Bonus for restricting opponent's piece moves

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index c7b9f894bf0b9a6f3e034eb90a815972b26becd7..f2126512413f576417faaed3bb08db28419afb3d 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -162,6 +162,7 @@ namespace {
   constexpr Score MinorBehindPawn    = S( 16,  0);
   constexpr Score Overload           = S( 12,  6);
   constexpr Score PawnlessFlank      = S( 18, 94);
+  constexpr Score RestrictedPiece    = S(  7,  6);
   constexpr Score RookOnPawn         = S( 10, 28);
   constexpr Score SliderOnQueen      = S( 49, 21);
   constexpr Score ThreatByKing       = S( 21, 84);
@@ -508,7 +509,7 @@ namespace {
     constexpr Direction Up       = (Us == WHITE ? NORTH   : SOUTH);
     constexpr Bitboard  TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
 
-    Bitboard b, weak, defended, nonPawnEnemies, stronglyProtected, safe;
+    Bitboard b, weak, defended, nonPawnEnemies, stronglyProtected, safe, restricted;
     Score score = SCORE_ZERO;
 
     // Non-pawn enemies
@@ -558,6 +559,13 @@ namespace {
         score += Overload * popcount(b);
     }
 
+    // Bonus for restricting their piece moves
+    restricted =   attackedBy[Them][ALL_PIECES]
+                & ~attackedBy[Them][PAWN]
+                & ~attackedBy2[Them]
+                &  attackedBy[Us][ALL_PIECES];
+    score += RestrictedPiece * popcount(restricted);
+
     // Bonus for enemy unopposed weak pawns
     if (pos.pieces(Us, ROOK, QUEEN))
         score += WeakUnopposedPawn * pe->weak_unopposed(Them);