added functions which predict the outcome of a piece drop
This commit is contained in:
Christian Kroll
parent
072964dc6d
commit
326585e5ac
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@ -119,6 +119,26 @@ void tetris_playfield_reset(tetris_playfield_t *pPl)
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}
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int8_t tetris_playfield_getPieceStartPos(tetris_piece_t *pPiece)
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{
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// set vertical start position (first piece row with matter at pos. 1)
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uint16_t nPieceMap = tetris_piece_getBitmap(pPiece);
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uint16_t nElementMask = 0xF000;
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int8_t nRow = -3;
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while ((nPieceMap & nElementMask) == 0)
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{
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++nRow;
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nElementMask >>= 4;
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}
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if (nRow < 0)
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{
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++nRow;
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}
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return nRow;
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}
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/* Function: tetris_playfield_insertPiece
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* Description: inserts a new piece
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* Argument pPl: playfield to perform action on
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@ -146,18 +166,7 @@ void tetris_playfield_insertPiece(tetris_playfield_t *pPl,
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pPl->nColumn = (pPl->nWidth - 2) / 2;
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// set vertical start position (first piece row with matter at pos. 1)
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uint16_t nPieceMap = tetris_piece_getBitmap(pPl->pPiece);
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uint16_t nElementMask = 0xF000;
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pPl->nRow = -3;
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while ((nPieceMap & nElementMask) == 0)
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{
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++pPl->nRow;
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nElementMask >>= 4;
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}
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if (pPl->nRow < 0)
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{
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++pPl->nRow;
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}
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pPl->nRow = tetris_playfield_getPieceStartPos(pPl->pPiece);
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// did we already collide with something?
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if (tetris_playfield_collision(pPl, pPl->nColumn, pPl->nRow) == 1)
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@ -593,3 +602,142 @@ uint16_t tetris_playfield_getDumpRow(tetris_playfield_t *pPl,
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return pPl->dump[nRow];
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}
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/* Function: tetris_playfield_predictDeepestRow
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* Description: returns the deepest possible row of a given piece
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* Argument pPl: the playfield on which we want to test a piece
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* Argument pPiece: the piece which should be tested
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* Argument nColumn: the column where the piece should be dropped
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* Return value: the row of the piece (playfield compliant coordinates)
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*/
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int8_t tetris_playfield_predictDeepestRow(tetris_playfield_t *pPl,
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tetris_piece_t *pPiece,
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int8_t nColumn)
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{
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int8_t nRow = tetris_playfield_getPieceStartPos(pPiece);
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tetris_piece_t *pActualPiece = pPl->pPiece;
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pPl->pPiece = pPiece;
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// is it actually possible to use this piece?
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if (tetris_playfield_collision(pPl, (pPl->nWidth - 2) / 2, nRow) ||
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(tetris_playfield_collision(pPl, nColumn, nRow)))
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{
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return -4;
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}
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// determine deepest row
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while ((nRow < pPl->nHeight) &&
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(!tetris_playfield_collision(pPl, nColumn, nRow + 1)))
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{
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++nRow;
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}
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// restore real piece
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pPl->pPiece = pActualPiece;
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return nRow;
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}
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/* Function: tetris_playfield_predictCompleteLines
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* Description: predicts the number of complete lines for a piece at
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* a given column
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* Argument pPl: the playfield on which we want to test a piece
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* Argument pPiece: the piece which should be tested
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* Argument nColumn: the column where the piece should be dropped
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* Return value: amount of complete lines
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*/
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int8_t tetris_playfield_predictCompleteLines(tetris_playfield_t *pPl,
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tetris_piece_t *pPiece,
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int8_t nColumn)
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{
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int8_t nCompleteRows = 0;
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// bit mask of a full row
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uint16_t nFullRow = 0xFFFF >> (16 - pPl->nWidth);
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int8_t nRow = tetris_playfield_predictDeepestRow(pPl, pPiece, nColumn);
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if (nRow > -4)
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{
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// determine sane start and stop values for the dump's index
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int8_t nStartRow =
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((nRow + 3) >= pPl->nHeight) ? pPl->nHeight - 1 : nRow + 3;
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int8_t nStopRow = (nRow < 0) ? 0 : nRow;
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uint16_t nPiece = tetris_piece_getBitmap(pPiece);
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for (int8_t i = nStartRow; i >= nStopRow; --i)
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{
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int8_t y = i - nRow;
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// clear all bits of the piece we are not interested in and
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// align the rest to LSB
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uint16_t nPieceMap = (nPiece & (0x000F << (y << 2))) >> (y << 2);
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// shift the remaining content to the current column
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if (nColumn >= 0)
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{
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nPieceMap <<= nColumn;
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}
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else
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{
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nPieceMap >>= -nColumn;
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}
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// embed piece in dump map
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uint16_t nDumpMap = pPl->dump[i] | nPieceMap;
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// is current row a full row?
