In article <38f1b7da@news.povray.org>, Warp <war### [at] tagpovrayorg> 
wrote:

>   What could be done with the shader not possible with pigment functions
> (which are going to be included in pov3.5 most probably)?

One example of something that might be possible is a good starfield that 
is resistant to anti-aliasing. Or possibly textures that anti-alias 
themselves, or blurred reflection that is only blurred in specific 
directions...
You could also test out new highlight models like blinn with a shorter 
development cycle, and if they are popular enough, they could be 
incorporated into the program later.

Like I said before, shaders are to textures as isofunctions are to 
object primitives(and patterns!). They are much more than a pattern 
function, they can handle specialized reflection/refraction/media etc.
A pattern function is actually kind of like a partial shader, or a 
shader specialized and restricted to patterns. As a matter of fact, one 
possibility for implementing a kind of shader would be to use 3 
functions, one for red, green, and blue, and adding functions like 
trace(), eval_pigment(), etc. This would probably be a bit easier to 
use, and would have a syntax more consistant with the rest of POV-Ray, 
but would not be able to use existing RenderMan shaders and would 
probably be less flexible.
Maybe the two are not mutually exclusive, though...it might be possible 
to make a shader patch with an easier to use POV-like syntax(based on 
isofunctions) as well as support for RenderMan type shaders.

-- 
Christopher James Huff - Personal e-mail: chr### [at] yahoocom
TAG(Technical Assistance Group) e-mail: chr### [at] tagpovrayorg
Web page: http://chrishuff.dhs.org/

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