A neat effect seen in 3D-Engines are particle effects which
add to each other. So, what the Engine does, is take point in
space, check if a certain disc around it isn't blocked, and then
just add a certain RGB-Component to the "rendered" image
from the engine.
The effect is much like emission-media, which just "adds" color
on top of the background, whereas absorption-media "subtracts".
The problem is speed. To get faily smooth "discs" (got to use spheres),
POV needs a pretty high sample rate.

Though I know, POV isn't a 3D-Engine, doesn't do scanline and
all the typical answers we get... We have transparent and filtering
"channels". Isn't it possible to somehow add an "adding" channel?
Negative values could subtract, much like absorption, and positive
values add, much like emission.
In have no idea about the handling of colors and such in POV's
workings, but a guess would be to add this feature by making use
of the way media-attenuation is stored... That's just a guess!

I'm not too sure if the proposed idea is actually possible within
the "confines" of POV-Ray 3.5... Nontheless, has anybody got
any good ideas how this may be made possible with "common"
3.5 techniques (aside using the tracing-intensive media)?


--
Tim Nikias
Homepage: http://www.digitaltwilight.de/no_lights/index.html
Email: Tim### [at] gmxde

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