HIRASP: A Hierarchical Interactive Rastergraphics System Based on Pattern Graphs and Pattern Expressions

Abstract

To exploit the full capabilities of raster graphics, two and three dimensional drawing primitives should play a preponderant role in the specification of a graphics standard. In addition there should be facilities for modeling and hierarchy. HIRASP presents an integrated language system fulfilling these requirements. The pattern is used as the basic drawing primitive. It consists of a colour function defined over an arbitrary OD to 3D domain. There are a number of basic pattern primitives. Arbitrarily complex patterns may be composed from pattern expressions. But once an expression is assigned to a pattern, the constituent structure loses its existence. Patterns define the static structure of HIRASP. On top of this a dynamic structure is built to allow for interactive modification. This dynamic structure can be represented as a directed graph, the so-called pattern graph. Patterns are the leaves of this graph. Each node carries a set of alterable orthogonal attributes, controlling domain and colour transformations, highlighting, visibility, detectability, level, and transparency, for the subgraphs descending from the node. The interpretation (traversal) of the graph results in a 2 1/2D mapping, akin to the Painters algorithm, or a full 3D mapping, on a graphics screen.