Roland Mas wrote in message ...
>"Peter Popov" <pet### [at] usanet> writes:
>
>> <snip>
>> Still, please try to spare some brain clock cycles on this.
>
>  I already did, but I guess you were just a little faster than I was.  All
>you say seems almost natural to me, even if I had not formulated it clearly
>yet.  Except that I was only using real faceted objects (like the actual
>discobll), and I had not thought of using the tangent plans.

Well, the first time I ever thought about this problem was maybe three years
ago. It took me about three hours to work out the math... for a
triangle-based rendering engine. It's a piece of cake, really. However,
when it comes to tesselating CSG-ed high-degree polynomials, blobs,
or julias, I am definitely not your man. It was just a week ago that I
realized/realised I could sample the light source and not tesselate the
object.

The described algorithm is also suitable for true refractive caustics. The
difference is subtle and is in the generation and usage of V[1..n]. Sample
ray m hits O, refracts, hits it again at Pm, and leaves as m1 (that should
be "m prime"). Vm lies on the reflection of ray m1 in Pm (but where exactly?
I'll think of it) and it's color and brightness depend on two more
parameters of O: internal media scattering & absorption and light
attenuation of O (fade_distance, fade_power).

>> That's it, put as clearly as I could. I would really to see your comments
on
>> this (especially the ones like "You know, Pete, this might just work!
I'll
>> try and code it tomorrow..." <G>)
>
>  You know, Pete, this might just work.  If I had time...  I currently have
>a running image, a big include file and a Python / Tkinter GUI...  And some
>"real work" too.  Too bad.

Glad to hear that, especially after you've been thinking along the same
lines for some time. Maybe we should move this thread to the programming
group and ask some of the code gurus there for ideas.

>  By the way, do you still need the .df3 library?  Now I have my PC, and I
>can code it someday...  Maybe even this week-end.  If of course it is going
>to be used (I won't use it myself before a looong time).

No bother, I'll do it myself. I'll be taking C++ this year anyway and this
will be a nice excercise. What was it, file i/o and basic voxel operations
(getVoxel, setVoxel)? Maybe a .df3 class will be best, esp. for a multi-doc
app. I'll give it a shot once I get a little more familiar with VC5.0

>Roland.
>--
>Les francophones m'appellent Roland Mas,
>English speakers call me Rowlannd' Mass,
>Nihongode hanasu hitoha [Lolando Masu] to iimasu.
>Choisissez ! Take your pick ! Erande kudasai !

Peter

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