadPositions.size() && !mAbort; ++i)
             {
-                mWorld->preload(mTerrainViews[i], mPreloadPositions[i]);
+                mWorld->preload(mTerrainViews[i], mPreloadPositions[i], mAbort);
                 mTerrainViews[i]->reset(0);
             }
         }

components/terrain/quadtreeworld.cpp

@@ -478,14 +478,14 @@ View* QuadTreeWorld::createView()
     return new ViewData;
 }
 
-void QuadTreeWorld::preload(View *view, const osg::Vec3f &eyePoint)
+void QuadTreeWorld::preload(View *view, const osg::Vec3f &eyePoint, std::atomic<bool> &abort)
 {
     ensureQuadTreeBuilt();
 
     ViewData* vd = static_cast<ViewData*>(view);
     traverse(mRootNode.get(), vd, nullptr, mRootNode->getLodCallback(), eyePoint, false);
 
-    for (unsigned int i=0; i<vd->getNumEntries(); ++i)
+    for (unsigned int i=0; i<vd->getNumEntries() && !abort; ++i)
     {
         ViewData::Entry& entry = vd->getEntry(i);
         loadRenderingNode(entry, vd, mVertexLodMod, mChunkManager.get());

components/terrain/quadtreeworld.hpp

@@ -30,7 +30,7 @@ namespace Terrain
         void cacheCell(View *view, int x, int y);
 
         View* createView();
-        void preload(View* view, const osg::Vec3f& eyePoint);
+        void preload(View* view, const osg::Vec3f& eyePoint, std::atomic<bool>& abort);
 
         void reportStats(unsigned int frameNumber, osg::Stats* stats);
 

components/terrain/world.hpp

@@ -5,6 +5,7 @@
 #include <osg/Referenced>
 #include <osg/Vec3f>
 
+#include <atomic>
 #include <memory>
 #include <set>
 
@@ -93,7 +94,7 @@ namespace Terrain
         virtual View* createView() { return nullptr; }
 
         /// @note Thread safe, as long as you do not attempt to load into the same view from multiple threads.
-        virtual void preload(View* view, const osg::Vec3f& eyePoint) {}
+        virtual void preload(View* view, const osg::Vec3f& eyePoint, std::atomic<bool>& abort) {}
 
         virtual void reportStats(unsigned int frameNumber, osg::Stats* stats) {}