Refine scale factor of opposite colored bishops endgames.

Vizvezdenec · vondele · commit eb4a124b8859 · 2020-05-02T17:30:22.000+02:00
This patch makes it dependant on the count of passed pawns of the strong side instead of 22/64 in every case. passed STC https://tests.stockfishchess.org/tests/view/5ead60966ffeed51f6e32591 LLR: 2.96 (-2.94,2.94) {-0.50,1.50} Total: 50336 W: 9473 L: 9241 D: 31622 Ptnml(0-2): 570, 5371, 13098, 5515, 614 passed LTC https://tests.stockfishchess.org/tests/view/5ead6d3b6ffeed51f6e325b0 LLR: 2.94 (-2.94,2.94) {0.25,1.75} Total: 21952 W: 2810 L: 2603 D: 16539 Ptnml(0-2): 101, 1791, 7005, 1958, 121 closes #2658 bench 4247490
diff --git a/src/evaluate.cpp b/src/evaluate.cpp
@@ -768,7 +768,7 @@ namespace {
         {
             if (   pos.non_pawn_material(WHITE) == BishopValueMg
                 && pos.non_pawn_material(BLACK) == BishopValueMg)
-                sf = 22;
+                sf = 18 + 4 * popcount(pe->passed_pawns(strongSide));
             else
                 sf = 22 + 3 * pos.count<ALL_PIECES>(strongSide);
         }

Original file line number	Diff line number	Diff line change
`@@ -768,7 +768,7 @@ namespace {`
`768`	`768`	`{`
`769`	`769`	`if ( pos.non_pawn_material(WHITE) == BishopValueMg`
`770`	`770`	`&& pos.non_pawn_material(BLACK) == BishopValueMg)`
`771`		`- sf = 22;`
	`771`	`+ sf = 18 + 4 * popcount(pe->passed_pawns(strongSide));`
`772`	`772`	`else`
`773`	`773`	`sf = 22 + 3 * pos.count<ALL_PIECES>(strongSide);`
`774`	`774`	`}`