I'm using Processing to develop a very simple board game for starters.  I currently have the grid mapped out as an 8x8 tiled grid, but I am unsure how to go about making each tile become a true container for the game piece. 

      i.e. If the piece is on the line between two spaces, the piece will either pick one container or the other, not simply                   dropping on the line between the two. 

Thanks!