improving check generation

1 files changed, 17 insertions, 10 deletions

diff --git a/src/bot.cpp b/src/bot.cpp
index a1b4fb2..f1f1fd6 100644
--- a/src/bot.cpp
+++ b/src/bot.cpp
@@ -17,7 +17,7 @@ const int KNIGHT_VALUE = 320;
 const int BISHOP_VALUE = 330;
 const int ROOK_VALUE = 500;
 const int QUEEN_VALUE = 900;
-const int CHECK = 10;
+const int CHECK_BIAS = 10;
 const int MATE = 10000;
 
 const int PAWN_TABLE[64] = {
@@ -218,21 +218,21 @@ float minimax(int depth, Game *b, float alpha, float beta) {
 }
 int PSTIndex(int square, bool white) { return white ? square : (56 ^ square); }
 
-float EvaluateBoardForWhite(Game *b, int depth) {
+float EvaluateBoardForWhite(Game *g, int depth) {
   float score = 0;
 
-  if (b->state == WHITE_WON) {
+  if (g->state == WHITE_WON) {
     return MATE + depth;
   }
-  if (b->state == BLACK_WON) {
+  if (g->state == BLACK_WON) {
     return -MATE - depth;
   }
-  if (b->state == STALEMATE || b->state == DRAW) {
+  if (g->state == STALEMATE || g->state == DRAW) {
     return 0;
   }
 
   for (int i = 0; i < 64; i++) {
-    Piece piece = b->pieces[i];
+    Piece piece = g->pieces[i];
     if (piece.type == NONEPIECE)
       continue;
 
@@ -271,11 +271,18 @@ float EvaluateBoardForWhite(Game *b, int depth) {
     else
       score -= value;
   }
-  if (IsPieceTypeAttacked(b, KING, true)) {
-    score -= CHECK; // white king attacked
+
+  Position WhiteKingPosition = FindKing(g, g->turn);
+  bool IsWhiteIncheck = IsSquareAttacked(g, WhiteKingPosition, !g->turn);
+
+  Position BlackKingPosition = FindKing(g, g->turn);
+  bool IsBlackInCheck = IsSquareAttacked(g, BlackKingPosition, !g->turn);
+
+  if (IsWhiteIncheck) {
+    score -= CHECK_BIAS; // white king attacked
   }
-  if (IsPieceTypeAttacked(b, KING, false)) {
-    score += CHECK; // black king attacked
+  if (IsBlackInCheck) {
+    score += CHECK_BIAS; // black king attacked
   }
   return score;
 }