Warp wrote:

>   Of course you *can* perform brute-force rendering without using BRDFs.
> The point is that it doesn't make too much sense because BRDFs are the
> most accurate texture definition functions, while everything used in
> non-brute-force rendering is only an inaccurate approximation.
> Brute-force rendering allows using BRDFs, so why not use them?

Depending on definition, even POV-Ray is using BRDFs. Maybe I just don't
know what is your definition of "BRDF" when considering ray tracers.
(see below)

>   You can, of course, send more rays towards directions for which the
> BRDF gives larger factors.

And that is the best way to do it. Like I said, sending rays to all
direction when the material is 100% mirror, is not so clever.

The problem here is I have no idea, how the user would assign an
_arbitary_ BRDF to a object. What does it look like and how would the
program generate a distribution function out of it. Should it be just a
bunch of weight/angle pairs and the renderer interpolates and renders
accordingly? Or something else?

And of course, I use BRDFs even now if end result is considered. They
just look a bit different and are "special cases", like 100% diffuse
material, 100% specular surface etc, transmissive surface following
Snell's law etc. Luxrenderer also "uses BRDFs" the way I do. So maybe
I'm using BRDFs after all :)

http://www.luxrender.net/index.php?option=com_content&view=article&id=49&Itemid=59

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