Alain <ele### [at] netscapenet> wrote:
> A work around for that problem:

(Hum... such things keep making me go, "why can't POV support this natively
instead of all these work-arounds?" I mean, it's not like this was something
exotic. Even it was just an SDL statement that under the hood would use the
same work-arounds, I'd still appreciate it.)

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"clipka" <nomail@nomail> wrote:
>
> > http://tag.povray.org/povQandT/languageQandT.html#blurredreflection
>
> [Read that] already a while ago.
>
> The averaged textures approach didn't stick though. Maybe because it's *fatal*
> if you have a lot of reflecting surfaces: The rays POV needs to trace will
> explode exponentially with each reflection.

That was exactly the problem I found.

> In contrast, if you do the averaging via multiple renders + post-processing, the
> number of rays is only increased by a constant factor; at each reflection, the
> number of rays multiplies only by the same amount as if the scene used sharp
> reflections.

And that's the same answer I came up with, and I also use the multiple passes to
do anti-aliasing, focal blur, soft shadows, lightdome IBL lighting and I'm just
starting to try putting media in there too. And the render time stays almost
constant with each new effect, as the "quality" for each comes from the
multiple renders you are already committed to.

> After the first blurred reflection, there's actually not much benefit in
> multiplying the number of rays even more.

If the POV team wants to keep the current way of allowing blurred reflection,
then I would suggest having some sort of reflection control to say how many
rays are propagated at each reflection. That way you could have 100 rays at the
first object, but only the first 10 of those reflect themselves. Sort of a
max_trace that varies based on whether the ray is reflection 1, 10 or 100.

Cheers,
Edouard.

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"clipka" <nomail@nomail> wrote:
> Alain <ele### [at] netscapenet> wrote:
> > A work around for that problem:
>
> (Hum... such things keep making me go, "why can't POV support this natively
> instead of all these work-arounds?" I mean, it's not like this was something
> exotic. Even it was just an SDL statement that under the hood would use the
> same work-arounds, I'd still appreciate it.)

Megapov added blurred reflection via a keyword a long time ago, but the patch
was never rolled back into POV as the averaged normals/textures trick did more
or less the same thing. Or so I've read - someone can correct me if I've
understood that wrong.

Cheers,
Edouard.

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clipka wrote:

> Even it was just an SDL statement that under the hood would use the
> same work-arounds, I'd still appreciate it.)

Furthermore, this would allow opimizations such as specifying
a max_trace_level for the blurred reflection (similar to the
corresponding cut-off in Mega-POVs light source), to prevent
excessive render times with little effect when the scene
contains other reflective objects.

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Edouard Poor <pov### [at] edouardinfo> wrote:
> If the POV team wants to keep the current way of allowing blurred reflection,
> then I would suggest having some sort of reflection control to say how many
> rays are propagated at each reflection.

  That sounds like something which could be done easily in POV-Ray 4 with
its new scripting/shader language.

-- 
                                                          - Warp

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