Hello...

1 - I use PoV 3.1 to model various astronomical phenomena (animations
to be soon on the WEB...), and general physics phenomena for education.
I recently modelled (artist's view only, as only a rough sketch
of the physical processes is available !)
the central parts of an active nucleus galaxy (the thing with a black
hole in the center), made it rotate, and so on. Nice, but it rotates as
a solid
object, which is wrong. Does anybody know of a way of "warping"
continuously the "spiral" texture to make it rotate faster in the
central
parts than in the outer parts ? I searched a lot in the (excellent)
in-line doc, with no success...  Maybe I missed something...

2 - I am going to try to write an external program computing a B-spline
approximation to a set of points ( two sets in fact, one for the camera,

the other for the "flying object" ) The best way I know so far is using
PCG2.21 (Patrick's Curve Generator), which takes as input the clock
variable
and a spline.dat ASCII file containing the knots of the path, and
outputs
an ASCII file wtih a set of #declare. The whole thing is invoqued via a
Pre_Frame_Command in the .ini file. This is the structure which is
planned for the code I am about to write. But the PGC program does not
compute the local curvature and twist of the 3D spline, which are needed
to
compute the "correct" attitude of the plane, and cannot compute two
distinct
spline approximations on two data sets for the same clock value.
The "spline" add-on from Chris Colefax is not well suited for multiple
knot
splines, as you must give all the control points to be used for all the
knots;
or did I miss something ?
I tried AnimSys, too, but the "plane" attitude is not computed from the
fly path shape, just given a priori.
Before engaging further into  development, I would like to know
if anybody heard about something addressing this problem...
It should have been solved by all the people working in the flight
simulation
area...

3 - I used (before switching to the last release of PoV for Windows) the

dispersion patch. I was able to render all kinds of gems, to demonstrate

refraction into complex objects during physics courses. Great, but I was

not able to obtain a spectrum-like patch of light on a screen following
a glass ball, although I got nice effects in the ball itself.
Is that normal, or just a matter of wrong code ?
I tried to disperse light through a prism, and get a spectrum on a
screen :
no result...

Many thanks to the fabulous POV team !

Gilles AdamObservatoire de Lyon
69561 Saint Genis Laval cedex
France
ga### [at] obsuniv-lyon1fr

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