Shadow transperancy problems 2004-04-06 - By Thomas Moffat Grimes
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Hi John,
The answer is that for transparency to work, you need to use Raytracing.
Shadow Maps can't determine transmission in glass-like materials,
transparency, or alpha maps. Turning on Shadow Transparency forces the light
type to be Raytraced, which is why you lose your soft shadows from Shadow
Map option (as it gets turned off).
The solution is to create soft shadows using raytracing. There are numerous
ways to do this. The most common is to use an array of lights, all casting
raytraced shadows. You can create your own array, or use the Area light or
IBL light (in the case of an IBL just scale it really small to act as a
small array, like a point light source that will give you soft shadows).
Render times will go up in general, as raytracing shadows tends to take
longer, but this is the only way to get soft shadows from alpha maps.
HTH!
Tom
Thomas Moffat Grimes
Marketing Communications
Caligari Corporation
mailto:thomas@(protected)
http://www.caligari.com
-- --Original Message-- --
From: Visual Impact [mailto:visualimpact@(protected)]
Sent: Tuesday, April 06, 2004 3:13 AM
To: truespace@(protected)
Subject: [TSML] Shadow transperancy problems
I am having trouble with turning shadow transperancy on for a shadow
casting light.
I start off with nice shadows with soft blurry edges, but as soon as I
turn on shadow transparency I get harsh defined edges for the shadows.
I want to keep the soft shadows but still have my alpha masked planes
cast shadows.
Can anyone shed some light on this.
John Butcher
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