Ah ok, it's a function from "functions.inc". All understood now.

Many thanks,
Oleguer



news:NDqQ$LAVOUgBFw+H### [at] econymdemoncouk...
> Wasn't it Oleguer Vilella who wrote:
> >Hello Mike,
> >
> >Can you explain again how did you do this translation?
> >====================================
> >isosurface {
> >   function{DNA(f_r(x,z,y) ,f_th(x,z,y),z)}
> >====================================
> >What's f_r and what's f_th?
> >
>
> If you're not familiar with polar coordinates, I don't think I can teach
> the concept in a newsgroup posting.
>
> If you are familiar with polar coordinates, then f_r(), f_th() and
> f_ph() are standard functions (in functions.inc) which give you the
> polar coordinates R, Theta and Phi. On a globe, they would be altitude,
> longitude and latitude.
>
> By transforming a function from Cartesian (ordinary xyz) coordinates to
> polar coordinates we can bend the space that contains the function so
> that the grid lines of the space are wrapped round into circles.
>
> There are spherical polar coordinates (R Theta Phi) and cylindrical
> polar coordinates (R Theta z) and it's the second of these that I used
> for this scene.
>
> -- 
> Mike Williams
> Gentleman of Leisure

Post a reply to this message