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8.18: Letting the Piece “Naturally” Fall

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  • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)

            # let the piece fall if it is time to fall
            if time.time() - lastFallTime > fallFreq:
                # see if the piece has landed
                if not isValidPosition(board, fallingPiece, adjY=1):
                    # falling piece has landed, set it on the board
                    addToBoard(board, fallingPiece)
                    score += removeCompleteLines(board)
                    level, fallFreq = calculateLevelAndFallFreq(score)
                    fallingPiece = None
                    # piece did not land, just move the piece down
                    fallingPiece['y'] += 1
                    lastFallTime = time.time()

    The rate that the piece is naturally moving down (that is, falling) is tracked by the lastFallTime variable. If enough time has elapsed since the falling piece last fell down one space, lines 4 [279] to 13 [288] will handle dropping the piece by one space.

    If the condition on line 4 [279] is True, then the piece has landed. The call to addToBoard() will make the piece part of the board data structure (so that future pieces can land on it), and the removeCompleteLines() call will handle erasing any complete lines on the board and pulling the boxes down. The removeCompleteLines() function also returns an integer value of how many lines were removed, so we add this number to the score.

    Because the score may have changed, we call the calculateLevelAndFallFreq() function to update the current level and frequency that the pieces fall. And finally, we set the fallingPiece variable to None to indicate that the next piece should become the new falling piece, and a random new piece should be generated for the new next piece. (That is done on lines 195 to 199 at the beginning of the game loop.)

    If the piece has not landed, we simply set its Y position down one space (on line 12 [287]) and reset lastFallTime to the current time (on line 13 [288]).

    8.18: Letting the Piece “Naturally” Fall is shared under a CC BY-NC-SA 3.0 license and was authored, remixed, and/or curated by LibreTexts.

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