Just as well throw mine into the mix, too:
Global vl_intersect_x, vl_intersect_y
;
; Determines whether two lines intersect, or not. If the lines do intersect, the
; point of intersection is returned in the global variables vl_intersect_x and vl_intersect_y.
;
; Params:
; x1,y1 - Start coords of first line.
; dx1,dy1 - Delta coords of first line.
; x2,y2 - Start coords of second line.
; dx2,dy2 - Delta coords of second line.
;
; Returns:
; True if the lines intersect, false otherwise.
;
Function vl__lines_intersect_xy(x1#, y1#, dx1#, dy1#, x2#, y2#, dx2#, dy2#)
u_b# = dy2 * dx1 - dx2 * dy1
If (u_b <> 0)
ua_t# = (dx2 * (y1 - y2)) - (dy2 * (x1 - x2))
ub_t# = (dx1 * (y1 - y2)) - (dy1 * (x1 - x2))
ua# = ua_t / u_b
ub# = ub_t / u_b
If (ua >= 0 And ua <= 1 And ub >= 0 And ub <= 1)
vl_intersect_x = x1 + (ua * dx1)
vl_intersect_y = y1 + (ua * dy1)
Return True
EndIf
EndIf
Return False
End Function
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