After having been away from home for a week, I'm back now and I'm working on
my particle system again.

I have made linear interpolation of the particle locations, which means that
the particles now move smoothly also when the calculation frame-rate is not
a multiple of the render frame-rate. For example this animations has a
render frame-rate of 30 frames per clock-unit and a calculation frame-rate
of 20 frames per clock-unit.

This is an advantage for example if you have set up a particle system that
behaves perfectly in your test renders. For your final render you want a
higher render frame-rate but you want the particle system to behave exactly
the same, so you don't change the calculation frame-rate. The particles will
still move smoothly because of the interpolation.

I have also changed this preview animation mainly by using many more
particles, by making the blob elements more blobby and of course by
rendering at a higher resolution.

As always, comments appreciated!

Rune
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Attachments:
Download 'flow2.mpg' (145 KB)

Good work! I'm really looking forward to the code... (This is a subtile
hint.;-) )

Bugs74


"Rune" <run### [at] inamecom> schreef in bericht
news:3ab3eae6@news.povray.org...
> After having been away from home for a week, I'm back now and I'm working
on
> my particle system again.
>
> I have made linear interpolation of the particle locations, which means
that
> the particles now move smoothly also when the calculation frame-rate is
not
> a multiple of the render frame-rate. For example this animations has a
> render frame-rate of 30 frames per clock-unit and a calculation frame-rate
> of 20 frames per clock-unit.
>
> This is an advantage for example if you have set up a particle system that
> behaves perfectly in your test renders. For your final render you want a
> higher render frame-rate but you want the particle system to behave
exactly
> the same, so you don't change the calculation frame-rate. The particles
will
> still move smoothly because of the interpolation.
>
> I have also changed this preview animation mainly by using many more
> particles, by making the blob elements more blobby and of course by
> rendering at a higher resolution.
>
> As always, comments appreciated!
>
> Rune
> --
> \ Include files, tutorials, 3D images, raytracing jokes,
> / The POV Desktop Theme, and The POV-Ray Logo Contest can
> \ all be found at http://rsj.mobilixnet.dk (updated January 28)
> / Also visit http://www.povrayusers.org
>
>
>

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looking much better, although i would still say it neads many many more
smaller blobs :)

very impressive how you have managed to get it perfectly cyclic.

does a blobs behavour change acording to its size? - ie smaller blobs
bounder more and higher than larger fatter blobber blobs?

not sure i am 100% keen on the way the blobs stretch out, but maybe thats
just me..


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Nice, but is a bit unnatural.  The viscosity seems more like honey, but
the flowing behaviour not, honey would flow in lines and not form single
droplets.  Of course that's a matter of inter partcle forces.  

It would be nice to see a version, where a lot of additional particles are
added at the between position, something like a still combining all the
particles of all animation steps.

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

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"Rick [Kitty5]" wrote:
> looking much better, although i would still say it neads many
> many more smaller blobs :)

That will be later! :)

> very impressive how you have managed to get it perfectly cyclic.

Thanks! It was quite a headache to implement, but it seems to work now.

> does a blobs behavour change acording to its size?

No.

> - ie smaller blobs bounder more and higher than larger fatter
> blobber blobs?

No, but I don't think it would be correct anyway. Theoretically if there's a
large object and a small object with the same "springiness" and the two
objects hit a surface with equal velocity, they should bounce equally much,
shouldn't they?

But anyway, I don't think a particle system can be compared to real water
that directly. Real water doesn't consist of particles. And when a water
drop hits a surface it may divide into several smaller drops and generally
behave in very complicated ways.

I hope my particle system will be cool-looking, but it's not supposed to be
used by scientists! ;)

> not sure i am 100% keen on the way the blobs stretch out, but
> maybe thats just me..

Do you mean the pseudo motion blur that stretches out the particles in the
direction of movement? I personally like it, but it can be made stronger or
weaker or turned completely off.

Rune
--
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"Bugs74" wrote:
> Good work!

