Breakout03 Collision

    //Major method which moves the ball, causes constraints on the ball's movements(within the screen) and bounces the ball
        private void playTurn() {
            double vx = rgen.nextDouble(1.0, 3.0);
            if(rgen.nextBoolean(.5)) vx=-vx;
            double vy = Y_VELOCITY;
            while (true) {
                if(numBricksLeft == 0)
                    break;
                if(ball.getY() > APPLICATION_HEIGHT)
                    break;
                ball.move(vx,vy);
                pause(ANIMATION_PAUSE);

                vy = reflectOffColliders(vy);
                vx = reflectOffSideWalls(vx);
                vy = reflectOffTopWall(vy);
            }
        }

        /**
         * Change the y velocity if it hits a collider
         * @param vy
         * @return
         */
        private double reflectOffColliders(double vy) {
            GObject collider = getCollidingObject();
            if (collider == paddle) {
                bounceClip.play();
                vy = -Math.abs(vy);
            }
            else if (collider != null) {
                remove(collider);
                vy *= -1;
            }
            return vy;
        }

        /**
         * Get top screen bound and reverse velocity
         * @param vy
         * @return
         */
        private double reflectOffTopWall(double vy) {
            if (ball.getY() < 0) {
                vy *= -1;
            }
            return vy;
        }

        /**
         * Get side bounds and reverse x velocity
         * @param vx
         * @return
         */
        private double reflectOffSideWalls(double vx) {
            if (ball.getX() < 0 || ball.getX() > APPLICATION_WIDTH - ball.getWidth()) {
                vx *= -1;
            }
            return vx;
        }