In article <3A62BC0D.C65F3E08@xlstudio.com>, gemelli david 
<d.g### [at] xlstudiocom> wrote:

> yesterday, I started a POVMan shader to do an insect "shell" (not sure
> of the word).

"Exoskeleton", but people will look at you funny if you use words like 
that too much... ;-)


> 2 questions:
> - I'm not sure of my shader version of the "metallic" keyword... I
> multiplied the specular by the surface colour...Am I right ?

That seems to be an approximation...looking at the source code, POV 
seems to use some kind of Fresnel function for textures using 
"metallic". This is for both phong and specular...and apparently phong 
and specular are the only things affected by metallic, and the 
calculations do use the surface color, though it is more complex than a 
simple multiplication.


> - I'm using little spheres to do the big sphere. When I increase the
> radius of the spheres, the rendering time increase a lot ! Is it normal
> ?

When the spheres overlap more, POV has to solve for more spheres to get 
the one that is in front of the others. If you have 4 spheres 
overlapping in an area, all 4 will have to be computed to render that 
area. When you increase the radius of the small spheres, you increase 
the average number of spheres per pixel, and POV has to do more work to 
render the image.

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

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