"Paul Blaszczyk" <3d### [at] alpharayde> wrote...
> Hello,
>
> it is possible to do a fast blurred reflection like the focal-blur?
> A mixture of z-buffer (depth-buffer?) and a kind of a "object-buffer"
> must be enought to mask the object after the rendering and blur this (i
> think 3D Studio is using a method like this...the blurred reflections
> looks kewl and they are very fast).

I'm assuming you're speaking of the scan-line renderer in 3DS (and not some
hybrid scanline/raytracer).  If so, reflections are created by rendering the
scene from the object's perspective.  This image, usuall referred to as an
environment map, is then mapped onto the original object.  The environment
map could be blurred using the z-buffer just like post-process focal blur.

POV, however, does not use an environment map for reflections.  Reflections
are computed on a per-intersection basis during the final rendering step.
Unfortunately, since there's no environment map, there's nothing on which to
do a pixel-blur.

One neat thing that could be done would be to keep the full ray/object
intersection tree during rendering.  If this were done, lots of cool things
(like quick-and-dirty reflection & refraction blurring) could be done.
Basically, you'd shoot a rays and store the entire tree.  Then, you'd
analyze what you had to look for things like ray footprints and stuff like
that.  Finally, you could start processing the info from the leaves towards
the root of the tree.

This, of course, would require LOTS of memory.  :-(

If this were worked into a modeller+renderer package, you could do all sorts
of cool things to ray-trace the scene as you work on it.  If you modify an
object, you'd just have to go through the tree and retrace only the rays
that intersect the bounding box (old and new) of the object.  The other rays
(and corresponding pixels) would remain unchanged.

You could probably also do some good stuff with radiosity calculations, too,
by analyzing the ray/objec tintersection tree before doing the radiosity
calculations.

Sure, there are a lot of things that I haven't thought through about this,
but I'm brainstorming out loud, so bear with me.  :-)

-Nathan

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