X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fevaluate.cpp;h=49dc07fe671ef0885ca9b5fbfd29a8fd2cc885ad;hb=50a7200b18e96a6f0e2c2ee7fda017ea6f2f1c1f;hp=984a85a65e0492c3daaa46ddc72f06709ae32487;hpb=496c7497cb81de4383f7df42b1836af53e432ce3;p=stockfish

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 984a85a6..49dc07fe 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -577,6 +577,18 @@ Value do_evaluate(const Position& pos, Value& margin) {
 
         mobility += MobilityBonus[Piece][mob];
 
+        // Add a bonus if a slider is pinning an enemy piece
+        if (   (Piece == BISHOP || Piece == ROOK || Piece == QUEEN)
+            && (PseudoAttacks[Piece][pos.king_square(Them)] & s))
+        {
+            b = BetweenBB[s][pos.king_square(Them)] & pos.pieces();
+
+            assert(b);
+
+            if (!more_than_one(b) && (b & pos.pieces(Them)))
+                score += ThreatBonus[Piece][type_of(pos.piece_on(lsb(b)))];
+        }
+
         // Decrease score if we are attacked by an enemy pawn. Remaining part
         // of threat evaluation must be done later when we have full attack info.
         if (ei.attackedBy[Them][PAWN] & s)
@@ -687,7 +699,8 @@ Value do_evaluate(const Position& pos, Value& margin) {
                       & ~ei.attackedBy[Them][0];
 
     if (undefendedMinors)
-        score += UndefendedMinorPenalty;
+        score += more_than_one(undefendedMinors) ? UndefendedMinorPenalty * 2
+                                                 : UndefendedMinorPenalty;
 
     // Enemy pieces not defended by a pawn and under our attack
     weakEnemies =  pos.pieces(Them)