ring@cg-atla.UUCP (Steve Ring) (12/18/87)
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 o. o @ | @ where | / */ @ Ps @ angles a | / /* Ps @ *** @ are given x | / Pm * / @ * | * @ as i | / o P2 @ * | * @ s | /(ang1) /(ang2) P0 *----o----* P2 ---------------*-------- Pm x axis The Interpress commands are, where P2=(x2,y2), P1=(x1,y1), P0=(x0,y0) x2 y2 MOVETO X1 Y2 X0 Y0 <Shape> CONICTO 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 I have many pages of formular calculations, Is there another a simplier was 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