PURPOSE: To efficiently and exactly generate an ellipse by determining the delta X and the delta Y normalized for each of the major axis and minor axis of a desired ellipse by using a unit circle supplying a parameter angle.
CONSTITUTION: By increasing the first angle value θ for a unit circle 30 by an incremental angle value Δθ, a cumulative angle value is obtained, the cosine difference ΔX and the sine difference ΔY for a first cumulative angle value and a second cumulative angle value are obtained, and the values ΔX and ΔY for an ellipse are obtained by multiplying the coside difference value ΔX and the sine difference value ΔY and the major axis conversion factor a and the minor axis conversion factor b showing the major axis and the minor axis of a preliminarily selected ellipse 32. At this time, a parameter angle θ is not the angle #1p between an x-axis and the line drawn from an origin up to the point (x, y) and the two angles are related by an expression tanθ=(b/a)tanθP. Thus, the ellipse and an elliptic arc can be efficiently and exactly generated.
| JP2002144642 | IMAGING SYSTEM |
| JPH0275086 | PICTURE PROCESSOR |
| JPH01219886 | SHADING PATTERN GENERATING DEVICE AND DISPLAY DEVICE |
POORU JIEI SHIYOOTO
TOOMASU EI UEINGAATONAA
| JPS5311332A | 1978-02-01 |