Homework 28 — due Friday December 7 by end of class

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• Implement five functions for module support.py. The module supports the initializing and updating of a 15 tile game. The functions are:

• inbounds()

• slide_left()

• slide_right()

• slide_up()

• slide_down()

Descriptions of the functions are available at the end of the module functions section.

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Discussion

• The image needs to be divided into 4 x 4 equal-sized tiles with the lower-righthand corner tile missing.

• Because the image width and height are not necessarily multples of 4 in length, the right and bottoms might need to be pared.

• The sixteen tiles will be labeled using their row and columns indices:

canonical_ordering = [

      ( 0, 0 ), ( 1, 0 ), ( 2, 0 ), ( 3, 0 ),

      ( 0, 1 ), ( 1, 1 ), ( 2, 1 ), ( 3, 1 ),

      ( 0, 2 ), ( 1, 2 ), ( 2, 2 ), ( 3, 2 ),

      ( 0, 3 ), ( 1, 3 ), ( 2, 3 ), ( 3, 3 ) ]

• A random ordering of the grid locations is alse needed.

ordering = canonical_ordering[ : ]

random.shuffle( ordering )

random_ordering = ordering

• One data structure will be maintained

• BOARD — the current image of the 15 puzzle

• For every board tile there is a left, right, top, and bottom line surrounding it.

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Module functions

Function initialize_globals( img )

• Initializes the global variables to appropriate values based on image img

global LINE_WIDTH, GRID_COLOR, TILE_DIMENSIONS, BOARD, BLACK_TILE, BLACK_TILE_SPOT

LINE_WIDTH = 4

GRID_COLOR = 'SteelBlue'

TILE_DIMENSIONS = ( img.width // 4, img.height // 4 )

BLACK_TILE = Image.new( 'RGB', TILE_DIMENSIONS, 'Black' )

BLACK_TILE_SPOT = ( 3, 3 )

BOARD = Image.new( 'RGB', ( img.width + 5*LINE_WIDTH, img.height + 5*LINE_WIDTH ), GRID_COLOR )

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Function crop( img )

• Returns a cropped RGB-based version of image img. The cropping has width four times the width of a tile and has height four times the height of a tile. A cropped image is necessary for the game in order to have an image composed of equally-sized tiles.

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Function translate_spot_into_board_coordinate( g_spot )

• Returns the board coordinate of the upper-left-hand corner of the tile at grid location g_spot. The coordinate can be determined by taking into account the number of tiles and lines to the left of g_spot.

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Function translate_spot_into_image_coordinate( g_spot )

• Returns the image img coordinate of the upper-left-hand corner of the tile at grid location g_spot. The coordinate can be determined by taking into account the number of tiles to the left of g_spot.

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Function overlay( tile, g_spot )

• Copies tile onto the board at grid location g_spot; that is,

• Gets the translation of g_spot into a board coordinate.

• Pastes tile onto the board at the appropiate coordinate.

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Function get_image_tile( img, g_spot )

• Returns the tile in img at grid location g_spot.

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Function initialize_board( img )

• Overlays the tiles of img onto the board. Every grid spot on the board is overlaid with the corresponding tile from img except for the tile at board grid location (3, 3), which is overlaid with black tile.

• The black tile spot is set to (3, 3).

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Function scramble_board( img )

• Overlays the tiles of img to random grid spots on the board except for the tile at spot (3, 3). That spot is overlaid with the black tile.

• The black tile spot is set to (3, 3).

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Function setup( img )

• Performs four actions:

• Initializes the global variables.

• Gets a cropped version of img.

• Initializes the board using the cropped image.

• Returns the cropped image.

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Function get_board_tile( g_spot )

• Returns the tile in the board at grid location g_spot.

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Function inbounds( spot )

• Determines whether spot is a valid grid location for a 15 puzzle. That is, whether the row and column values of spot are both legal — at least 0 and at most 3.

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Function slide_black_tile_left()

• Determines the grid spot to the left of the black tile. If the leftward spot is inbounds, simulates sliding the black tile to that spot. The sliding actions taken are:

• Overlay the leftward board tile onto the board spot of the black tile.

• Overlay the black tile on the now freed-up board spot.

• Update the location of the black tile.

If instead the leftward spot is out of bounds, no action is taken.

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Function slide_black_tile_right()

• Determines the grid spot to the right of the black tile. If the rightward spot is inbounds, simulates sliding the black tile to that spot. Otherwise, no action is taken.

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Function slide_black_tile_down()

• Determines the grid spot below the black tile. If the downward spot is inbounds, simulates sliding the black tile to that spot. Otherwise, no action is taken.

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Function slide_black_tile_up()

• Determines the grid spot above the black tile. If the upward spot is inbounds, simulates sliding the black tile to that spot. Otherwise, no action is taken.

 

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© 2019 Jim Cohoon

Resources from previous semesters are available.