Subject: negative lights, interesting features
From: [email-masked]
To: Multiple recipients of list <[email-masked]>
Date: Sun, 21 Apr 1996 19:00:58 -0700

On Sat, 20 Apr [email-masked] (Brenden Mecleary ) asks:

> Is there any way to make "remove lights" in LW5? ...a light that,
> instead of adding light to a surface, takes it away, creating
> a dark spot?

No. But...you can do some interesting things with surface attributes that may
not be immediately obvious.

For example:

- you can enter negative values for Specularity, thereby creating a dark spot
on the surface of objects. (This may give you the look you are asking for.)
- if objects are rendering oversaturated (or even if they're not), you can
enter negative values of Luminocity to bring the overall brightness of the
object down. (Particularly useful for image maps, which can easily get
oversaturated.)
- you can enter negative values for Diffuse, but this won't do anything more,
by itself, than a 0 diffuse. However, it may do something if the luminocity
is above 0 or the surface is affected in other ways.
- you can enter negative values of reflectivity. This causes the surface to
reflect the photonegative of the color it would otherwise reflect if the
value was positive.
- you can enter negative values of Transparency. If anyone can figue out
exactly what this does, please post to the list--I can't, except that it
seems to render the object inside out.

David Hibsher
Technical Writer, NewTek (who recommends thinking outside the square)