.... no, don't panic - I'll keep working on the radiosity as such.

But I definitely give up trying to get 3.7 radiosity exactly reproduce 3.6
functionality.

I have dug through the code multiple times, discovered several discrepancies
between 3.7.beta.29 and 3.6 causing differences in output, identified several
others that didn't seem to make a change, stumbled across some old flaws I
intend to fix, and for sentimentality's sake even re-introduced one flaw that
wasn't there in 3.7 due to slight differences in the software architecture
(don't worry, I'll take it back out again :)), all to try and re-create the
same output as 3.6.

I have come to the point now that plowing through the whole code over and over
again has ceased to surface any further discrepancies. And I definitely do
*not* intend to go through *all* the POV code and revert it back to exact 3.6
functionality (and after all, maybe some modifications may actually be in there
for good already :)).

So I conclude that any residual differences must be rooted in changes to some
other parts of POV-ray code: Media, photons, area lights, multi-layered
textures - whatever.

The remaining discrepancies with the scenes I used for testing are:

- minor difference in brightness on one of the cube's corners in "cornell.pov"

- differences in brightness on the object-mapped portion of the pill containers
in "object_pattern.pov"; tests strongly indicate that these are caused by the
object-mapped texture, not the radiosity per se

- differences in brightness of various shadowed parts in "balcony.pov"; tests
were not conclusive about the true origin of the differences.

- differences in a self-made scene designed to provoke black-splotch artifacts,
probably related to differences in trace-level counting (note that the
black-splotch artifacts will be eliminated anyway)

- differences in another self-made scene (the "Claustrophobia" shot), probably
related to black-splotch artifacts and therefore of similar origin

- totally different results with a self-made, very demanding radiosity scene
which hasn't actually worked as intended with any POV version at all - again,
possibly due to differences in trace-level counting.


From what I see, none of these differences do any general harm to the picture
(except for the pill-container issus); the pictures simply look different, and
I find it hard to judge which version is more realistic. I'd usually prefer the
new output.


Aside from visual differences, the most notable ones are differences in speed.
Compared with the MegaPOV 64-bit Linux binaries, some scenes take a bit longer
with the current code, some render a bit faster. It seems that overall,
radiosity-only scenes benefit, while non-radiosity scenes all render slightly
slower, and mixed scenes are somewhat indecisive. This is all pure CPU time
though, and real-time speed benefits a lot on multicore systems.


If it was my call, I'd say let's just fix the black-splotch thing, get a few
details more towards the original Ward paper, make a new beta of it, and see
what reports come in.


Main remaining issues:

- Loading/saving of radiosity samples simply doesn't work yet

- Radiosity shots are currently not 100% reproduci... duca... um... I mean, you
can't reproduce the 100% same result on every run.

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