Simplify connected pawn scoring

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index ad76fc8d727b145e5815cafcc44e5f1e094cbc47..9521cd100282487f44ba3926f01afde124797bc6 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -169,7 +169,7 @@ namespace {
     template<Color Us> Score passed() const;
     template<Color Us> Score space() const;
     ScaleFactor scale_factor(Value eg) const;
-    Score initiative(Value eg) const;
+    Score initiative(Score score) const;
 
     const Position& pos;
     Material::Entry* me;
@@ -353,7 +353,7 @@ namespace {
 
             // Bonus for rook on an open or semi-open file
             if (pos.is_on_semiopen_file(Us, s))
-                score += RookOnFile[bool(pos.is_on_semiopen_file(Them, s))];
+                score += RookOnFile[pos.is_on_semiopen_file(Them, s)];
 
             // Penalty when trapped by the king, even more if the king cannot castle
             else if (mob <= 3)
@@ -717,7 +717,10 @@ namespace {
   // known attacking/defending status of the players.
 
   template<Tracing T>
-  Score Evaluation<T>::initiative(Value eg) const {
+  Score Evaluation<T>::initiative(Score score) const {
+
+    Value mg = mg_value(score);
+    Value eg = eg_value(score);
 
     int outflanking =  distance<File>(pos.square<KING>(WHITE), pos.square<KING>(BLACK))
                      - distance<Rank>(pos.square<KING>(WHITE), pos.square<KING>(BLACK));
@@ -738,15 +741,16 @@ namespace {
                     - 36 * almostUnwinnable
                     -103 ;
 
-    // Now apply the bonus: note that we find the attacking side by extracting
-    // the sign of the endgame value, and that we carefully cap the bonus so
-    // that the endgame score will never change sign after the bonus.
+    // Now apply the bonus: note that we find the attacking side by extracting the
+    // sign of the midgame or endgame values, and that we carefully cap the bonus
+    // so that the midgame and endgame scores do not change sign after the bonus.
+    int u = ((mg > 0) - (mg < 0)) * std::max(std::min(complexity + 50, 0), -abs(mg));
     int v = ((eg > 0) - (eg < 0)) * std::max(complexity, -abs(eg));
 
     if (T)
-        Trace::add(INITIATIVE, make_score(0, v));
+        Trace::add(INITIATIVE, make_score(u, v));
 
-    return make_score(0, v);
+    return make_score(u, v);
   }
 
 
@@ -765,8 +769,9 @@ namespace {
             && pos.non_pawn_material() == 2 * BishopValueMg)
             sf = 16 + 4 * pe->passed_count();
         else
-            sf = std::min(40 + (pos.opposite_bishops() ? 2 : 7) * pos.count<PAWN>(strongSide), sf);
+            sf = std::min(sf, 36 + (pos.opposite_bishops() ? 2 : 7) * pos.count<PAWN>(strongSide));
 
+        sf = std::max(0, sf - (pos.rule50_count() - 12) / 4  );
     }
 
     return ScaleFactor(sf);
@@ -822,7 +827,7 @@ namespace {
             + passed< WHITE>() - passed< BLACK>()
             + space<  WHITE>() - space<  BLACK>();
 
-    score += initiative(eg_value(score));
+    score += initiative(score);
 
     // Interpolate between a middlegame and a (scaled by 'sf') endgame score
     ScaleFactor sf = scale_factor(eg_value(score));