From: mbootsector <mbootsector@gmail.com>
Date: Fri, 25 Nov 2016 16:47:18 +0000 (+0100)
Subject: Rank based threats
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=e7289465b9ecb2ab93b240285f8ab677eea86aeb;hp=8ceb1ff53bf4b9aa9609d39f11bcb540a70ce4a5

Rank based threats

STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 19404 W: 3581 L: 3374 D: 12449

LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 16204 W: 2194 L: 2023 D: 11987

Bench: 5757843
---

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 434ebd62..8987b0ec 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -200,6 +200,7 @@ namespace {
   const Score Unstoppable         = S( 0, 20);
   const Score PawnlessFlank       = S(20, 80);
   const Score HinderPassedPawn    = S( 7,  0);
+  const Score ThreatByRank        = S(16,  3);
 
   // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
   // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
@@ -561,11 +562,21 @@ namespace {
     {
         b = (defended | weak) & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
         while (b)
-            score += Threat[Minor][type_of(pos.piece_on(pop_lsb(&b)))];
+        {
+            Square s = pop_lsb(&b);
+            score += Threat[Minor][type_of(pos.piece_on(s))];
+            if (type_of(pos.piece_on(s)) != PAWN)
+                score += ThreatByRank * (int)relative_rank(Them, s);
+        }
 
         b = (pos.pieces(Them, QUEEN) | weak) & ei.attackedBy[Us][ROOK];
         while (b)
-            score += Threat[Rook ][type_of(pos.piece_on(pop_lsb(&b)))];
+        {
+            Square s = pop_lsb(&b);
+            score += Threat[Rook][type_of(pos.piece_on(s))];
+            if (type_of(pos.piece_on(s)) != PAWN)
+                score += ThreatByRank * (int)relative_rank(Them, s);
+        }
 
         score += Hanging * popcount(weak & ~ei.attackedBy[Them][ALL_PIECES]);