Severi Salminen wrote:
> I don't know. I think these are different things.

  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?

>>   In principle a BRDF is quite simple: It's a function which takes an
>> incoming direction vector and an outcoming direction vector as (const)
>> parameters, and returns a factor for each color component between 0.0
>> and 1.0. That's it. Its usage is equally simple: When you have
>> calculated a ray which intersects a surface and want to reflect that ray
>> to some direction, you shoot that reflected ray and then multiply the
>> color returned by that ray with the factor returned by the BRDF of that
>> surface. This will be the color returned by the original incoming ray.
> 
> I think that is not the best way to implement it.

  I didn't say anything about which direction the reflected ray should
go. The BRDF doesn't care.

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

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