Solving geometric constraint systems. I. A global propagation approach

Abstract

We describe a geometric constraint solving method/system that takes the declarative description of geometric diagrams or engineering drawings as input and outputs a sequence of steps to construct the diagram with ruler and compass if it succeeds. We extend the local propagation to a global one. Like the local propagation, the global propagation tries to determine the position of a geometric object from the set of geometric objects whose positions are already known. However, our global propagation uses not only the constraints involving this object but also implicit information derived from other constraints. The algorithm can be used to build intelligent CAD and interactive computer graphic systems.