Bi-directional display of circular arcs
US4371933A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 6, 1980 |
| Grant date | Feb 1, 1983 |
| Priority date | — |
| Expiry date | Oct 6, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G5/20
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An improved method and apparatus are disclosed for generating circular arcs of any arc length greater than zero up to and including a full circle of 360 degrees. The method and apparatus can locate nonsymmetrical closest points for noninteger radius and arc center values. The method and apparatus is capable of generating the incremental move commands for drawing an arc either in the clockwise or counter clockwise direction which is a distinct advantage when used to drive a pen type electromechanical plotter. By dividing the generation of a 360 degree arc into eight octants, only two of the original eight directions need to be considered as candidate directions toward the next integer display matrix value to be displayed. The method and apparatus employ a novel initialization which provides a simple stopping test for any circular arc of arbitrary length and direction. Only simple addition and sign testing is used to display the circular arc.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.