code: public void setGrid(int width, int height)
      {
          Check.superiorStrict(width, 0);
          Check.superiorStrict(height, 0);
          gridWidth = width;
          gridHeight = height;
      }
docs: Set the grid size.
  
  @param width The horizontal grid (strictly positive).
  @param height The vertical grid (strictly positive).
  @throws LionEngineException If grid is not strictly positive.