MapGrid coordinates
Step 1: slice the map into columns(red)
Calculate how far away from the edge the point is(green). The green
point is less than the hexside width, so the hexpart x is (2 *
column - 1).
The blue point is more than the hexside width, so
the hexpart x is 2* column
Step 2: slice the map into rows.
If it is a side hexside from before, the hexpart y is ( 2 * row +1 ).
If it is a center or bottom hexside,
add 1/4 hexagon height to adjust for the down shift and the hexpart y
is ( 2 * row ).
the rectangles are called:
center hexpart
lower hexpart
upper left hexpart
lower left hexpart
The hexpart coordinate will be the blue dot.
The hexagon coordinate will be the closest hexagon center from the mouse
cursor at the red dot.
