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Re: How to apply EdgeForm to ParametricPlot3D?


>  Hello.  Is it possible to apply the EdgeForm Graphics3D
>  directive to a surface plot done with ParametricPlot3D?
>  The Book says nothing to the contrary, but I haven't
>  found a way of getting it to work (i.e. ParametricPlot3D
>  *always* draws black edges on the polygons forming the
>  surface, regardless of EdgeForm directives).  Does anybody
>  know how to do it?
>  

>  Thanks in advance,
>  

>  Gabriel

Actually "The Book" does say something to the contrary in the sense that
MeshStyle is an option for Plot3D but not for ParametricPlot3D or Graphics3D.

EdgeForm is a Graphics3D primitive. Unfortunately, graphics primitives can  
never just be thrown naked into graphics commands.
(Unless you use calcE! See http://seuss.math.wright.edu/calcE/calcEHome.html or  
ask for further info.)

Anyway, here's one way to "do it". The result is a sphere with red mesh lines  
instead of black ones. (Nice!)

gr = ParametricPlot3D[{Sin[s] Cos[t],Sin[s] Sin[t],Cos[s]},{s,0,Pi},{t,0,2Pi}];
gr1 = Insert[gr,EdgeForm[RGBColor[1,0,0]],{1,1}];
Show[gr1]

To see why this works:
Short[InputForm[gr],5]
Short[InputForm[gr1],8]

The Insert command places the EdgeForm primitive at the beginning of the list  
of polygons.

Richard Mercer


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