uni_informatik_projekt/src/break_out/model/Ball.java

package break_out.model;

import break_out.Constants;

/**
 * This class contains the information about the balls characteristics and behavior
 *
 * @author iSchumacher
 * @author modified by Gruppe 175: Moritz Henseleit, Ruben Meyer
 */
public class Ball implements IBall {

	/**
	 * The balls position on the playground
	 */
	private Position position;

	/**
	 * The balls direction
	 */
	private Vector2D direction;

	/**
	 * The constructor of a ball
	 * The balls position and direction are initialized here.
	 */
	public Ball() {
		this.position = new Position(0, 0);
		this.direction = new Vector2D(Constants.BALL_SPEED, Constants.BALL_SPEED);
		this.direction.rescale();

		// start at bottom-center
		this.position.setX((Constants.SCREEN_WIDTH - Constants.BALL_DIAMETER) / 2.0);
		this.position.setY(Constants.SCREEN_HEIGHT - Constants.BALL_DIAMETER - Constants.PADDLE_HEIGHT);
	}

	/**
	 * The getter for the balls position
	 *
	 * @return position The balls current position
	 */
	public Position getPosition() {
		return this.position;
	}

	/**
	 * The getter for the balls direction
	 *
	 * @return direction The balls current direction
	 */
	public Vector2D getDirection() {
		return this.direction;
	}

	/**
	 * updates ball position
	 */
	public void updatePosition() {
		// sets X position
		this.position.setX(this.position.getX() + this.direction.getDx());

		// sets Y position
		this.position.setY(this.position.getY() + this.direction.getDy());
	}

	/**
	 * Ball reacts to contact with the borders
	 */
	public void reactOnBorder() {
		// reacts on left border
		if (this.position.getX() <= 0) {
			this.position.setX(0);
			this.direction.setDx(-(this.direction.getDx()));
		}

		// reacts on right border (-Diameter because of hitbox)
		if (this.position.getX() >= Constants.SCREEN_WIDTH - Constants.BALL_DIAMETER) {
			this.position.setX(Constants.SCREEN_WIDTH - Constants.BALL_DIAMETER);
			this.direction.setDx(-(this.direction.getDx()));
		}

		// reacts on top border
		if (this.position.getY() <= 0) {
			this.position.setY(0);
			this.direction.setDy(-(this.direction.getDy()));
		}

		// reacts on bottom border (+Diameter because of hitbox)
		if (this.position.getY() >= Constants.SCREEN_HEIGHT - Constants.BALL_DIAMETER) {
			this.position.setY(Constants.SCREEN_HEIGHT - Constants.BALL_DIAMETER);
			this.direction.setDy(-(this.direction.getDy()));
		}
	}

	/**
	 * tests whether the ball touches the paddle's hit box.
	 * @param paddle paddle which will be tested
	 * @return true when ball hits the paddle
	 */
	public boolean hitsPaddle(Paddle paddle) {
		// paddles position
		Position posPaddle = paddle.getPosition();

		// balls position
		Position posBall = this.getPosition();

		// test balls y position against paddles y values
		// paddles y values can be interpreted as a closed interval therefore if balls y position is in the interval, its true
		boolean testPaddleY = (
				posPaddle.getY() <= posBall.getY() && posBall.getY() <= posPaddle.getY()+paddle.getHeight() ||
				posPaddle.getY() <= posBall.getY()+Constants.BALL_DIAMETER && posBall.getY()+Constants.BALL_DIAMETER <= posPaddle.getY()+paddle.getHeight()
		);

		// test balls x position against paddles x values
		// paddles x values can be interpreted as a closed interval therefore if balls x position is in the interval, its true
		boolean testPaddleX = (
				posPaddle.getX() <= posBall.getX() && posBall.getX() <= posPaddle.getX()+paddle.getWidth() ||
				posPaddle.getX() <= posBall.getX()+Constants.BALL_DIAMETER && posBall.getX()+Constants.BALL_DIAMETER <= posPaddle.getX()+paddle.getWidth()
		);

		// if balls y position is in paddles y values, verify x position
		if(testPaddleY) {
			// DEBUG OUTPUT
			//System.out.println("ball is in y area of paddle: "+String.format("x, y, w, h: %s, %s, %s, %s", posPaddle.getX(), posPaddle.getY(), paddle.getWidth(), paddle.getHeight()));

			// if ball is in paddles hit box
			if(testPaddleX) {
				// DEBUG OUTPUT
				//System.out.println("ball hits paddle: "+String.format("x, y, w, h: %s, %s, %s, %s", posPaddle.getX(), posPaddle.getY(), paddle.getWidth(), paddle.getHeight()));

				return true;
			}

		}

		// default output, ball doesn't hit paddle
		return false;
	}

	/**
	 * Ball got hit by Paddle paddle
	 * @param paddle hitbox mechanism of paddle
	 * @todo implementation
	 */
	public void reflectOnPaddle(Paddle p) {
		// get the Position of the middle of the paddle
		Position newOffset = new Position(
			p.getPosition().getX() + p.getWidth() / 2.0,//the middle of the x coordinates
			p.getPosition().getY() + p.getHeight() / 2.0);//the middle of the y coordinates
		//deciding if the paddle is at the top or bottom to adjust if its +or- y direction
		if (p.getPosition().getY() == 0) { 		    
			newOffset.setY(newOffset.getY() - Constants.REFLECTION_OFFSET);// paddle at the top with negative direction
		} else {		   
			newOffset.setY(newOffset.getY() + Constants.REFLECTION_OFFSET); // the paddle at the bottom with positive direction
		}
		
		// calculating the center of the ball by dividing by zero
		Position ballCenter = new Position(
			position.getX() + Constants.BALL_DIAMETER/2.0, //the middle of the x coordinates
			position.getY() + Constants.BALL_DIAMETER/2.0); //the middle of the y coordinates
		
		// The direction is set to the middle of the offset point and the ball
		direction = new Vector2D(newOffset, ballCenter);
		// rescaling to adjust the balls speed
		direction.rescale();
	    }

}