"Mike Williams" <nos### [at] econymdemoncouk> wrote in message
news:TIA### [at] econymdemoncouk...
> Wasn't it David Cameron who wrote:
> >
> >Thanks very much Mike,
> >I went with your param.inc version. It works treat and is pretty fast.
> >I will need to use several of these in some scenes, so parse time could
go
> >up while the meshes are created, but I can live with that and I am just
> >happy to have found a solution :)
>
> Did you know that you can re-use the meshes if you happen to want ones
with
> the same dimensions? Even if they are in different scene files?
>
> If you pass param.inc a filename, as show below, it will look to see if a
> file of that name exists, if not it will create the mesh from the supplied
> parameters and write a file containing the mesh data. If the file already
> exists, it ignores the other parameters and reads the mesh directly from
the
> file, saving all that parse time.
>
> #macro elliptical_torus( x_major_radius, z_major_radius,
>   minor_radius, filename)       // changed here
>   #declare Fx = function(u,v){cos(u)*(x_major_radius+minor_radius*cos(v))}
>   #declare Fz = function(u,v){sin(u)*(z_major_radius+minor_radius*cos(v))}
>   #declare Fy = function(u,v){minor_radius*sin(v)}
>
>   #include "param.inc"
>
>   object{
>     Parametric(
>        Fx, Fy, Fz,
>        <0,0>,<2*pi,2*pi>,
>        100,40,filename          // and here
>     )
>   }
> #end
>
> Call it like
>   object {elliptical_torus(2,1,0.4,"ET2_1_04.DAT")
>     texture {...}
>   }
>
> You just need to be careful to change the filename when you change any of
> the other parameters.
>

I would be using several elliptical torii of the same dimensions so this is
great to know.
Now, if only I can solve the "inside_vector" problem.

Thanks again,
Dave

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