Correct Outflanking calculations in classical eval

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index dd5d23b253dd074a0feef432367a899d9dc1e1b3..7671f6052df6050c7d2d21d84dcf173472658c5b 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -791,11 +791,13 @@ namespace {
                     unsafeSquares &= attackedBy[Them][ALL_PIECES] | pos.pieces(Them);
 
                 // If there are no enemy pieces or attacks on passed pawn span, assign a big bonus.
+                // Or if there is some, but they are all attacked by our pawns, assign a bit smaller bonus.
                 // Otherwise assign a smaller bonus if the path to queen is not attacked
                 // and even smaller bonus if it is attacked but block square is not.
-                int k = !unsafeSquares                    ? 35 :
-                        !(unsafeSquares & squaresToQueen) ? 20 :
-                        !(unsafeSquares & blockSq)        ?  9 :
+                int k = !unsafeSquares                    ? 36 :
+                !(unsafeSquares & ~attackedBy[Us][PAWN])  ? 30 :
+                        !(unsafeSquares & squaresToQueen) ? 17 :
+                        !(unsafeSquares & blockSq)        ?  7 :
                                                              0 ;
 
                 // Assign a larger bonus if the block square is defended
@@ -865,7 +867,7 @@ namespace {
   Value Evaluation<T>::winnable(Score score) const {
 
     int outflanking =  distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK))
-                     - distance<Rank>(pos.square<KING>(WHITE), pos.square<KING>(BLACK));
+                    + int(rank_of(pos.square<KING>(WHITE)) - rank_of(pos.square<KING>(BLACK)));
 
     bool pawnsOnBothFlanks =   (pos.pieces(PAWN) & QueenSide)
                             && (pos.pieces(PAWN) & KingSide);