Grid cell direction UV and Plan sometimes inverted and not consistent

Hi,

I have some problems while attempting to create a triangular pattern for a facade.

My main question is WHY some of the resulting cells some times are all in the same direction so that offset and further divisions are equal for all cells while other times the cells UV or Plans appear to be inverted in only some of the cells.

I noticed this behavior as I need to correct for example the length of input lines or their position in Rhino, so why this happen and there is a way to prevent that? Thanks!
triangular pattern _on facade_828_2018.gh (24.1 KB)


tri pattern.3dm (212.1 KB)