It does seem strange to me as well. In the particle system I am working on,
I'm using smooth triangles as the particles. I calculate normals that point
at 90 degrees to the average normal of the triangle. These normals are
parallel to the surface and have had no error mesages like this.

Any programmer types who get into the POV code care to explain in detail?

Thanks
Gordon

david sharp wrote in message <36F### [at] interportnet>...
>Ken wrote:
>>
>> david sharp wrote:
>> >
>[ ... ]
>> > Now, my question is why does POV-Ray do that? What is wrong with
>> > one normal pointing 'up' while two point 'down' (or vice versa)?
>>
>>   In effect you are twisting it into a fourth demension when you have
>>  two normals pointing in the opposite direction of each other on one
>>  object.
>>
>
>fourth dimension?
>a ball doesn't have to twist into a fourth dimension to have
>normals pointing in *every* direction.
>
>Since Nathan Kopp posted that at least that one triangle was OK with
>POV-Ray 3.1a, I find this still mysterious.

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