ring@cg-atla.UUCP (Steve Ring X5092) (12/17/87)
I need some help in formulating the equations for calculating the shape
parameter in the CONICTO command. Specifically, I am trying to draw an
elliptical arc between 2 angles, given
1) the origin of the elliptical arc, (some x, y point)
2) the major and minor axes lengths, (some length in say inches)
3) the two angles (say between 30-60 degrees).
P1
o ******\ P1
@|@ y | P0*. /
@ | @ where | / */
@ Ps @ angles a | / /* Ps
@ *** @ are given x | / Pm * /
@ * | * @ as i | / * P2
@ * | * @ s | /(ang1) /(ang2)
P0 *----o----* P2 ---------------*--------
Pm x axis
The * is the elliptical arc, the /\ are tangents draw to the arc @ P0, and P2
that meet at P1, Pm is the midpoint of P0-P2, Ps is the point on the curve at
which the curve intersects Pm-P1. The shape parameter is then the ratio of
the distances Pm-Ps and Pm-P1
Is there another way to do this in Interpress???
--
Steve Ring, Compugraphic Corp. Wilmington, Mass. 01887 (617)658-5600 X5092
"Remember - wherever you go...there you are"
...!{decvax,ima,ism780c,ulowell,laidbak,cgeuro,cg-f}!cg-atla!ring