Tuesday, September 15, 2015

A small Tetris-like Morphic component in Pharo

As part of my exploration of Pharo, I wanted to create a small basic/naive/incomplete implementation of a Tetris-like game as a Morphic component. Here's an example of the current state of the code:

Implementation

The (still incomplete) implementation is very simple. It uses a matrix to represent the game state. When we want to paint the current game state, we examine the matrix and paint a small rectangle for each of the occupied positions.

drawOn: canvas
   "Draws the current game state"
   |rows columns currentValue rectangle currentColor cellWidth cellHeight|

   rows := gameState size x.
   columns := gameState size y.
   
   super drawOn: canvas.
   
   cellWidth :=   ((self width) / columns) asFloat truncated.
   cellHeight :=   ((self height) / rows) asFloat truncated.
   1 to: rows do: [ :row |
      1 to: columns do: [ :column|
         currentValue := gameState at: row at: column .
         currentValue ~= 0 ifTrue: [ 
            currentColor := (colors at: currentValue).
            rectangle := Rectangle left: (self bounds left) + ((column - 1)*cellWidth) 
                                   right: (self bounds left) + ((column - 1)*cellWidth) + cellWidth
                                   top: (self bounds top) + ((row - 1)*cellHeight )
                                   bottom: (self bounds top) + ((row - 1)*cellHeight ) + cellHeight.
            canvas frameAndFillRectangle: rectangle
                  fillColor:  currentColor
                  borderWidth:  1
                  borderColor: (Color white).
             ]
          ]
       ].

Each Tetrimino is also represented as a small matrix.

Here's the definition for the 'J' and 'S' tetriminos:


   kind = #J ifTrue: [ 
      resultTetrimino := 
         Tetrimino 
            create: gameMatrix 
            tetriminoMatrix: 
               (Matrix rows: 2 
                  columns: 3 
                  contents: { 1. 1. 1.
                              0. 0. 1. })  
            colorIndex: 5.
      ].

...

   kind = #S ifTrue: [ 
      resultTetrimino := 
         Tetrimino 
            create: gameMatrix 
            tetriminoMatrix: 
               (Matrix rows: 2 
                  columns: 3 
                  contents: { 0. 1. 1.
                              1. 1. 0. })  
            colorIndex: 3.
      ].

The implementation is still incomplete, I hope that future posts will show more progress.

The source code can be found here: http://www.github.com/ldfallas/TryTrix .

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