"Thomas de Groot" <tDOTdegroot@interDOTnlANOTHERDOTnet> wrote in message
news:4a1e9c33$1@news.povray.org...
>
> "Chris B" <nom### [at] nomail com> schreef in bericht
> news:4a1e7ec8@news.povray.org...
>>> And presumably you're using either catenaries or a
>>> full mechanics simulation to produce hanging curves...?
>>
>> Ahh! Nothing nearly so sophisticated there I'm afraid :-). I have a loose
>> segment macro ....
>
> For catenaries, there is a set of macros by PM2Ring (2005)
What a tough assignment that turned out to be ;o)
I couldn't quite get my head round the approach that PM2Ring took, so I
spent the weekend swotting up on the maths (with long breaks for the
headaches to subside), and worked out a way to just use the most rudimentary
catenary formula. So it uses the value of 'a' to control the shape, which is
the ratio between 'H' (the horizontal component of the tension in the rope)
and 'w' (the weight per unit length).
The method used by PM2Ring has the advantage that you can specify the ratio
between the straight-line length and the rope length to control the amount
of sag in the rope, which is probably more intuitive than using 'a'.
Nevertheless, I plan to finish the documentation and post the first version
of the code in a couple of days. Then if anyone can improve on it we could
incorporate that in a future version.
So here's the result. An image of the catenary juxtaposed behind my original
with 'fake' gravity.
Regards,
Chris B.
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