// The following evaluation function was adapted from Pascal code submitted by:
// Pierre Dellacherie (France). (E-mail : [email protected])
//
// This amazing one-piece algorithm completes an average of roughly 600 000
// rows, and often attains 2 000 000 or 2 500 000 rows. However, the algorithm
// sometimes completes as few as 15 000 rows. I am fairly certain that this
// is NOT due to statistically abnormal patterns in the falling piece sequence.
//
// Pierre Dellacherie corresponded with me via e-mail to help me with the
// conversion of his Pascal code to C++.
//
// WARNING:
// If there is a single board and piece combination with the highest
// 'rating' value, it is the best combination. However, among
// board and piece combinations with EQUAL 'rating' values,
// the highest 'priority' value wins.
//
// So, the complete rating is: { rating, priority }.
void PrivateStrategyEvaluate
(
STBoard board,
STPiece piece,
ref double rating,
ref int priority
)
{
rating = 0.0;
priority = 0;
if (false == piece.IsValid())
{
return;
}
int boardWidth = 0;
int boardHeight = 0;
boardWidth = board.GetWidth();
boardHeight = board.GetHeight();
int pieceMinX = 0;
int pieceMinY = 0;
int pieceMaxX = 0;
int pieceMaxY = 0;
piece.GetTranslatedBoundingRectangle
(ref pieceMinX, ref pieceMinY, ref pieceMaxX, ref pieceMaxY);
// Landing Height (vertical midpoint)
double landingHeight = 0.0;
landingHeight = 0.5 * (double)(pieceMinY + pieceMaxY);
int completedRows = 0;
completedRows = board.GetTotalCompletedRows();
int erodedPieceCellsMetric = 0;
if (completedRows > 0)
{
// Count piece cells eroded by completed rows before doing collapse on pile.
int pieceCellsEliminated = 0;
pieceCellsEliminated = board.CountPieceCellsEliminated(piece);
// Now it's okay to collapse completed rows
board.CollapseAnyCompletedRows();
// Weight eroded cells by completed rows
erodedPieceCellsMetric = (completedRows * pieceCellsEliminated);
}
// Note that this evaluation of pile height is AFTER collapsing
// any completed rows.
int pileHeight = 0;
pileHeight = board.GetPileMaxHeight();
// Each empty row (above pile height) has two (2) "transitions"
// (We could call ref_Board.GetTransitionCountForRow( y ) for
// these unoccupied rows, but this is an optimization.)
int boardRowTransitions = 0;
boardRowTransitions = 2 * (boardHeight - pileHeight);
// Only go up to the pile height, and later we'll account for the
// remaining rows transitions (2 per empty row).
int y = 0;
for (y = 1; y <= pileHeight; y++)
{
boardRowTransitions += (board.GetTransitionCountForRow(y));
}
int boardColumnTransitions = 0;
int boardBuriedHoles = 0;
int boardWells = 0;
int x = 0;
for (x = 1; x <= boardWidth; x++)
{
boardColumnTransitions += board.GetTransitionCountForColumn(x);
boardBuriedHoles += board.GetBuriedHolesForColumn(x);
boardWells += board.GetAllWellsForColumn(x);
}
// Final Rating
rating = (0.0);
rating += ((-1.0) * (landingHeight));
rating += ((1.0) * ((double)(erodedPieceCellsMetric)));
rating += ((-1.0) * ((double)(boardRowTransitions)));
rating += ((-1.0) * ((double)(boardColumnTransitions)));
rating += ((-4.0) * ((double)(boardBuriedHoles)));
rating += ((-1.0) * ((double)(boardWells)));
// EXPLANATION:
// [1] Punish landing height
// [2] Reward eroded piece cells
// [3] Punish row transitions
// [4] Punish column transitions
// [5] Punish buried holes (cellars)
// [6] Punish wells
#if DEBUGGING_PRINT_STATEMENTS
STEngine.GetConsole().AddLine
(
" D:" + (21.0 - landingHeight)
+ " R:" + erodedPieceCellsMetric
+ " RC:" + (-boardRowTransitions)
+ " CC:" + (-boardColumnTransitions)
+ " H:" + (-4 * boardBuriedHoles)
+ " W:" + (-boardWells)
);
#endif
// PRIORITY:
// Priority is further differentiation between possible moves.
// We further rate moves accoding to the following:
// * Reward deviation from center of board
// * Reward pieces to the left of center of the board
// * Punish rotation
// Priority is less important than the rating, but among equal
// ratings we select the option with the greatest priority.
// In principle we could simply factor priority in to the rating,
// as long as the priority was less significant than the smallest
// variations in rating, but for large board widths (>100), the
// risk of loss of precision in the lowest bits of the rating
// is too much to tolerate. So, this priority is stored in a
// separate variable.
int absoluteDistanceX = 0;
absoluteDistanceX = (piece.GetX() - board.GetPieceSpawnX());
if (absoluteDistanceX < 0)
{
absoluteDistanceX = (-(absoluteDistanceX));
}
priority = 0;
priority += (100 * absoluteDistanceX);
if (piece.GetX() < board.GetPieceSpawnX())
{
priority += 10;
}
priority -= (piece.GetOrientation( ) - 1);
}