> 
> I'm new in POV-Ray and 3D-arts in general. While working with the docs
> which came with povray I noticed that when the tutorials was talking
> about cubic_patches it adviced to use a program like moray. Since I'm
> interested in the whole stuff, including the handcoding I would like
> to know more about how to use this w/o any other program.
> 

I'm not using bicubic patches very much and don't know much about them,
but the first paragraph in the docs says most things: 16 control points
define a surface that is approximated with smooth triangles.  

IIRC the control points are connected in a regular grid:

+-----+-----+-----+
|     |     |     |
|     |     |     |
+-----+-----+-----+
|     |     |     |
|     |     |     |
+-----+-----+-----+
|     |     |     |
|     |     |     |
+-----+-----+-----+

The coordinates of the control points are used to form the patch similar
to cubic splines in 2 dimensional space.

furthermore:
http://www-personal.umich.edu/~jeffab/bicubic.html
http://www.icg.informatik.uni-rostock.de/Lehre/CG1/Geo/bezier_pov.html

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
Homepage: http://www.schunter.etc.tu-bs.de/~chris/

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