PongEngine.cpp

00001 #include "PongEngine.h"
00002 
00003 PongEngine::PongEngine(){ _lives = 4; }    
00004 
00005 void PongEngine::init(int paddle_position, int paddle_height, int paddle_width, int ball_size, int speed){
00006     //printf("Pong Engine: Init\n");
00007     _ball.init(ball_size,speed);
00008     _paddle.init(paddle_position, paddle_height, paddle_width);
00009 }
00010 
00011 int PongEngine::update(UserInput input) {   
00012     //printf("Pong Engine: Update\n");
00013     check_goal();  // checking for a goal is a priority 
00014     _ball.update();
00015     _paddle.update(input);
00016     // important to update paddles and ball before checking collisions so can
00017     // correct for it before updating the display
00018     check_wall_collision();
00019     check_paddle_collision();
00020     
00021     return _lives;
00022 }
00023 
00024 void PongEngine::draw(N5110 &lcd) {
00025     //printf("Pong Engine: Draw\n");
00026     // draw the elements in the LCD buffer
00027     // pitch
00028     lcd.drawLine(0,0,WIDTH-1,0,1);  // top
00029     lcd.drawLine(WIDTH-1,0,WIDTH-1,HEIGHT-1,1);  // back wall
00030     lcd.drawLine(0,HEIGHT-1,WIDTH-1,HEIGHT-1,1); // bottom
00031     _ball.draw(lcd);
00032     _paddle.draw(lcd);
00033 }
00034 
00035 void PongEngine::check_wall_collision() {
00036     //printf("Pong Engine: Check Wall Collision\n");
00037     // read current ball attributes
00038     Position2D ball_pos = _ball.get_pos();
00039     Position2D ball_velocity = _ball.get_velocity();
00040     int size = _ball.get_size();
00041 
00042     // check if hit top wall
00043     if (ball_pos.y <= 1) {  //  1 due to 1 pixel boundary
00044         ball_pos.y = 1;  // bounce off ceiling without going off screen
00045         ball_velocity.y = -ball_velocity.y;  // flip velocity
00046     } else if (ball_pos.y + size >= (HEIGHT-1) ) {
00047         // hit bottom
00048         ball_pos.y = (HEIGHT-1) - size;  // stops ball going off screen
00049         ball_velocity.y = -ball_velocity.y;    // flip velcoity 
00050     } else if (ball_pos.x + size >= (WIDTH-1) ) {
00051         // hit right wall
00052         ball_pos.x = (WIDTH-1) - size;  // stops ball going off screen
00053         ball_velocity.x = -ball_velocity.x;    // flip velcoity 
00054     } 
00055 
00056     // update ball parameters
00057     _ball.set_velocity(ball_velocity);
00058     _ball.set_pos(ball_pos);
00059 }
00060 
00061 void PongEngine::check_paddle_collision() {
00062     //printf("Pong Engine: Check Paddle Collision\n");
00063     // read current ball and paddle attributes
00064     Position2D ball_pos = _ball.get_pos();
00065     Position2D ball_velocity = _ball.get_velocity();
00066     Position2D paddle_pos = _paddle.get_pos();  // paddle
00067 
00068     // see if ball has hit the paddle by checking for overlaps
00069     if (
00070         (ball_pos.y >= paddle_pos.y) && //top
00071         (ball_pos.y <= paddle_pos.y + _paddle.get_height() ) && //bottom
00072         (ball_pos.x >= paddle_pos.x) && //left
00073         (ball_pos.x <= paddle_pos.x + _paddle.get_width() )  //right
00074     ) {
00075         // if it has, fix position and reflect x velocity
00076         ball_pos.x = paddle_pos.x + _paddle.get_width();
00077         ball_velocity.x = -ball_velocity.x;
00078     }
00079 
00080     // write new attributes
00081     _ball.set_velocity(ball_velocity);
00082     _ball.set_pos(ball_pos);
00083 }
00084 
00085 void PongEngine::check_goal() {
00086     //printf("Pong Engine: Check Goal\n");
00087     Position2D ball_pos = _ball.get_pos();
00088     int size = _ball.get_size();
00089     int speed = abs(_ball.get_velocity().x);  // speed is magnitude of velocity
00090     // check if ball position has gone off the left
00091     if (ball_pos.x + size < 0) {
00092         // reset the ball
00093         _ball.init(size,speed);
00094         _lives--;  // lose a life
00095     }   
00096 }