At last!
I suppose I've probably spent more time thinking about doing this than
actually doing it, but here it is at last.  Only took me a couple days to
put it all together from scratch, but then my hard drive is littered with
failed attempts...
I posted a 2-d version of this a while ago and haven't worked on the project
at all since then, but this 3-d version is a big improvement in many ways. 
This is a 40x80x40 grid and only takes a matter of ten seconds or so for
each simulation step.  (well, this animation is only every fourth
simulation step so it isn't so slow, but it could be with much bigger time
steps.)  I didn't really feel like waiting, so there is no scattering here,
just emission and absorption since it takes longer to render than to
simulate.  It's entirely based on the Visual Simulation of Smoke paper
found at http://graphics.ucsd.edu/~henrik/papers/smoke/ .  This version
adds has three dimensions of course, a much quicker generalized
perconditioned conjugate gradient solver (so it shouldn't be too hard to
add viscosity and diffusion), and although it has the beginnings of
boundary conditions built in, I haven't set it up to use that at all.  This
time I might actually post the code, since more experience means I'm
starting to be more proud of the code than ashamed (have mercy--this really
is the only c++ project I've ever worked on! [except for some stupid little
cloth thing]).  That said, there sure isn't a GUI and changing any
parameters means recompiling.  Maybe if I get it a little more complete and
comment the heck out of it, someone else could help out.  Well, bedtime for
me.

 - Ricky

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Attachments:
Download 'fluid.mpg' (185 KB)

Wow, thats damn nice and even for a small grid it looks more realistic than
everything i've seen till now. I tried to understand the article posted by
You but, well as i told before, i have no sense for mathematics. Please
give us an insight into Your knowlegde and provide us the source.

Best wishes and keep on doing stuff like that.

Shu.

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Shurakai wrote:

> Wow, thats damn nice and even for a small grid it looks more realistic
> than everything i've seen till now. I tried to understand the article
> posted by You but, well as i told before, i have no sense for mathematics.
> Please give us an insight into Your knowlegde and provide us the source.

Thanks.  It's taken me quite a while to understand the article, and that
includes plenty of stops at the library, searches online, and a couple
calculus courses.  Maybe by the time I get to the fluid dynamics courses
I'll have some idea what's going on...  Don't worry though--you'll get the
source.  Just be patient.  Trust me though; you wouldn't want it in its
ugly, uncommented form.  I'll post another, much better animation too once
it's done simulating and rendering.  It looks uncannily like theirs, but
good nevertheless.

 - Ricky

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Awe-inspiring. Truly amazing.

Can you blow a smoke ring with that sucker? (i.e. a sort burst of steam
through a round hole in the front of a drum) It looks as though it has
enough complexity to develop and sustain a vortex ring, there are the
beginnings of one in the posted animation, but I'd love to see if you could
make one with an existing system (w/o adding support for it, I mean).

-S
5TF!

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stm31415 wrote:

> Awe-inspiring. Truly amazing.
> 
> Can you blow a smoke ring with that sucker? (i.e. a sort burst of steam
> through a round hole in the front of a drum) It looks as though it has
> enough complexity to develop and sustain a vortex ring, there are the
> beginnings of one in the posted animation, but I'd love to see if you
> could make one with an existing system (w/o adding support for it, I
> mean).

Thanks!  Can I set up the conditions such that a smoke ring should be blown? 
Sure.  No problem.  Can I actually get a smoke ring out of it?  Hmmm... 
Doubtful, but I'll try it sooner or later.  Take no offense on the later;
I'm just busy.  Plenty of time to set something up and let 'er fly, but not
enough time at the moment to fine-tune something like a smoke ring.  On
that note, and on a bit of a tangent, I just think it's kind of ironic that
I didn't really do my differential equations homework or study for the test
because I was too busy... solving differential equations.  Oh well.  I
suppose there's no time like the present to do some real studying.  Oh, and
once I get it put together a little more, I'll post the code so you'll be
able to give it shot too.

 - Ricky

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Ricky Reusser wrote:

All I can say is Damn that looks nice! It really looks like something 
produced by a professional particle simulations package! Or something 
produced for a graduate level Comp sci paper!

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Thomas Lake wrote:

> Ricky Reusser wrote:
> 
> All I can say is Damn that looks nice! It really looks like something
> produced by a professional particle simulations package! Or something
> produced for a graduate level Comp sci paper!

Thanks!  Just keep in mind it isn't a particle simulation -- It's a
grid-based simulation imported into pov-ray via df3 file.  Theres a new
animation posted that should show a little better what it's capable of. 
This first one was just a test to make sure things were working right. 
Still not quite sure about the vorticity confinement.  Thanks though!

 - Ricky

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This is really amazing!
May I know whether you just use Povray to render the smoke? Do you use
photon map?
Because I have never seen so realistic smoke images rendered with Povray. I
used to think that Povray is not good at rendering smoke.

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Ricky Reusser <no_### [at] nowherecom> wrote:

> I posted a 2-d version of this a while ago and haven't worked on the project
> at all since then, but this 3-d version is a big improvement in many ways.
> This is a 40x80x40 grid and only takes a matter of ten seconds or so for
> each simulation step.  (well, this animation is only every fourth
> simulation step so it isn't so slow, but it could be with much bigger time
> steps.)  I didn't really feel like waiting, so there is no scattering here,
> just emission and absorption since it takes longer to render than to
> simulate.  It's entirely based on the Visual Simulation of Smoke paper

Very impressive.. I know this is a bit of an old post, but would you mind
explaining a bit how the rendering was done? I have been looking at doing
realisting raytracing rendering on numerical simulations we run here...
We're able to do some volume rendering, but *nothing* that looks as good as
what one would get from a 'real' raytracer.

I am a POV-Ray newbie, however, so any pointers as to where to
look (i.e. data format, etc) would be MUCH appreciated.

Thanks, and congrats. Very good work.

Charles

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