Bishop pins only

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 49dc07fe671ef0885ca9b5fbfd29a8fd2cc885ad..183f166a8e3c8b1e37ffe91188c0858a8a6e4cd1 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -577,22 +577,15 @@ 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)
             score -= ThreatenedByPawnPenalty[Piece];
+        else if (Piece == BISHOP && (PseudoAttacks[Piece][pos.king_square(Them)] & s)) {
+             const Bitboard between = BetweenBB[s][pos.king_square(Them)] & pos.pieces();
+             if (!more_than_one(between))
+                 score += make_score(15, 25);
+        }
 
         // Bishop and knight outposts squares
         if (    (Piece == BISHOP || Piece == KNIGHT)