Introduction

In interactive applications, 2D drawings are built up by different interactive functions of the applications. Similarly, 3D figures can be created by the combination of volume primitives. These operations normally work on entity level, that means, by the addition of lines, arcs, texts, or by the duplication of information of the drawing.

However, in many situations the drawing or volume to be created is parenthesized, that means, controlled by a relatively small number of parameters and/or conditions.

The Geometry Macro Facility has been developed as a tool to create such drawings/volumes by defining a number of parameters in calls of geometry macros.

A geometry macro is written as a text in a format like a programming language.

The elements of the language are:

• the geometrical entities that can be created

• "program logic", like branching and loops

• basic arithmetics, logical and trigonometrical operations

Details about all these things can be found below.