Re: [Visualpython-users] Pixel-oriented plotting

[Bruce S. <Bru...@nc...>]

I've just posted a corrected version of pixelplot.py in the contributed 
section of vpython.org. I made an off-by-one error in "connecting the 
dots" in the curves that are used with the production version of 
VPython. The effect was to blend/blur adjacent colors rather than make 
them distinct as intended.

Bruce Sherwood
> -----------------------
> A colleague asked me about pixel-oriented plotting in VPython, for doing
> such things as chaos-related plots. I replied that there really isn't
> good support for that in the production version of VPython, though the
> new "points" object in the beta version is appropriate.
>
> But then I realized that there is something one can do: Create a stack
> of horizontal lines (curve objects) and set colors at points that way.
> It works, and in the contributed section of vpython.org there is now a
> little program pixelplot.py which makes a display of the famous
> Mandelbrot set. The program also checks to see whether there is a
> "points" object available and uses that, which is faster and simpler.
>
> There's a slightly tricky issue when using curves, which is explained in
> the documentation for curve. Colors are interpolated between points. So
> to make the right color at a point, you have to stick in an extra point.
> So 4 pixels requires 8 points on the curve: 0-1, 1-2, 2-3, 3-4.
>
> Bruce Sherwood
>
> P.S. In the process I found that there are bugs in the points object. It
> dies when you try to append more than 33000 points. Dunno why yet. But
> this doesn't affect the posted program.
>
>
>