Each square on the cube surface is defined by a specific **INDEX **or specific SIDE and SQUARE number.
These values are connected together by simple mathematics:
side = index / 9
square = index % 9
We can refer to squares either absolutely, that means we know their index, side and/or square, or we can place them on something called WALKER.
WALKER is a packed structure, that contains information not only about the position of the WALKER but also about its direction. This is very useful, because we can move WALKER forward, backward, rotate it etc. without paying attention what it's actual absolute position is.
Anytime after, we can retrieve information about it's position by simple predefined macros:
index = _i(walker)
side = _side(walker)
square = _square(walker)
Of course, the WALKER will always stick to the cube's surface, so moves correctly over the edges.
Many functions take WALKER directly as argument. For example, if we want to draw on the square defined by WALKER position, we simply use DrawPoint(walker). We do not need to add any macros.
Oftentimes, we will construct WALKER from a known square index or known side and square:
walker = _w(4, 4) // Defined by side and square
walker = _w(25) // Defined by specific index numberIn these cases, WALKER will have it's default direction. You can use the debug function DrawTail() to display the orientation of the WALKER automatically.
Macro i(...), which retrieves the index from the WALKER, is very useful to look up the index into an array, that represents, for example, a playground area.