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Re: [Groff] Manuals in pdf format

From: Tadziu Hoffmann
Subject: Re: [Groff] Manuals in pdf format
Date: Fri, 3 Mar 2006 11:35:06 +0100
User-agent: Mutt/1.5.11

> Now the beauty of the thing is, that when you rotate a body,
> you rotate the normal vectors as well.  When you translate
> or scale, you translate and scale the vertices, but not
> the normals.  Now these "Whew!" guys transform the normals,
> always.

If you scale the body anisotropically, you *have* to transform
the normals, otherwise they wouldn't be normal anymore.  (And
you have to transform them differently from how you transform
the vertices, that's what they're saying. Think covariant and
contravariant vectors.)

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