Here is the code we adapted in class from the array-based pong implementation we did last week:
// program: pongobject.tic // description: simple struct-based pong-like game as a base for breakout // script: js // // You will need 2 foreground tiles created to use this program: // #257: your paddle segment sprite (which we'll duplicate) // #258: your ball sprite // ////////////////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////////////////// // // getRandomDirection() is a function to query the random number // generator to produce one of -1 or 1, used to set one of the ball // direction attributes (xdir, ydir). // function getRandomDirection() { ////////////////////////////////////////////////////////////////////////// // // The random number generator is not returning a whole number, so // we need a routine to strip the decimal places from it. // var min = Math.ceil(0); var max = Math.floor(1); var value = Math.floor (Math.random () * (max - min + 1)) + min; ////////////////////////////////////////////////////////////////////////// // // Should the generated value be 0, adjust it to -1, to match our // desired output of -1 or 1. // if (value == 0) { value = -1; } return (value); } ////////////////////////////////////////////////////////////////////////////// // // Giving english names to button IDs (easier to remember and read) // var left = 2; var right = 3; ////////////////////////////////////////////////////////////////////////////// // // General variables // var index = 0; var screenwidth = 240; var screenheight = 136; ////////////////////////////////////////////////////////////////////////////// // // paddle is a structure that will be packed with tile and // coordinate data for our player // var paddle = { tile: 257, wide: 2, x: 0, y: screenheight - 8 - 5, }; paddle.x = (screenwidth / 2) - ((8 * paddle.wide) / 2); ////////////////////////////////////////////////////////////////////////////// // // ball is a structure that will be packed with tile and // coordinate data for the missile // var ball = { tile: 258, wide: 1, x: 0, y: (screenheight - (screenheight / 3)), xdir: getRandomDirection(), ydir: getRandomDirection(), }; ball.x = (screenwidth / 2) - ((8 * ball.wide) / 2); function TIC() { cls(0); ////////////////////////////////////////////////////////////////////////// // // Check to see if the left arrow is being pressed // if (btn (left) == true) { ////////////////////////////////////////////////////////////////////// // // Adjust the x position of the paddle by decrementing it // paddle.x = paddle.x - 1; ////////////////////////////////////////////////////////////////////// // // Bounds check: see if that recent movement moved us off the // left side of the screen (x-axis position of 0). If we have, // reset the x coordinate of the paddle to 0. // if (paddle.x < 0) { paddle.x = 0; } } ////////////////////////////////////////////////////////////////////////// // // Check to see if the left right arrow is being pressed // if (btn (right) == true) { ////////////////////////////////////////////////////////////////////// // // Adjust the x position of the paddle by incrementing it // paddle.x = paddle.x + 1; ////////////////////////////////////////////////////////////////////// // // Bounds check: see if that recent movement moved us off the // right side of the screen (x-axis position of 240). If we have, // reset the x coordinate of the paddle to a position such that it // is bumping against the right side of the screen. // // This requires some calculations, since tiles are 8 pixels wide, // and we are doubling up our display of the paddle tiles (so 16); // that means, since coordinates of sprites are referenced from a // top-left perspective, we take the screen width (240) and then // subtract our total sprite width (16 for a double wide) // if (paddle.x > (screenwidth - (8 * paddle.wide))) { paddle.x = screenwidth - (8 * paddle.wide); } } ////////////////////////////////////////////////////////////////////////// // // Display the paddle, compensating for width of desired sprite // for (index = 0; index < paddle.wide; index++) { spr (paddle.tile, paddle.x+(index*8), paddle.y, 0); } ////////////////////////////////////////////////////////////////////////// // // Move ball along its current path (determined by xdir // and ydir current states) // ball.x = ball.x + (1 * ball.xdir); ball.y = ball.y + (1 * ball.ydir); ////////////////////////////////////////////////////////////////////////// // // Bounds checking for the ball: left side of screen: reflect // it and send it in the opposite direction. // if (ball.x < 0) { ball.xdir = 1; } ////////////////////////////////////////////////////////////////////////// // // Bounds checking for the ball: right side of screen: reflect // it and send it in the opposite direction. // if (ball.x + (8 * ball.wide) > screenwidth) { ball.xdir = -1; } ////////////////////////////////////////////////////////////////////////// // // Bounds checking for the ball: top of screen: reflect // it and send it in the opposite direction. // if (ball.y < 0) { ball.ydir = 1; } ////////////////////////////////////////////////////////////////////////// // // Loss for player: paddle misses ball and ball leaves the // bottom of the screen. Reset ball to starting position. // if (ball.y + (8 * ball.wide) > screenheight) { ////////////////////////////////////////////////////////////////////// // // Same code as above: reset ball to its starting point // ball.x = (screenwidth / 2) - ((8 * ball.wide) / 2); ball.y = screenheight - (screenheight / 3); ////////////////////////////////////////////////////////////////////// // // Same code for initializing xdir and ydir above: obtain // a random choice of -1 or 1 // ball.xdir = getRandomDirection(); ball.ydir = getRandomDirection(); } ////////////////////////////////////////////////////////////////////////// // // Collision detection: is the top of the paddle coming into // contact with the ball? Check and react accordingly (reflect // the ball away). // // This requires the use of a compound condition in our if(), // as we need to check both x and y axis within the range of // the paddle to determine if we have a hit. // if ((ball.y+(8*ball.wide) >= paddle.y) && // ball on y-plane (ball.x >= (paddle.x - (8*ball.wide))) && // left side (ball.x <= (paddle.x + (8*paddle.wide))) && // right side (ball.y <= (paddle.y + 8))) // bottom { ////////////////////////////////////////////////////////////////////// // // Place ball above the paddle // ball.y = paddle.y - 8; ////////////////////////////////////////////////////////////////////// // // Reflect the ball away // ball.ydir = -1; } ////////////////////////////////////////////////////////////////////////// // // Display the ball sprite // spr (ball.tile, ball.x, ball.y, 0); }