Looking at Bill Pragnell's wonderful trefoil knot work, I wondered if 
the same ideas could be generalized to other, more complicated knots by 
using splines from KnotPlot, and orienting via Spline_Trace.

The answer seems to be yes and no.  There's evidently some sort of 
glitch with v3.6, when it comes to repeated (looped) calls to 
Spline_Trace (see the thread in pov.general.)  The attached image was 
made with v3.5.  The concern that makes it also not so simple is that 
for general splines, they do not cover a fixed curve length per unit 
time, so that, by using a simple "while" loop, some parts (of a 
stairway, for example) will get crunched together, while other parts 
will be stretched out.  I'm puzzling over a macro that will re-divide a 
spline to cover curve length at a steady rate (or has this already been 
done?)

Also, has anyone else noted the strange behavior of v3.6 and 
Spline_Trans?  Is it a known bug? or not a bug?

Dave Matthews

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