Re: [Algorithms] Scaling Models

[Jim O. <j.o...@in...>]

I think OpenGL handles normals in the same way (and if I am not mistaken,
OpenGL also uses some sort of inverse transform on normals, instead of
feeding them to the 'normal' pipeline, which I presume is to counter the
effects of scaling etc. on the normals...)

Jim Offerman

Innovade
- designing the designer
----- Original Message -----
From: "Peter Warden" <Pet...@vi...>
To: <gda...@li...>
Sent: Friday, July 28, 2000 12:18 PM
Subject: RE: [Algorithms] Scaling Models


>
> <snipped stuff about scaling and normals>
>
> Just out of interest, one thing I did a while back when I needed to treat
> both normals and vertex positions uniformly when applying an animation
> matrix to them was set the W component of the normals to 0, whilst leaving
> the W component of the positions at 1. This worked because the animation
> matrix never contained a scale, and I just wanted to not translate the
> normals. Is this a well-known technique that I just haven't run across
> before, and is there any theoretical basis for it?
>
> Peter Warden
> Visual Sciences
>
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