Inferring Graphical Constraints with Rockit

Solange Karsenty, James A. Landay, and Chris Weikart

HCI '92 Proceedings, York, UK, September 1992, pp. 137-153.
(also published as DEC Paris Research Laboratory Research Report
17, March 1992)

Rockit is a system that identifies the possible graphical
constraints between objects in a two-dimensional scene and allows
the user to choose and apply the desired constraints quickly and
easily.  Rockit looks for intersections between the position of a
designated object and the gravity fields of other objects to
determine the possible constraints. These candidate constraints
are passed to a rule system that encodes some simple knowledge
about how graphical objects normally interact and can thus be
constrained to one another.  The rules are used to determine the
most likely constraints to be applied between the designated
object and the other objects in the scene. As the user
manipulates the object, the object will gravitate towards the
most likely constraint scenario. The inferred constraints are
indicated by the creation of graphical and sonic feedback
objects.  Rockit makes it easy to try other likely scenarios by
simply pressing a key, causing the system to cycle through the
other possibilities.