x0: in, required
The x location of the one end of the first line segment.
y0: in, required
The y location of the one end of the first line segment.
x1: in, required
The x location of the other end of the first line segment.
y1: in, required
The y location of the other end of the first line segment.
x2: in, required
The x location of the one end of the second line segment.
y2: in, required
The y location of the one end of the second line segment.
x3: in, required
The x location of the other end of the second line segment.
y3: in, required
The y location of the other end of the second line segment.