POV-Ray : Newsgroups : povray.text.scene-files : Tangents between circles : Re: Tangents between circles Server Time
21 Sep 2021 05:14:13 EDT (-0400)
  Re: Tangents between circles  
From: Bald Eagle
Date: 17 Nov 2019 20:20:01
Message: <web.5dd1f0a31b345bf54eec112d0@news.povray.org>
"jr" <cre### [at] gmailcom> wrote:

Right-o.   I just got a quick demo scene posted before it dropped off the
back-burner.


> for the 'pulleys', in addition to centre + radius, having a texture would be
> cool.  either as a "parallel" array, or perhaps using the new mixed array type.
> now wondering how one could prepare for/support animation.

Well there's no reason that can't be appended to the scene.
Just make a cylinder or disc right below the circle array.
Or a separate texture array that will use the current loop value in the arc/line
plotting section.

> if a start and end point get specified, that would get a "cable", while no
> points would be a "belt", ie closed.  either way, the belt/cable goes around a
> pulley either clockwise or counter (a boolean), so could be represented as an
> array of floats for automatic "routing", 'N.0' for clockwise and 'N.1' for the
> reverse, where N is the pulley array index.

There are two portions of the post-calculation section.   one to make the
bezier-arcs, one to make all 4 (if they exist) tangents.
I have oh-so much of that in the developmental "full" version.   The logic and
flags and texturing is bewildering, thus, the cut-down version.
See the original developmental renders with the colored lines, arcs, and the
color coded oriented/Boolean directional final belt path.

> anyway.  will be happy to do testing and help document, and what other (small)
> help I can give.

I'd say that the best help at the moment might be to just look it over and do a
parallel implementation, starting from what I posted.   That would give me new
ideas for how to process the data, and other things with what to do with the
results that I might not have thought of yet.

Also, asking any questions you may have about specific bits of the code would
help me document it, and in the process re-read and re-think what I've already
done.

Certainly I'd love to work out the logic of animating it, and doing something
like a toothed belt or chain to run along gears or sprockets.

I haven't done much pathological case testing, because it's already a miracle
that it even works at all.


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