// if no collision happened, move the blockers each in turn,
            // checking if they leave the window and, if so, bouncing them back
            if (proceed) {
                blocker1.move();
                if (blocker1.getX()<0) {
                    blocker1.rebound(0);
                }
                if (blocker1.getX()>WIN_SIZE-blocker1.getW()) {
                    blocker1.rebound(WIN_SIZE-blocker1.getW());
                }
                blocker2.move();
                if (blocker2.getX()<0) {
                    blocker2.rebound(0);
                }
                if (blocker2.getX()>WIN_SIZE-blocker2.getW()) {
                    blocker2.rebound(WIN_SIZE-blocker2.getW());
                }
                blocker3.move();
                if (blocker3.getX()<0) {
                    blocker3.rebound(0);
                }
                if (blocker3.getX()>WIN_SIZE-blocker3.getW()) {
                    blocker3.rebound(WIN_SIZE-blocker3.getW());
                }

                // after the blockers move, check again to see if the player
                // has been hit
                if (marker.collides(blocker1.getX(), blocker1.getY(), blocker1.getW(),
                                blocker1.getH()) ||
                    marker.collides(blocker2.getX(), blocker2.getY(), blocker2.getW(),
                                blocker2.getH()) ||
                    marker.collides(blocker3.getX(), blocker3.getY(), blocker3.getW(),
                                blocker3.getH())) {
                    Random gen = new Random();
                    marker.setX(gen.nextInt(WIN_SIZE-marker.getD()));
                    marker.setY(WIN_SIZE+BUFFER_SIZE-marker.getD()-10);
                }
            }