Bi-directional display of circular arcs

Details Bi-directional display of circular arcs Bi-directional display of circular arcs

1980-10-06

1983-02-01

Wise, Edward J.

Boots, shoes, and leggings

364720, 364522, G06F 1531, G06F 3153

Patent

active

043719333

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.

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J. E. Bresenham, A Linear Algorithm for Incremental Digital Display of Circular Arcs Communications of the ACM 20, 2 (Feb. 1977), 100-106.
Z. Kulpa, On the Properties of Discrete Circles, Rings, and Disks, Computer Graphics and Image Processing, vol. 10, No. 4, (Aug. 1979) pp. 348-365.
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