Attack threats

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 39dac6d14ffb5481b74986ec41660cf5aebac6f0..e10618494cc1c87a1af02a64909be59af6c78b16 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -211,23 +211,24 @@ namespace {
   const Score KingProtector[] = { S(-3, -5), S(-4, -3), S(-3, 0), S(-1, 1) };
 
   // Assorted bonuses and penalties used by evaluation
-  const Score MinorBehindPawn     = S( 16,  0);
-  const Score BishopPawns         = S(  8, 12);
-  const Score LongRangedBishop    = S( 22,  0);
-  const Score RookOnPawn          = S(  8, 24);
-  const Score TrappedRook         = S( 92,  0);
-  const Score WeakQueen           = S( 50, 10);
-  const Score OtherCheck          = S( 10, 10);
-  const Score CloseEnemies        = S(  7,  0);
-  const Score PawnlessFlank       = S( 20, 80);
-  const Score ThreatByHangingPawn = S( 71, 61);
-  const Score ThreatBySafePawn    = S(192,175);
-  const Score ThreatByRank        = S( 16,  3);
-  const Score Hanging             = S( 48, 27);
-  const Score WeakUnopposedPawn   = S(  5, 25);
-  const Score ThreatByPawnPush    = S( 38, 22);
-  const Score HinderPassedPawn    = S(  7,  0);
-  const Score TrappedBishopA1H1   = S( 50, 50);
+  const Score MinorBehindPawn       = S( 16,  0);
+  const Score BishopPawns           = S(  8, 12);
+  const Score LongRangedBishop      = S( 22,  0);
+  const Score RookOnPawn            = S(  8, 24);
+  const Score TrappedRook           = S( 92,  0);
+  const Score WeakQueen             = S( 50, 10);
+  const Score OtherCheck            = S( 10, 10);
+  const Score CloseEnemies          = S(  7,  0);
+  const Score PawnlessFlank         = S( 20, 80);
+  const Score ThreatByHangingPawn   = S( 71, 61);
+  const Score ThreatBySafePawn      = S(192,175);
+  const Score ThreatByRank          = S( 16,  3);
+  const Score Hanging               = S( 48, 27);
+  const Score WeakUnopposedPawn     = S(  5, 25);
+  const Score ThreatByPawnPush      = S( 38, 22);
+  const Score ThreatByAttackOnQueen = S( 38, 22);
+  const Score HinderPassedPawn      = S(  7,  0);
+  const Score TrappedBishopA1H1     = S( 50, 50);
 
   #undef S
   #undef V
@@ -303,6 +304,9 @@ namespace {
 
     attackedBy[Us][Pt] = 0;
 
+    if (Pt == QUEEN)
+        attackedBy[Us][QUEEN_DIAGONAL] = 0;
+
     while ((s = *pl++) != SQ_NONE)
     {
         // Find attacked squares, including x-ray attacks for bishops and rooks
@@ -316,6 +320,9 @@ namespace {
         attackedBy2[Us] |= attackedBy[Us][ALL_PIECES] & b;
         attackedBy[Us][ALL_PIECES] |= attackedBy[Us][Pt] |= b;
 
+        if (Pt == QUEEN)
+            attackedBy[Us][QUEEN_DIAGONAL] |= b & PseudoAttacks[BISHOP][s];
+
         if (b & kingRing[Them])
         {
             kingAttackersCount[Us]++;
@@ -609,6 +616,13 @@ namespace {
 
     score += ThreatByPawnPush * popcount(b);
 
+    // Add a bonus for safe slider attack threats on opponent queen
+    safeThreats = ~pos.pieces(Us) & ~attackedBy2[Them] & attackedBy2[Us];
+    b =  (attackedBy[Us][BISHOP] & attackedBy[Them][QUEEN_DIAGONAL])
+       | (attackedBy[Us][ROOK  ] & attackedBy[Them][QUEEN] & ~attackedBy[Them][QUEEN_DIAGONAL]);
+
+    score += ThreatByAttackOnQueen * popcount(b & safeThreats);
+
     if (T)
         Trace::add(THREAT, Us, score);