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I did some more digging and it looks like this changed with the
transforms. curve4 is now being called instead of arc_to, which uses
beziers.
On Dec 9, 2007 10:11 AM, Charlie Moad <cw...@gm...> wrote:
> I found a great doc I am linking. The 4 spline method we are using
> has an error tolerance of 2.7*10^-4, which I am pretty sure is coming
> into play here. If we move to an 8 spline approach, it would reduce
> the error a few orders of magnitude.
>
> http://www.tinaja.com/glib/ellipse4.pdf
>
> - Charlie
>
>
>
> On Dec 8, 2007 9:09 AM, John Hunter <jd...@gm...> wrote:
> > On Dec 7, 2007 6:02 PM, James Evans <jre...@ea...> wrote:
> >
> > > There appears to be an issue with the agg backend with how it is drawing
> > > ellipses (or maybe it is how matplotlib uses agg), but the attached script
> > > shows how a point, which should be coincident with the center circle, but it
> > > is not. The second plot shows the same data, but using a custom (and much
> > > slower) algorithm for drawing the ellipses, where the point is properly
> > > coincident.
> >
> > Thanks for the test case James -- I will try and sort this out ASAP.
> > Michael, do you see the same on the transforms branch? The branch is
> > on a newer version of agg so if not, perhaps it is a simple matter of
> > upgrading agg on the trunk. I'm travelling currently bt will be back
> > omorrow and ill look at this ASAP.
> >
> > JDH
> >
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>

I found a great doc I am linking. The 4 spline method we are using
has an error tolerance of 2.7*10^-4, which I am pretty sure is coming
into play here. If we move to an 8 spline approach, it would reduce
the error a few orders of magnitude.
http://www.tinaja.com/glib/ellipse4.pdf
- Charlie
On Dec 8, 2007 9:09 AM, John Hunter <jd...@gm...> wrote:
> On Dec 7, 2007 6:02 PM, James Evans <jre...@ea...> wrote:
>
> > There appears to be an issue with the agg backend with how it is drawing
> > ellipses (or maybe it is how matplotlib uses agg), but the attached script
> > shows how a point, which should be coincident with the center circle, but it
> > is not. The second plot shows the same data, but using a custom (and much
> > slower) algorithm for drawing the ellipses, where the point is properly
> > coincident.
>
> Thanks for the test case James -- I will try and sort this out ASAP.
> Michael, do you see the same on the transforms branch? The branch is
> on a newer version of agg so if not, perhaps it is a simple matter of
> upgrading agg on the trunk. I'm travelling currently bt will be back
> omorrow and ill look at this ASAP.
>
> JDH
>
> -------------------------------------------------------------------------
> SF.Net email is sponsored by:
> Check out the new SourceForge.net Marketplace.
> It's the best place to buy or sell services for
> just about anything Open Source.
> http://sourceforge.net/services/buy/index.php
> _______________________________________________
> Matplotlib-devel mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
>