The efficiency of line drawing algorithms underwrites the performance of ma
ny rendering and visualisation systems. Therefore to significantly improve
the process of line drawing, techniques have been developed to draw the lin
e not pixel by pixel but by using higher order primitives such as runs and
run length slices. In this paper we present a line drawing algorithm based
on runs of runs, which is the next step in this progression. We will also d
iscuss a number of special cases in the structure of runs and runs of runs
within the line that can be used to short circuit the drawing process. Thes
e special cases can be used to help counter a common criticism that run-bas
ed techniques are less applicable for very short lines. In fact we will arg
ue that the use of higher order primitives provides additional structural i
nformation that can be used to accelerate secondary processes within the gr
aphics system, such as within the raster memory management. (C) 2001 Elsevi
er Science Ltd. All rights reserved.