El mar, 13-11-2012 a las 20:58 +0100, Bernard LUCE escribi?:
> load(draw)$
>
> draw3d(implicit(x^2+y^2+z^2+8.75=6*sqrt(x^2
> +y^2),x,-3,3,y,-3,3,z,-.5,.5));
>
>
>
> inconvenience : no smooth appearence. Which options can
> improve that ?
x_voxel, y_voxel, and z_voxel. But implicit surfaces are generally too
slow.
>
>
>
> 2? with cartesian parametric coordinates :
>
>
>
> draw3d(parametric_surface((3+.5*cos(a))*cos(t), (3
> +.5*cos(a))*sin(t), .5*sin(a), a, 0, 2*%pi, t, 0, 2*%pi) );
>
>
>
> inconvenience : smooth surface but z-axis strechted and
> finally distorted appearance. Same question ?
>
>
>
> 3? with cylindrical coordinates :
>
>
>
> draw3d(cylindrical(3+sqrt(0.25-z^2),z,-.5,.5,az,0,2*%
> pi),cylindrical(3-sqrt(0.25-z^2),z,-.5,.5,az,0,2*%pi));
>
>
>
> inconvenience : the same as 2?
In cases 2 and 3, the option to be used is proportional_axes,
draw3d(
proportional_axes= xyz,
parametric_surface(
(3+.5*cos(a))*cos(t), (3+.5*cos(a))*sin(t), .5*sin(a),
a, 0, 2*%pi, t, 0, 2*%pi) );
or you can make use of zrange to set the z-scale by hand.
For coloring surfaces, take a look at
http://riotorto.users.sourceforge.net/gnuplot/colorsurf
--
Mario