EnigmA Amiga Run 1997 July/EnigmA AMIGA RUN 20 (1997)(G.R. Edizioni)(IT)[!][issue 1997-07 & 08][EAR-CD IV].iso/lightwave/lwmlist/94.lightwave-07/000371_owner-lightwave-l _Fri Jul 22 12:40:43 1994.msg

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Subject: Re: Magnifying glass
In-reply-to: Your message of Fri, 22 Jul 94 07:53:25 -0700.              <[e-mail]>
Date: Fri, 22 Jul 94 14:04:35 EDT
From: Mark Thompson <[e-mail]>
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> Does lightwave deal with refraction only on a surface basis, so that
> the actual thickness of an object doesn't matter, only being affected
> by the surface normals?

In real life, refraction only operates on a surface basis, for the most
part at least. Basically, light only bends at the junction of two mediums
with different refractive indices. LightWaves duplicates this behavior
by only altering the beam path at the surfaces. The trick is, you want to
duplicate all your lens polygons with a different surface name and have
them all point in the opposite direction (ie. into the lens). The outward
pointing polygons have the refractive index of your material while the inward
pointing ones have the index of air. Do not enable double sided for either
surface. However, due to a bug in 3.0 and 3.1, you will have to set the air
index to something like 1.001 (rather than 1.0) for it to behave properly.
With these refraction settings, LW will see the outward pointing refractive
surface as it enters the lens, and then see the inward pointing non-refractive
surface as it leaves the lens, thereby properly modeling refractive behavior.
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