Bug #1109: Do not reset water level when loading a plugin with no water level record (for real this time)

apps/openmw/mwworld/store.cpp

@@ -56,7 +56,7 @@ void Store<ESM::Cell>::load(ESM::ESMReader &esm, const std::string &id)
             // copy list into new cell
             cell->mContextList = oldcell->mContextList;
             // have new cell replace old cell
-            *oldcell = *cell;
+            ESM::Cell::merge(oldcell, cell);
         } else
             mInt[idLower] = *cell;
     }
@@ -83,7 +83,7 @@ void Store<ESM::Cell>::load(ESM::ESMReader &esm, const std::string &id)
             }
             cell->mMovedRefs = oldcell->mMovedRefs;
             // have new cell replace old cell
-            *oldcell = *cell;
+            ESM::Cell::merge(oldcell, cell);
         } else
             mExt[std::make_pair(cell->mData.mX, cell->mData.mY)] = *cell;
     }

components/esm/loadcell.cpp

@@ -47,9 +47,13 @@ void Cell::load(ESMReader &esm, bool saveContext)
             esm.getHT(waterl);
             mWater = (float) waterl;
             mWaterInt = true;
+            mHasWaterLevelRecord = true;
         }
         else if (esm.isNextSub("WHGT"))
+        {
             esm.getHT(mWater);
+            mHasWaterLevelRecord = true;
+        }
 
         // Quasi-exterior cells have a region (which determines the
         // weather), pure interior cells have ambient lighting
@@ -94,7 +98,7 @@ void Cell::save(ESMWriter &esm) const
     esm.writeHNT("DATA", mData, 12);
     if (mData.mFlags & Interior)
     {
-        if (mWater != -1) {
+        if (mHasWaterLevelRecord) {
             if (mWaterInt) {
                 int water =
                     (mWater >= 0) ? (int) (mWater + 0.5) : (int) (mWater - 0.5);
@@ -301,4 +305,17 @@ bool Cell::getNextMVRF(ESMReader &esm, MovedCellRef &mref)
         mAmbi.mFog = 0;
         mAmbi.mFogDensity = 0;
     }
+
+    void Cell::merge(Cell *original, Cell *modified)
+    {
+        float waterLevel = original->mWater;
+        if (modified->mHasWaterLevelRecord)
+        {
+            waterLevel = modified->mWater;
+        }
+        // else: keep original water level, instead of resetting to 0
+
+        *original = *modified;
+        original->mWater = waterLevel;
+    }
 }

components/esm/loadcell.hpp

@@ -77,7 +77,10 @@ struct Cell
     float mFogDensity;
   };
 
-  Cell() : mWater(-1) {}
+  Cell() : mWater(0), mHasWaterLevelRecord(false) {}
+
+  /// Merge \a modified into \a original
+  static void merge (Cell* original, Cell* modified);
 
   // Interior cells are indexed by this (it's the 'id'), for exterior
   // cells it is optional.
@@ -90,6 +93,7 @@ struct Cell
   DATAstruct mData;
   AMBIstruct mAmbi;
   float mWater; // Water level
+  bool mHasWaterLevelRecord;
   bool mWaterInt;
   int mMapColor;
   int mNAM0;