intxy

Finds the first point along line a where an intersection

Returns the location of the first intersection of a and b. If the intersection occurs along a segment (as opposed to at a vertex), then the decimal value of ia (or ib) defines the distance between the intersection and preceeding vertex as a portion of the overall length of the segment containing the intersection. For example, an intersection occurring halfway between the 2nd and 3rd vertices of line "a" would return ia=2.5. Likewise, an intersection 1/4 the way between vertices 1 and 2 would return ia=1.25.