The offset to the left mentioned above can be seen on the left in the role at
A from D. The roles at C from A and E appear to be at the wrong end of the line: the
midpoint of the text element is rather far from the role end in the symbol. A better
solution overall is on the right, where the text element is square. The text remains
symmetrically aligned over the line, and close to the correct role end. This approach
will work even in tools that rotate the text boundary. The downside is that the role line
will always cross the text element, unlike AB and ED with the previous symbol.
Role Line Routing Animportant part of the tool support for a graphical modeling
language is how role lines connect to objects. A role line must follow a certain route,
with the last leg pointing to a certain point in an object symbol, and stopping where it
intersects the symbol.
The route of a role line is generally made up of straight lines between freely
positioned points. Most commonly, the line will simply head directly from the
relationship to the object with no intermediate points. This is the optimal case, as the
eye can follow it most simply to read models: the line is the shortest distance between
the objects it connects, and thus lies on the natural path of the eye between those
objects.
Those with a background in chip design will tend to look for a perpendicular or
Manhattan routing of lines: all segments of the line are either horizontal or vertical,
with no diagonal segments.
Pages:
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721