Re: [AGG] Curve smoothing/fitting

[Maxim S. <mc...@an...>]

Sorry for the delay,

I suppose the problem is in the conceptual difference between your 
interpolations. You have a chart y=f(x) and then smooth it with a spline 
(the points). Then you want to draw it with agg::conv_bspline, right? But it 
works differently. It's not y=f(x), it is:
x=fx(n)
y=fy(n)
Where n is the number of the point. It's how a 2D spline works.

The suggestion is to use only agg::bspline. You just store your calculated 
points in the agg::path_storage and draw them through the agg::conv_stroke.

McSeem

"Gus Grubba" <gu...@gr...> wrote in message 
news:B6E...@gr......
> Hi all,
>
> Sorry for posting this again but I did not see this in the archives
> so I'm assuming it didn't make it (even though I did receive my own
> post back)...
>
> I have a data set that is loaded and the user should be able to tweak
> the points. The problem I'm having is that the curve smoothing on the
> data plot does not match the results of the spline code. If I use
> agg::bspline for the interpolation, I see the same problem. In the
> this screen grab (http://www.grubba.com/agg.png), I've plotted the
> data using both agg::conv_bspline and data poked directly to memory
> out of the spline (both AGG and my plot are using the same data set).
> In this application, there is no "correct" way to handle the data.
>
> Whichever way works fine. I just need consistency. The solution is to
> either find a way for me to have the same data AGG is interpolating
> or a way for AGG to use my interpolations. My math is not good enough
> to understand all of this.
>
> TIA
>
> gus
>
>
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