I pride myself on being able to explain anything, but John VanSickle explains
the Matrix better than I ever could. Take a look at
http://users.erols.com/vansickl/matrik.htm for more details



> Thanks a bunch! I finally understand the transformation matrix. The
> documentation isn't very good.
>
> Josh English wrote:
>
> > There is a standard orientation macro that looks like this:
> >
> > #macro Orient(v1,v2)
> >   #local nx = vnormalize(v2 - v1);
> >   #local nz = vnormalize(vcross(nx,y));
> >   #local ny = vcross(nz,nx);
> >   matrix <nx.x,nx.y,nx.z,
> >           ny.x,ny.y,ny.z,
> >           nz.x,nz.y,nz.z,
> >           v1.x,v1.y,v1.z>
> > #end
> >
> > This only works if the object "faces" the positive x axis... so you might
> > want to rotate your torus by 90*z before including the macro:
> >
> > torus { 1, 0.25 // or whatever
> >             rotate 90*z
> >             Orient(thisvector, thatvector) }
> >
> > It is possible (and I've don't it before but I don't have the file handy)
> > to rearrange the first three lines of the macro that will make the
> > rotation command unnecessary.
> >
> > Good Luck
> >

--

Josh English
eng### [at] spiritonecom
ICQ: 1946299
"Stress is when you wake up screaming and realize you haven't fallen asleep
yet."

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