public void update(float delta){        
        Vector2D position = circleShape.getPosition();
        if((position.x -radius/2)<0){ circleShape.setXPosition(radius/2); velocity.thisBounceNormal(new Vector2D(1,0));}
        if((position.x +radius/2)>GamePanel.WIDTH){ circleShape.setXPosition(GamePanel.WIDTH-radius/2);velocity.thisBounceNormal(new Vector2D(-1,0));}
        if((position.y -radius/2)<0){circleShape.setYPosition(radius/2);velocity.thisBounceNormal(new Vector2D(0,1));}
        if((position.y +radius/2)>GamePanel.HEIGHT){ circleShape.setYPosition(GamePanel.HEIGHT-radius/2);velocity.thisBounceNormal(new Vector2D(0,-1));}
        Vector2D c = new Vector2D(position.x - Mouse.x, position.y -Mouse.y);
        if (c.length() < 100){
            c.thisNormalize();
            c.thisScale(1);
            velocity.thisAdd(c);
        }
        
        if (velocity.length() > 20)
        {
            velocity.thisNormalize();
            velocity.thisScale(10);
        }
        position.thisAdd(velocity.scale(delta)); 
    }