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Re: Polygons on spheres


Hi,

a) Mathematica uses PostScript and PostScript can't display
   transparence
b) MathGL3d can do this, if you send me the code
   I will do it for you
c) Michaels books are excelent and you should buy one for you
   and several copys for your friends

Regards
  Jens


"Steve Gray" <stevebg at adelphia.net> schrieb im Newsbeitrag 
news:cvukq6$bdq$1 at smc.vnet.net...
> I have a need to draw and display "polygons" on spheres. The edges of the 
> polygons will all
> be arcs of great circles. Examples are triangles, etc., and n-sided 
> polygons which usually
> self-intersect. The great circle arcs must stop at the vertices, which 
> presumably can be done by
> correctly setting the range in the parametric plots of the edges. 
> Obviously several edges must be
> displayed at the same time, up to a dozen or two.
> I want to see what these figures look like when the vertices are moved 
> around on the sphere,
> probably one at a time, constrained by certain rules.  I would like to see 
> the sphere as a colored
> surface with the lines standing out. I can specify the vertices by 
> theta-phi or whatever. My main
> concern is getting a good display, not the actual math. I will need to 
> vary the point of view to
> look at different parts of the sphere and maybe make an animation.
> The part I'm uncertain about is getting a sphere and the lines to show at 
> the same time, and
> how to choose whether the lines on the back side of the sphere are visible 
> or not, so options should
> be transparent vs. translucent vs. opaque sphere.
> Any suggestions will be welcome. Does anyone know if Trott's book on 
> Mathematica display coding
> covers this? If it will help, I'm willilng to buy it.
>
> Steve Gray
> 



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