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if ((nFullRow & nDumpMap) == nFullRow)
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{
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++nCompleteRows;
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}
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}
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}
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return nCompleteRows;
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}
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/* Function: tetris_playfield_predictDumpRow
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* Description: predicts the appearance of a playfield row for a piece
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* at a given column
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* Argument pPl: the playfield on which we want to test a piece
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* Argument pPiece: the piece which should be tested
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* Argument nColumn: the column where the piece should be dropped
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* Argument nRow: the row of interest
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* Return value: amount of complete lines
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*/
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uint16_t tetris_playfield_predictDumpRow(tetris_playfield_t *pPl,
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tetris_piece_t *pPiece,
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int8_t nColumn,
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int8_t nRow)
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{
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int8_t nPieceRow = tetris_playfield_predictDeepestRow(pPl, pPiece, nColumn);
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uint16_t nPieceMap = 0;
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if (nPieceRow > -4)
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{
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// determine sane start and stop values for the piece's indices
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int8_t nStartRow = ((nPieceRow + 3) < pPl->nHeight) ?
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(nPieceRow + 3) : pPl->nHeight - 1;
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uint16_t nPiece = tetris_piece_getBitmap(pPiece);
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if ((nRow <= nStartRow) && (nRow >= nPieceRow))
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{
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int8_t y = nRow - nPieceRow;
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// clear all bits of the piece we are not interested in and
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// align the rest to LSB
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nPieceMap = (nPiece & (0x000F << (y << 2))) >> (y << 2);
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// shift the remaining content to the current column
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if (nColumn >= 0)
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{
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nPieceMap <<= nColumn;
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}
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else
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{
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nPieceMap >>= -nColumn;
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}
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}
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}
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return pPl->dump[nRow] | nPieceMap;
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}
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@ -209,5 +209,43 @@ uint16_t tetris_playfield_getDumpRow(tetris_playfield_t *pPl,
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int8_t nRow);
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#endif /*TETRIS_PLAYFIELD_H_*/
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/* Function: tetris_playfield_predictDeepestRow
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* Description: returns the deepest possible row of a given piece
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* Argument pPl: the playfield on which we want to test a piece
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* Argument pPiece: the piece which should be tested
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* Argument nColumn: the column where the piece should be dropped
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* Return value: the row of the piece (playfield compliant coordinates)
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*/
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int8_t tetris_playfield_predictDeepestRow(tetris_playfield_t *pPl,
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tetris_piece_t *pPiece,
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int8_t nColumn);
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/* Function: tetris_playfield_predictCompleteLines
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* Description: predicts the number of complete lines for a piece at
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* a given column
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* Argument pPl: the playfield on which we want to test a piece
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* Argument pPiece: the piece which should be tested
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* Argument nColumn: the column where the piece should be dropped
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* Return value: amount of complete lines
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*/
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int8_t tetris_playfield_predictCompleteLines(tetris_playfield_t *pPl,
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tetris_piece_t *pPiece,
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int8_t nColumn);
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/* Function: tetris_playfield_predictDumpRow
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* Description: predicts the appearance of a playfield row for a piece
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* at a given column
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* Argument pPl: the playfield on which we want to test a piece
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* Argument pPiece: the piece which should be tested
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* Argument nColumn: the column where the piece should be dropped
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* Argument nRow: the row of interest
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* Return value: amount of complete lines
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*/
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uint16_t tetris_playfield_predictDumpRow(tetris_playfield_t *pPl,
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tetris_piece_t *pPiece,
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int8_t nColumn,
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int8_t nRow);
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#endif /*TETRIS_PLAYFIELD_H_*/
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