project11 - template

11/Square/Main.jack

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+// This file is part of www.nand2tetris.org
+// and the book "The Elements of Computing Systems"
+// by Nisan and Schocken, MIT Press.
+// File name: projects/11/Square/Main.jack
+
+/** Initializes a new Square game and starts running it. */
+class Main {
+    function void main() {
+        var SquareGame game;
+        let game = SquareGame.new();
+        do game.run();
+        do game.dispose();
+        return;
+    }
+}

11/Square/Square.jack

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+// This file is part of www.nand2tetris.org
+// and the book "The Elements of Computing Systems"
+// by Nisan and Schocken, MIT Press.
+// File name: projects/11/Square/Square.jack
+
+/** Implements a graphical square.
+    The square has top-left x and y coordinates, and a size. */
+class Square {
+
+   field int x, y; // screen location of the top-left corner of this square
+   field int size; // length of this square, in pixels
+
+   /** Constructs and draws a new square with a given location and size. */
+   constructor Square new(int ax, int ay, int asize) {
+      let x = ax;
+      let y = ay;
+      let size = asize;
+      do draw();
+      return this;
+   }
+
+   /** Disposes this square. */
+   method void dispose() {
+      do Memory.deAlloc(this);
+      return;
+   }
+
+   /** Draws this square in its current (x,y) location */
+   method void draw() {
+      // Draws the square using the color black
+      do Screen.setColor(true);
+      do Screen.drawRectangle(x, y, x + size, y + size);
+      return;
+   }
+
+   /** Erases this square. */
+   method void erase() {
+      // Draws the square using the color white (background color)
+      do Screen.setColor(false);
+      do Screen.drawRectangle(x, y, x + size, y + size);
+      return;
+   }
+
+    /** Increments the square size by 2 pixels (if possible). */
+   method void incSize() {
+      if (((y + size) < 254) & ((x + size) < 510)) {
+         do erase();
+         let size = size + 2;
+         do draw();
+      }
+      return;
+   }
+
+   /** Decrements the square size by 2 pixels (if possible). */
+   method void decSize() {
+      if (size > 2) {
+         do erase();
+         let size = size - 2;
+         do draw();
+      }
+      return;
+   }
+
+   /** Moves this square up by 2 pixels (if possible). */
+   method void moveUp() {
+      if (y > 1) {
+         // Erases the bottom two rows of this square in its current location
+         do Screen.setColor(false);
+         do Screen.drawRectangle(x, (y + size) - 1, x + size, y + size);
+         let y = y - 2;
+         // Draws the top two rows of this square in its new location
+         do Screen.setColor(true);
+         do Screen.drawRectangle(x, y, x + size, y + 1);
+      }
+      return;
+   }
+
+   /** Moves the square down by 2 pixels (if possible). */
+   method void moveDown() {
+      if ((y + size) < 254) {
+         do Screen.setColor(false);
+         do Screen.drawRectangle(x, y, x + size, y + 1);
+         let y = y + 2;
+         do Screen.setColor(true);
+         do Screen.drawRectangle(x, (y + size) - 1, x + size, y + size);
+      }
+      return;
+   }
+
+   /** Moves the square left by 2 pixels (if possible). */
+   method void moveLeft() {
+      if (x > 1) {
+         do Screen.setColor(false);
+         do Screen.drawRectangle((x + size) - 1, y, x + size, y + size);
+         let x = x - 2;
+         do Screen.setColor(true);
+         do Screen.drawRectangle(x, y, x + 1, y + size);
+      }
+      return;
+   }
+
+   /** Moves the square right by 2 pixels (if possible). */
+   method void moveRight() {
+      if ((x + size) < 510) {
+         do Screen.setColor(false);
+         do Screen.drawRectangle(x, y, x + 1, y + size);
+         let x = x + 2;
+         do Screen.setColor(true);
+         do Screen.drawRectangle((x + size) - 1, y, x + size, y + size);
+      }
+      return;
+   }
+}

11/Square/SquareGame.jack

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+// This file is part of www.nand2tetris.org
+// and the book "The Elements of Computing Systems"
+// by Nisan and Schocken, MIT Press.
+// File name: projects/11/Square/SquareGame.jack
+/**
+ * Implements the Square game.
+ * This simple game allows the user to move a black square around
+ * the screen, and change the square's size during the movement.
+ * When the game starts, a square of 30 by 30 pixels is shown at the
+ * top-left corner of the screen. The user controls the square as follows.
+ * The 4 arrow keys are used to move the square up, down, left, and right.
+ * The 'z' and 'x' keys are used, respectively, to decrement and increment
+ * the square's size. The 'q' key is used to quit the game.
+ */
+class SquareGame {
+   field Square square; // the square of this game
+   field int direction; // the square's current direction: 
+                        // 0=none, 1=up, 2=down, 3=left, 4=right
+
+   /** Constructs a new square game. */
+   constructor SquareGame new() {
+      // The initial square is located in (0,0), has size 30, and is not moving.
+      let square = Square.new(0, 0, 30);
+      let direction = 0;
+      return this;
+   }
+
+   /** Disposes this game. */
+   method void dispose() {
+      do square.dispose();
+      do Memory.deAlloc(this);
+      return;
+   }
+
+   /** Moves the square in the current direction. */
+   method void moveSquare() {
+      if (direction = 1) { do square.moveUp(); }
+      if (direction = 2) { do square.moveDown(); }
+      if (direction = 3) { do square.moveLeft(); }
+      if (direction = 4) { do square.moveRight(); }
+      do Sys.wait(5);  // delays the next movement
+      return;
+   }
+
+   /** Runs the game: handles the user's inputs and moves the square accordingly */
+   method void run() {
+      var char key;  // the key currently pressed by the user
+      var boolean exit;
+      let exit = false;
+      
+      while (~exit) {
+         // waits for a key to be pressed
+         while (key = 0) {
+            let key = Keyboard.keyPressed();
+            do moveSquare();
+         }
+         if (key = 81)  { let exit = true; }     // q key
+         if (key = 90)  { do square.decSize(); } // z key
+         if (key = 88)  { do square.incSize(); } // x key
+         if (key = 131) { let direction = 1; }   // up arrow
+         if (key = 133) { let direction = 2; }   // down arrow
+         if (key = 130) { let direction = 3; }   // left arrow
+         if (key = 132) { let direction = 4; }   // right arrow
+
+         // waits for the key to be released
+         while (~(key = 0)) {
+            let key = Keyboard.keyPressed();
+            do moveSquare();
+         }
+     } // while
+     return;
+   }
+}
+
+
+