Browse Prior Art Database

Area-Fill Boundaries Using Coded Vectors

IP.com Disclosure Number: IPCOM000099658D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 75K

Publishing Venue

IBM

Related People

Gay, AC: AUTHOR [+2]

Abstract

This disclosure describes an enhancement in graphical line drawing techniques previously published in the two references given below. The basic area-fill algorithm is described in (1). The enhancement of this algorithm uses a property of the invention described in [2].

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Area-Fill Boundaries Using Coded Vectors

       This disclosure describes an enhancement in graphical
line drawing techniques previously published in the two references
given below.  The basic area-fill algorithm is described in (1).  The
enhancement of this algorithm uses a property of the invention
described in [2].

      The scheme described in (2) shows how the set-up time and, in
some implementations, the line drawing performance, of arbitrary
length 'short' line can be improved, by precalculating the direction
steps taken by all possible lines up to some length limit (depending
on storage available).  The binary string representing axial/diagonal
direction steps (normalized to 1st octant) for the Bresenham
incremental line drawing algorithm, uses a binary 'O' to represent
'draw a pixel and step diagonally', and a binary '1' to represent
'draw a pixel and step axially'.

      The algorithm described in reference (1) performs area-filling
by drawing the outline of the area in a 1-bit/pixel map and then
scanning to find edges.  In the case of edge lines classed as
'X-major', i.e., runs of pixels generated along the scanning axis,
steps must be taken to ensure only pixel/run is drawing, for the
algorithm to function correctly.  This has been most efficiently
achieved using the alternative Bresenham Run Length incremental line
drawing algorithm which steps in the minor, rather than major axis,
thus effectively generating one pixel per run (minor axis step).  The
disadvantage being that the division during the setup of this
algorithm makes the line setup time even longer, although the pixel
drawing can be quicker.

      The concept of coded direction can be extended to improve the
setup...