HELP LINE_INTERSECTION                              David Young
                                                    February 1997

LIB * LINE_INTERSECTION computes the intersection point of two lines on
a plane. The lines are specified using the coordinates of two points on
each.

line_intersection(a1, a2,  b1, b2,  c1, c2,  d1, d2) -> (s1, s2)
        The points (a1, a2) and (b1, b2) lie on one line; the points
        (c1, c2) and (d1, d2) lie on the other. The point (s1, s2) will
        lie on the intersection. (Here a1 and a2 are the Cartesian
        coordinates of the point a.) If the lines are parallel s1 and s2
        will be <false>.

        The intersection point s might lie on the line segments a to b
        and c to d, but it might not. Examples:


                 a                       c|
                |                         |
                |                         +s
        c       |s      d                 |
        --------+--------                 | \ a
                |                         |  \
                |b                        |   \
                                         d|    \ b



                        \a
                         \
                          \b

               c--------d   +s


--- $popvision/help/line_intersection
--- Copyright University of Sussex 1997. All rights reserved.