From a000308104aab27c2dde9a306f1bc654b2db4806 Mon Sep 17 00:00:00 2001 From: Yuchen Pei Date: Wed, 29 Nov 2017 12:30:41 +0100 Subject: first commit --- projects/11/Pong/Ball.jack | 203 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 203 insertions(+) create mode 100644 projects/11/Pong/Ball.jack (limited to 'projects/11/Pong/Ball.jack') diff --git a/projects/11/Pong/Ball.jack b/projects/11/Pong/Ball.jack new file mode 100644 index 0000000..02e47f9 --- /dev/null +++ b/projects/11/Pong/Ball.jack @@ -0,0 +1,203 @@ +// 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/Pong/Ball.jack + +/** + * A graphical ball. Characterized by a screen location and distance of + * last destination. Has methods for drawing, erasing and moving on the screen. + * The ball is displayed as a filled, 6-by-6 pixles rectangle. + */ +class Ball { + + field int x, y; // the ball's screen location (in pixels) + field int lengthx, lengthy; // distance of last destination (in pixels) + + field int d, straightD, diagonalD; // used for straight line movement computation + field boolean invert, positivex, positivey; // (same) + + field int leftWall, rightWall, topWall, bottomWall; // wall locations + + field int wall; // last wall that the ball was bounced off of + + /** Constructs a new ball with the given initial location and wall locations. */ + constructor Ball new(int Ax, int Ay, + int AleftWall, int ArightWall, int AtopWall, int AbottomWall) { + let x = Ax; + let y = Ay; + let leftWall = AleftWall; + let rightWall = ArightWall - 6; // -6 for ball size + let topWall = AtopWall; + let bottomWall = AbottomWall - 6; // -6 for ball size + let wall = 0; + do show(); + return this; + } + + /** Deallocates the Ball's memory. */ + method void dispose() { + do Memory.deAlloc(this); + return; + } + + /** Shows the ball. */ + method void show() { + do Screen.setColor(true); + do draw(); + return; + } + + /** Hides the ball. */ + method void hide() { + do Screen.setColor(false); + do draw(); + return; + } + + /** Draws the ball. */ + method void draw() { + do Screen.drawRectangle(x, y, x + 5, y + 5); + return; + } + + /** Returns the ball's left edge. */ + method int getLeft() { + return x; + } + + /** Returns the ball's right edge. */ + method int getRight() { + return x + 5; + } + + /** Computes and sets the ball's destination. */ + method void setDestination(int destx, int desty) { + var int dx, dy, temp; + let lengthx = destx - x; + let lengthy = desty - y; + let dx = Math.abs(lengthx); + let dy = Math.abs(lengthy); + let invert = (dx < dy); + + if (invert) { + let temp = dx; // swap dx, dy + let dx = dy; + let dy = temp; + let positivex = (y < desty); + let positivey = (x < destx); + } + else { + let positivex = (x < destx); + let positivey = (y < desty); + } + + let d = (2 * dy) - dx; + let straightD = 2 * dy; + let diagonalD = 2 * (dy - dx); + + return; + } + + /** + * Moves the ball one unit towards its destination. + * If the ball has reached a wall, returns 0. + * Else, returns a value according to the wall: + * 1 (left wall), 2 (right wall), 3 (top wall), 4 (bottom wall). + */ + method int move() { + + do hide(); + + if (d < 0) { let d = d + straightD; } + else { + let d = d + diagonalD; + + if (positivey) { + if (invert) { let x = x + 4; } + else { let y = y + 4; } + } + else { + if (invert) { let x = x - 4; } + else { let y = y - 4; } + } + } + + if (positivex) { + if (invert) { let y = y + 4; } + else { let x = x + 4; } + } + else { + if (invert) { let y = y - 4; } + else { let x = x - 4; } + } + + if (~(x > leftWall)) { + let wall = 1; + let x = leftWall; + } + if (~(x < rightWall)) { + let wall = 2; + let x = rightWall; + } + if (~(y > topWall)) { + let wall = 3; + let y = topWall; + } + if (~(y < bottomWall)) { + let wall = 4; + let y = bottomWall; + } + + do show(); + + return wall; + } + + /** + * Bounces off the current wall: sets the new destination + * of the ball according to the ball's angle and the given + * bouncing direction (-1/0/1=left/center/right or up/center/down). + */ + method void bounce(int bouncingDirection) { + var int newx, newy, divLengthx, divLengthy, factor; + + // dividing by 10 first since results are too big + let divLengthx = lengthx / 10; + let divLengthy = lengthy / 10; + if (bouncingDirection = 0) { let factor = 10; } + else { + if (((~(lengthx < 0)) & (bouncingDirection = 1)) | ((lengthx < 0) & (bouncingDirection = (-1)))) { + let factor = 20; // bounce direction is in ball direction + } + else { let factor = 5; } // bounce direction is against ball direction + } + + if (wall = 1) { + let newx = 506; + let newy = (divLengthy * (-50)) / divLengthx; + let newy = y + (newy * factor); + } + else { + if (wall = 2) { + let newx = 0; + let newy = (divLengthy * 50) / divLengthx; + let newy = y + (newy * factor); + } + else { + if (wall = 3) { + let newy = 250; + let newx = (divLengthx * (-25)) / divLengthy; + let newx = x + (newx * factor); + } + else { // assumes wall = 4 + let newy = 0; + let newx = (divLengthx * 25) / divLengthy; + let newx = x + (newx * factor); + } + } + } + + do setDestination(newx, newy); + return; + } +} -- cgit v1.2.3