Thank you! :)

> I'm really looking forward to the code...
> (This is a subtile hint.;-) )

I will release the complete particle system package eventually, but there's
still a lot of work to do before that...

Rune
--
\ Include files, tutorials, 3D images, raytracing jokes,
/ The POV Desktop Theme, and The POV-Ray Logo Contest can
\ all be found at http://rsj.mobilixnet.dk (updated January 28)
/ Also visit http://www.povrayusers.org

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> Thanks! It was quite a headache to implement, but it seems to work now.

i can well imagine!

> > does a blobs behavour change acording to its size?
>
> No.
>
> > - ie smaller blobs bounder more and higher than larger fatter
> > blobber blobs?
>
> No, but I don't think it would be correct anyway. Theoretically if there's
a
> large object and a small object with the same "springiness" and the two
> objects hit a surface with equal velocity, they should bounce equally
much,
> shouldn't they?

no, with water there is a sliding scale, large blobs are more likely to
fragment more on impact that very very small droplets witch are more likly
to either bounce almost whole, or simply stick. - this in one of the reasons
that when models are used on films for the obligatoy damn breaking scene it
dosnt look real.

> But anyway, I don't think a particle system can be compared to real water
> that directly. Real water doesn't consist of particles. And when a water
> drop hits a surface it may divide into several smaller drops and generally
> behave in very complicated ways.

i think in may ways it can be compared, and yours with thousands of
incredably small particals should be quite close (then of course we will
want you to add a detergent feature for froth & bubbles)

>
> I hope my particle system will be cool-looking, but it's not supposed to
be
> used by scientists! ;)

well, if its any consolation, one of the great unsolved problems are the
mathematical formulas for motion of fliuds like water, and turbulance in
general (hence the continuing use of wind tunnels and smoke) - skicky fluids
(like syrup) are aparently no problem, but you dont get vortex's in syrup :)

> Do you mean the pseudo motion blur that stretches out the particles in the
> direction of movement? I personally like it, but it can be made stronger
or
> weaker or turned completely off.

yes, could you add real mega pov motion blur?

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"Christoph Hormann" wrote:
> Nice, but is a bit unnatural.  The viscosity seems more
> like honey, but the flowing behaviour not

I'm aiming for water, not honey, but I know I'm not very close at this
point.
How can I make it look like the viscosity is like water?

(I know the texture should be different, but I've made it solid in these
test renders so it renders faster and so it's easier to see exactly where
the particles are.)

> It would be nice to see a version, where a lot of
> additional particles are added at the between position,
> something like a still combining all the particles of
> all animation steps.

That's just a matter of using more particles. It's a bit slow for my
computer, so I will wait with that for later...

Rune
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\ Include files, tutorials, 3D images, raytracing jokes,
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"Rick [Kitty5]" wrote:
> with water there is a sliding scale, large blobs are more
> likely to fragment more on impact

Yes, but I can't make the particles fragment!

The closest thing I can do is to use so many particles that they blob
together, so several particles look like one big one.

> very very small droplets are more likly to either bounce
> almost whole, or simply stick.

When a big water drop fragments into several smaller, do those smaller drops
bounce less than a drop that is small in the first place?

> - this in one of the reasons that when models are used on
> films for the obligatoy damn breaking scene it dosnt look real.

What models and which braking scene???

> > But anyway, I don't think a particle system can be compared
> > to real water that directly.
>
> i think in may ways it can be compared, and yours with
> thousands of incredably small particals should be quite close

Hmm, maybe.

> (then of course we will want you to add a detergent feature
> for froth & bubbles)

That might be difficult. Anyway, what do you mean by front?

> could you add real mega pov motion blur?

No, I think that's impossible since the particles are moved not by the clock
value but by an I/O system. But of course you can use regular post-rendering
motion blur...

Rune
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\ all be found at http://rsj.mobilixnet.dk (updated January 28)
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Smoooth... Nice. :) Good job, Rune! I hope you had a great time in France.
Did you see the Eiffel Tower? (You must have... :)

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