The PADL-1.0/2 system for defining and displaying solid objects

Abstract

PADL (Part and Assembly Description Language) is a language for defining solid objects via constructive solid geometry, i.e. as (regularized) set-theoretical compositions of primitive solid “building blocks”. The current processor for Version 1.0 of the language accepts PADL statements either in batch or in keyboard-interactive mode and produces line drawings of objects on CRT's and plotting devices. A variety of drawing styles is available: dimensioned orthographics, perspectives, section views, interference drawings, etc. Novel characteristics of the PADL-1.0/2 system include 1) general combinational operators that may be applied to any part defined in PADL, 2) correct handling of “pathologies” that occur when (for example) two objects have partially coincident boundaries, 3) maintenance of consistent multiple representations of the same object, and 4) automatic posting on drawings of dimensions to reflect user-defined geometric relations between features of objects. This paper provides an overview of both the language and the current processor's capabilities and organization. Detailed discussions of the underlying mathematics, algorithms, and implementation are presented elsewhere.