public static boolean isInRadius(float x,float y,float radius){
  Vector2f point=new Vector2f(x,y);
  return Math.abs(point.length()) <= radius;
}

public static boolean isInRadius ( float x , float y , float radius ) { Vector2f point = new Vector2f ( x , y ) ; return Math . abs ( point . length ( ) ) <= radius ; }
see if the x , y coordinate is in the radius of the circle . it is assumed that the " grid " being tested is located at 0 , 0 and its dimensions are 2 * radius .
