Simplify and improve the logic for passability calculations

src/fheroes2/gui/interface_gamearea.cpp

@@ -473,8 +473,6 @@ void Interface::GameArea::Redraw( fheroes2::Image & dst, int flag, bool isPuzzle
 
     TileUnfitRenderObjectInfo tileUnfit;
 
-    const Heroes * currentHero = drawHeroes ? GetFocusHeroes() : nullptr;
-
     // TODO: Dragon City with Object ICN Type OBJ_ICN_TYPE_OBJNMUL2 and object index 46 is a bottom layer sprite.
     // TODO: When a hero standing besides this turns a part of the hero is visible. This can be fixed only by some hack.
 
@@ -695,6 +693,8 @@ void Interface::GameArea::Redraw( fheroes2::Image & dst, int flag, bool isPuzzle
     // Draw hero's route. It should be drawn on top of everything.
     const bool drawRoutes = ( flag & LEVEL_ROUTES ) != 0;
 
+    const Heroes * currentHero = drawHeroes ? GetFocusHeroes() : nullptr;
+
     if ( drawRoutes && ( currentHero != nullptr ) && currentHero->GetPath().isShow() ) {
         const Route::Path & path = currentHero->GetPath();
         int32_t greenColorSteps = path.GetAllowedSteps();

src/fheroes2/maps/maps_tiles.cpp

@@ -254,6 +254,8 @@ namespace
         case MP2::OBJ_BARRIER:
         case MP2::OBJ_MAGIC_WELL:
         case MP2::OBJ_NOTHING_SPECIAL:
+        case MP2::OBJ_OASIS:
+        case MP2::OBJ_NON_ACTION_OASIS:
             return true;
         default:
             break;
@@ -694,6 +696,9 @@ void Maps::Tile::updatePassability()
         return;
     }
 
+    // If this assertion blows up then you are calling this method more than once!
+    assert( _tilePassabilityDirections == getTileIndependentPassability() );
+
     // Verify the neighboring tiles.
     // If a tile contains a tall object then it affects the passability of diagonal moves to the top from the current tile.
     if ( ( _tilePassabilityDirections & Direction::TOP_LEFT ) && isValidDirection( _index, Direction::LEFT ) ) {
@@ -712,26 +717,21 @@ void Maps::Tile::updatePassability()
         }
     }
 
-    // Get object type but ignore heroes as they are "temporary" objects.
-    const MP2::MapObjectType objectType = getMainObjectType( false );
-    if ( MP2::isOffGameActionObject( objectType ) ) {
-        // This is an action object. Action object passability is not affected by other objects.
-        return;
-    }
-
-    if ( isShadow() ) {
-        // The whole tile contains only shadow object parts. All shadows do not affect passability.
+    if ( getTileIndependentPassability() == DIRECTION_ALL ) {
+        // This tile is free of objects. Its passability must not be affected by any other objects.
+        //
+        // The original game does not consider this case and it is actually a bug
+        // as some tiles in the original game are marked inaccessible while no object exists on them.
         return;
     }
 
-    if ( _mainObjectPart.icnType == MP2::OBJ_ICN_TYPE_UNKNOWN ) {
-        // The main object part is not set. Ignore the tile.
-        // TODO: this is wrong as tiles can have object parts at the ground layer. Fix it!
-        return;
-    }
+    // If this assertion blows up then something is really off for the passability logic!
+    assert( !isShadow() && !isPassabilityTransparent() );
 
-    if ( _mainObjectPart.isPassabilityTransparent() ) {
-        // This object does not affect passability.
+    // Get object type but ignore heroes as they are "temporary" objects.
+    const MP2::MapObjectType objectType = getMainObjectType( false );
+    if ( MP2::isOffGameActionObject( objectType ) ) {
+        // This is an action object. Action object passability is not affected by other objects.
         return;
     }
 
@@ -772,6 +772,10 @@ void Maps::Tile::updatePassability()
         }
     }
 
+    // Even thought the passability of the tile below can be not blocked from the top,
+    // in the original game such a requirement is ignored.
+    // So, we have to follow the same logic.
+
     // Count how many objects are there excluding shadows, roads and river streams.
     const std::ptrdiff_t validBottomLayerObjects = std::count_if( _groundObjectPart.begin(), _groundObjectPart.end(), []( const auto & part ) {
         if ( isObjectPartShadow( part ) ) {
@@ -1041,7 +1045,7 @@ bool Maps::Tile::isPassabilityTransparent() const
         }
     }
 
-    return _mainObjectPart.isPassabilityTransparent();
+    return _mainObjectPart.icnType == MP2::OBJ_ICN_TYPE_UNKNOWN || _mainObjectPart.isPassabilityTransparent();
 }
 
 bool Maps::Tile::isPassableFrom( const int direction, const bool fromWater, const bool ignoreFog, const int heroColor ) const
@@ -1288,8 +1292,26 @@ void Maps::Tile::_updateRoadFlag()
     }
 }
 
-void Maps::Tile::fixMP2MapTileObjectType( Tile & tile )
+void Maps::Tile::fixMP2MapTileObjects( Tile & tile )
 {
+    const auto fixMandrakeObjectPart = []( Maps::ObjectPart & part ) {
+        if ( part.icnType != MP2::OBJ_ICN_TYPE_OBJNSWMP ) {
+            return;
+        }
+
+        if ( part.icnIndex == 131 || part.icnIndex == 137 ) {
+            part.layerType = Maps::OBJECT_LAYER;
+        }
+        else if ( part.icnIndex == 130 || part.icnIndex == 136 ) {
+            part.layerType = Maps::SHADOW_LAYER;
+        }
+    };
+
+    fixMandrakeObjectPart( tile.getMainObjectPart() );
+    for ( auto & part : tile.getGroundObjectParts() ) {
+        fixMandrakeObjectPart( part );
+    }
+
     const MP2::MapObjectType originalObjectType = tile.getMainObjectType( false );
 
     // Left tile of a skeleton on Desert should be marked as non-action tile.
@@ -1305,6 +1327,8 @@ void Maps::Tile::fixMP2MapTileObjectType( Tile & tile )
          && ( tile._mainObjectPart.icnIndex == 105 || tile._mainObjectPart.icnIndex == 106 ) ) {
         tile._topObjectPart.emplace_back();
         std::swap( tile._topObjectPart.back(), tile._mainObjectPart );
+        // Sorting ground object parts is a must after making the main object part empty!
+        tile.sortObjectParts();
 
         return;
     }

src/fheroes2/maps/maps_tiles.h

@@ -328,8 +328,8 @@ namespace Maps
             _fogDirection = fogDirection;
         }
 
-        // Some tiles have incorrect object type. This is due to original Editor issues.
-        static void fixMP2MapTileObjectType( Tile & tile );
+        // Some tiles have objects being set. This is due to original Editor issues.
+        static void fixMP2MapTileObjects( Tile & tile );
 
         static int32_t getIndexOfMainTile( const Tile & tile );
 

src/fheroes2/world/world_loadmap.cpp

@@ -1258,7 +1258,7 @@ bool World::loadResurrectionMap( const std::string & filename )
 bool World::ProcessNewMP2Map( const std::string & filename, const bool checkPoLObjects )
 {
     for ( Maps::Tile & tile : vec_tiles ) {
-        Maps::Tile::fixMP2MapTileObjectType( tile );
+        Maps::Tile::fixMP2MapTileObjects( tile );
 
         if ( !updateTileMetadata( tile, tile.getMainObjectType(), checkPoLObjects ) ) {
             ERROR_LOG( "Failed to load The Price of Loyalty map '" << filename << "' which is not supported by this version of the game." )