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Re: Beginner Question: PlotS rasterization info? [message #27800 is a reply to message #27794]

Wed, 07 November 2001 11:03

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

sandy <sehgal@oasis.rad.upenn.edu> writes:

> When PlotS or Plot rasterizes straight lines between endpoints/vertices,
> what's the best way to get the coordinates of all the points
> interpolated? Surely this information is stored somewhere. Can I get
> these coordinates without actually plotting anything to the screen? I
> tried a Bresenham algorithm, but it doesn't return exactly the same
> interpolated points as PlotS--there appears to be some sort of roundoff
> difference. Any help would be appreciated, since currently I'm
> resorting to the roundabout and no doubt inefficient method of plotting
> to a pixmap, TVRD-ing, and then WHERE-ing the screen-dumped array....

Greetings Ted (Sandy?)--

If it's really important to you to have exactly the same pixels on the
screen and in your array, then probably your pixmap/WHERE approach is
the most reliable.

If you already have the Bresenham algorithm coded, then what reason is
there to use PLOTS? In other words, why not plot the pixel values you
determined from the Bresenham, and then you can be sure you know them
exactly?

Craig

--
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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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[Message index]

		Re: Beginner Question: PlotS rasterization info? By: David Fanning on Wed, 07 November 2001 15:18
		Re: Beginner Question: PlotS rasterization info? By: sandy on Wed, 07 November 2001 14:20
		Re: Beginner Question: PlotS rasterization info? By: Craig Markwardt on Wed, 07 November 2001 11:03
		Re: Beginner Question: PlotS rasterization info? By: David Fanning on Wed, 07 November 2001 09:10

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