public static boolean isInBox(final float x,final float y,final float radius){
  return Math.abs(x) <= Math.abs(radius) && Math.abs(y) <= Math.abs(radius);
}

public static boolean isInBox ( final float x , final float y , final float radius ) { return Math . abs ( x ) <= Math . abs ( radius ) && Math . abs ( y ) <= Math . abs ( radius ) ; }
see if the x , y coordinate is inside the box . it is assumed that the " grid " being tested is located at 0 , 0 and its dimensions are 2 * radius .
