[Radiance-general] mixfunc for dichroic film?

[Giulio Antonutto]

I tried simulating caustics in Radiance classic (3.6a) by using mixfunc
(mirror + plastic with pattern)
I realized that Radiance does not look for virtual sources into mixed
definitions:
could you confirm that?

cheers,

giulio


PS sorry for the slightly different topic, it is just another mix-question
to add...



-----Original Message-----
From: radiance-general-bounces at radiance-online.org
[mailto:radiance-general-bounces at radiance-online.org]On Behalf Of Greg
Ward
Sent: 01 March 2004 17:10
To: Radiance general discussion
Subject: Re: [Radiance-general] mixfunc for dichroic film?


Hi John,

Another argument for using the BRTDfunc or transfunc types is that they 
don't require new ray evaluations for each new material type, which is 
a penalty you pay when you blend materials with a mixfunc.  Although it 
is tempting, you really should avoid using mixfunc with materials 
unless there really is no other way.  Originally, mixfunc would only 
blend patterns and textures, and this is still its primary purpose.  
However, using mixfunc as a this-or-that switch with materials doesn't 
incur the same penalty as smoothly blending them, because only one or 
the other material is ever evaluated.  If one of the materials is 
"void," you can get a kind of selective absence of a surface, which can 
be useful for screen doors, gratings, etc.

I'm not familiar with dichroic materials in an architectural context.  
Can you be more specific as to the behavior you wish to simulate?

-Greg


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