[fluxus] turning objects inside out

[Dave Griffiths]

> Hi all,
>
> I tried to do...
>
> (scale (vector -5 -5 -5))
> (build-sphere 8 8)
>
> ...and just got a weird halo, and nothing visible when I move inside the
> sphere, so I'm wondering why it doesn't work.

The normals are scaled too - which means they are still facing outwards,
so you get an inside out sphere, but all the visible faces have normals
more or less facing away from the camera light (less so on the edge). You
can manually flip the normals to get it lighting correctly, or...

> and more pertinently how to create the 'background' type effect seen in
these example images:

you probably want (hint-unlit) for background sky sphere type shenanigans.

> http://www.pawfal.org/nebogeo/images/fluxref1.png
> http://www.pawfal.org/nebogeo/images/fluxref2.png
>
> The reflections would be nice, too, but not if it's too hard to
> implement or too slow to render.

See example 10b. I don't think the reflections are technically correct
(IIRC I wrote that script on the train on the way to make art :) ), but
they look sort of how you'd expect. It's a per vertex operation so the
speed depends on the complexity of the model. It could probably be sped up
if the model isn't deforming as well.

cheers,

dave