104 lines
2.9 KiB
Plaintext
104 lines
2.9 KiB
Plaintext
// This file is part of www.nand2tetris.org
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// and the book "The Elements of Computing Systems"
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// by Nisan and Schocken, MIT Press.
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// File name: projects/11/Pong/Bat.jack
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/**
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* A graphical Pong bat.
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* Displayed as a filled horizontal rectangle that has
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* a screen location, a width and a height.
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* Has methods for drawing, erasing, moving left and right,
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* and changing its width (to make the hitting action more challenging).
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* This class should have been called "paddle", following the
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* standard Pong terminology. But, unaware of this terminology,
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* we called it "bat", and then decided to stick to it.
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*/
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class Bat {
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field int x, y; // the bat's screen location
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field int width, height; // the bat's width and height
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field int direction; // direction of the bat's movement (1 = left, 2 = right)
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/** Constructs a new bat with the given location and width. */
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constructor Bat new(int Ax, int Ay, int Awidth, int Aheight) {
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let x = Ax;
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let y = Ay;
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let width = Awidth;
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let height = Aheight;
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let direction = 2;
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do show();
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return this;
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}
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/** Deallocates the object's memory. */
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method void dispose() {
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do Memory.deAlloc(this);
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return;
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}
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/** Shows the bat. */
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method void show() {
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do Screen.setColor(true);
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do draw();
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return;
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}
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/** Hides the bat. */
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method void hide() {
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do Screen.setColor(false);
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do draw();
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return;
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}
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/** Draws the bat. */
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method void draw() {
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do Screen.drawRectangle(x, y, x + width, y + height);
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return;
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}
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/** Sets the bat's direction (0=stop, 1=left, 2=right). */
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method void setDirection(int Adirection) {
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let direction = Adirection;
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return;
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}
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/** Returns the bat's left edge. */
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method int getLeft() {
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return x;
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}
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/** Returns the bat's right edge. */
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method int getRight() {
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return x + width;
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}
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/** Sets the bat's width. */
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method void setWidth(int Awidth) {
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do hide();
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let width = Awidth;
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do show();
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return;
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}
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/** Moves the bat one step in the bat's direction. */
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method void move() {
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if (direction = 1) {
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let x = x - 4;
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if (x < 0) { let x = 0; }
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do Screen.setColor(false);
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do Screen.drawRectangle((x + width) + 1, y, (x + width) + 4, y + height);
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do Screen.setColor(true);
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do Screen.drawRectangle(x, y, x + 3, y + height);
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}
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else {
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let x = x + 4;
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if ((x + width) > 511) { let x = 511 - width; }
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do Screen.setColor(false);
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do Screen.drawRectangle(x - 4, y, x - 1, y + height);
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do Screen.setColor(true);
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do Screen.drawRectangle((x + width) - 3, y, x + width, y + height);
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}
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return;
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}
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}
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