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Re: Very slow graphics rendering
*To*: mathgroup at smc.vnet.net
*Subject*: [mg14179] Re: Very slow graphics rendering
*From*: Paul Abbott <paul at physics.uwa.edu.au>
*Date*: Wed, 30 Sep 1998 02:04:25 -0400
*Organization*: University of Western Australia
*References*: <6unfa9$o75@smc.vnet.net>
*Sender*: owner-wri-mathgroup at wolfram.com
julio vera wrote:
> With their help, I could make a graphic of part of a 3D object, like
> this piece of a sphere:
>
> ParametricPlot3D
> [{x , y , If[ x^2 + y^2 < (4/5)^2 , Sqrt [ 1 - x^2 - y^2 ] ] } , {x , -1
> , 1 , 1/75} , { y, -1 , 1 , 1/75} ]
For such a function you could use Plot3D directly:
Plot3D[If[x^2 + y^2 < (4/5)^2, Sqrt[1 - x^2 - y^2],
Sqrt[1 - (4/5)^2]], {x, -1, 1}, {y, -1, 1},
PlotPoints->30,Mesh->False];
However, an alternative (polar) parameterization might be better:
ParametricPlot3D[{r*Cos[t], r*Sin[t],
If[r < 4/5, Sqrt[1 - r^2], Sqrt[1 - (4/5)^2]]},
{r, 0, 4/5}, {t, 0, 2*Pi}];
Cheers,
Paul
____________________________________________________________________
Paul Abbott Phone: +61-8-9380-2734
Department of Physics Fax: +61-8-9380-1014
The University of Western Australia Nedlands WA 6907
mailto:paul at physics.uwa.edu.au AUSTRALIA
http://www.physics.uwa.edu.au/~paul
God IS a weakly left-handed dice player
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