Short of bespoke algorithms, the best results so far have
been achieved with con?¬?gurable hybrid algorithms: the user can choose certain kinds
of objects and relationships to be routed one way, for example, as a Manhattan tree,
and others to be routed by a more generic least-line-length approach.
Connection Boundaries for Role Lines Whatever the route, the last leg of a
role line will point toward a certain point on an object. Normally this should be the
center of the object, since that is clearest for the eye to read, as well as being
esthetically balanced. It also means that the modeler need do no extra work to keep
separate the intersections of roles from various sources. As he moves connected
objects around, their role lines automatically follow, pointing at the center all the time.
In cases where the visual center of an object is not at the center of the total area of its
elements, it should be possible to de?¬?ne a speci?¬?c target point that role lines head to.
For instance, in a Use Case Actor symbol you may want roles to connect either to the
stick ?¬?gure, and move the target point up there, or to the text label below, and move the
target point down to the center of the label.
???Version 1.0??? tools may not offer true center-based role directing, since it requires
somewhat more work in calculating the intersection of the role line and the symbol.
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