[cl-gd-devel] just to share

[arry]

never mind my post I figured myself whats wrong

The angles that the function "draw-arc" accepts are 
actually the angles that the line that draws the ellipse
forms with the x-axes, which is not the angle between
the radius of the ellipse and the x-axes. Hope that is  clear

bye

--- Edi Weitz <edi at agharta.de> wrote:

> On Tue, 22 Nov 2005 03:54:35 -0800 (PST), arry <frinkofox at yahoo.com> wrote:
> 
> > I just want to share a problem with cl-gd or maybe gd itself i don't
> > know...
> >
> > Has anybody tried to draw an ellipse which starts and ends at a
> > precise angle?  Well, I have and it turns out that the angles that i
> > have specified are not drawn exact , they are either bigger or
> > smaller and SOMETIMES theyy are correct!
> >
> > is this a problem with gd  or cl-gd?
> >
> > example
> > I draw an ellipse that passes through two points then I want this
> > ellipse to start from exactly one of the two point aand end at the
> > other one. I calculate the angles with tthe help of the function
> > (atan) or (asin) using the coordinates of the center of the ellipse
> > and the two given points...
> >
> > and the angles drawn don't match with the given points That's
> > funny!!! ridiculous!!!  There's always 1 or 2 maybe more degrees
> > discrapency between the angles drawn and the given points
> 
> I don't have time to investigate this at the moment but if in doubt
> I'd first try with a similar C program to see if the problems are in
> GD.  You also might want to check if any rounding errors occur within
> CL-GD.
> 
> Good luck,
> Edi.
> 



		
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