Bonus passed pawn blocked by our pieces

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index dedecfd16c73defa50fefb664189189cf8a898cd..5a28b286ae0a354c1f01eb6c445fb83fc85eaa13 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -160,7 +160,7 @@ namespace {
   const Score RookSemiopenFile = make_score(19, 10);
   const Score BishopPawns      = make_score( 8, 12);
   const Score MinorBehindPawn  = make_score(16,  0);
-  const Score TrappedRook      = make_score(90,  0);
+  const Score TrappedRook      = make_score(92,  0);
   const Score Unstoppable      = make_score( 0, 20);
 
   // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
@@ -350,7 +350,7 @@ namespace {
             if (   ((file_of(ksq) < FILE_E) == (file_of(s) < file_of(ksq)))
                 && (rank_of(ksq) == rank_of(s) || relative_rank(Us, ksq) == RANK_1)
                 && !ei.pi->semiopen_side(Us, file_of(ksq), file_of(s) < file_of(ksq)))
-                score -= (TrappedRook - make_score(mob * 8, 0)) * (1 + !pos.can_castle(Us));
+                score -= (TrappedRook - make_score(mob * 22, 0)) * (1 + !pos.can_castle(Us));
         }
 
         // An important Chess960 pattern: A cornered bishop blocked by a friendly
@@ -496,9 +496,17 @@ namespace {
 
     const Color Them = (Us == WHITE ? BLACK : WHITE);
 
-    Bitboard b, weakEnemies;
+    Bitboard b, weakEnemies, protectedEnemies;
     Score score = SCORE_ZERO;
 
+    // Protected enemies
+    protectedEnemies = (pos.pieces(Them) ^ pos.pieces(Them,PAWN))
+                      & ei.attackedBy[Them][PAWN]
+                      & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
+
+    if(protectedEnemies)
+        score += Threat[0][type_of(pos.piece_on(lsb(protectedEnemies)))];
+
     // Enemies not defended by a pawn and under our attack
     weakEnemies =  pos.pieces(Them)
                  & ~ei.attackedBy[Them][PAWN]
@@ -597,6 +605,8 @@ namespace {
 
                 mbonus += k * rr, ebonus += k * rr;
             }
+            else if(pos.pieces(Us) & blockSq)
+                mbonus += rr * 3 + r * 2 + 3, ebonus += rr + r * 2;
         } // rr != 0
 
         if (pos.count<PAWN>(Us) < pos.count<PAWN>(Them))
@@ -750,8 +760,10 @@ namespace {
                 // Endgame with opposite-colored bishops, but also other pieces. Still
                 // a bit drawish, but not as drawish as with only the two bishops.
                  sf = ScaleFactor(50 * sf / SCALE_FACTOR_NORMAL);
-        } else if ( ei.pi->pawn_span(strongSide) <= 1 &&
-                   !pos.pawn_passed(~strongSide, pos.king_square(~strongSide))) {
+        } else if (    abs(eg_value(score)) <= BishopValueEg
+                   &&  ei.pi->pawn_span(strongSide) <= 1
+                   && !pos.pawn_passed(~strongSide, pos.king_square(~strongSide))) {
+            // Endings where weaker side can be place his king in front of the opponent's pawns are drawish.
             sf = ScaleFactor(ScalePawnSpan[ei.pi->pawn_span(strongSide)]);
         }
     }