Tor wrote in message
news:Xns### [at] 204213191226...
> Will wrote in news:3e8783bc@news.povray.org:
>
<snip>
> I have some ideas on how to define all the
> control points. It's quite simple, but I'm
> too tired to explain it right now.


Looking forward to hearing from you about this!


> > I am confused about the translation you are proposing-- I don't think
<snip>
> No. Here is an example of how you can rewrite
<snip>

Nice explanation. Thanks. I've tried this and I'm adopting the translation
idea as it does make the code cleaner (easier to maintain). To my mind the
scaling makes it harder for me to see what's happening-- I mean that when I
come back to this 6 months from now, I would have a more difficult time
relearning the code if I adopt your scaling concept. That just might be me
and my foibles, YMMV.

As far as optimization for speed, I was disappointed with both of these
techniques, and also with moving the array references into earlier
declarations as you had also suggested. Even when used all together, these
only speed up processing incrementally. Except on possibly a very large
patchwork, I'd need a fine stopwatch to see the improvement. Bummer.

OTOH, I've found that excluding the clipped_by segment speeds up processing
a very great amount. I'm wondering if the clipped_by is disabling POV's
implicit bounding box construction.

I'm going to spend a few hours playing with an alternate approach that might
get around the need for the clipped_by and also correct the uv_mapping
problems. If I can't do that, I'll see what happens if I construct an
explicit bounding box.



> Why don't you just scale down the pigment that
> is going to be used in the mapping (prior to
> the mapping).
>
> E.g.:
> If it is an image map, then you first translate
> the image map pigment so that it is centered at
> the origin, scale it and then translate it back.

For a one-shot, that would be acceptable to me. For a tool that I want to
use over and over again, and share with others, it is not. Either the macro
handles uv_mapping in the normally expected way, or it gets an attached
disclaimer that says uv_mapping is only supported to a limited degree.



--
Will Woodhull
Thornhenge, SW Oregon, USA
willl.at.thornhenge.net

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