POV-Ray : Newsgroups : povray.advanced-users : Phong BRDF pigment { function{} } : Re: Phong BRDF pigment { function{} } Server Time
26 Nov 2022 04:22:00 EST (-0500)
  Re: Phong BRDF pigment { function{} }  
From: Bald Eagle
Date: 14 Nov 2022 16:45:00
Message: <web.6372b69f6d24d701f9dae3025979125@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
 Since
> point lights seem to be an example of a Dirac delta function in this context, it
> almost seems like there ought to be a mechanism to force sampling from _those
> vectors_, or to explicitly block those vectors and do a second pass using
> standard phong highlighting.

So, this was an interesting read:

https://www.gamedev.net/blogs/entry/2261086-importance-sampling/

It seems that for point lights, the importance sampling algorithm just defaults
to the phong model.  They even invoke the same Dirac delta function description.
Spooky.

At the moment, I'm still at a loss as to how to code the variable BRDF sampling
modes, but knowing what to do (and what NOT to do) is usually over half the
battle.  Maybe more.


I'll keep searching, reading, and watching - and maybe I'll come up with some
way to implement this.


As a related aside, I think that we could probably use an importance sampling
approach to increase the efficiency of hit-or-miss style algorithms like filling
containers or placing objects in scenes, on specific terrain features, etc.
Likely other less obvious uses as well.


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