# another yucky geometry question

Jim Hurley jhurley at infostations.com
Tue Sep 27 11:04:06 EDT 2005

```TJ,

P.S. Over night thoughts:

If one wanted to extend the drawing of an ellipse bounded  by radial
lines with origin at the vanishing point, the  function "drawEllipse"

The difficult part would be determining the values of a,b,tAng, xLoc
and yLoc such that the ellipse is property sized, angled and
positioned so that it lies tangent to the given radials.

Jim

on drawEllipse a,b,tAng,xLoc,yLoc

repeat with aa = 1 to 360 step 4 --4 is a compromise: min jaggies
in min time.
put r(aa,tAng,a,b,) into r
put round(xLoc+ r*cos(pi/180*aa)),round(yLoc+r*sin(pi/180*aa)) &
cr after tPoints
end repeat
set the points of grc "ellipse" to tPoints

end drawEllipse

function r angl,phi,a,b

put cos(pi/180*(angl+phi)) into c
put sin(pi/180*(angl+phi)) into s
return sqrt(1/(c*c/a/a + s*s/b/b))-- Ellipse at angle phi

end r

drawEllispe 100,40,30,300,400 will draw an ellipse with a = 100, b =
40, at an angle of 30 degree and with a loc of 300,400

```