The water that I have going there is based on Christoph's water pages.
The transparency of the water right now uses fade_distance and fade_power,
but I might be able to do better by using a texture with gradient y and
the level of filtration controlled that way.

It would be great to be able to have cresting waves and the like,
or even something that just appears to be like that from a distance.
Could this be done with a height_field as the water?

Aaron

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-[It would be great to be able to have cresting waves and the like]-
These could be done with a height-field, so long as there was no point where
the waves were actually 'overhanging'. How to make the hightfield could be a
problem - papers do exist about this kind of thing, but from what I've read,
they have to be quite technical to give good results.

-Chris

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Chris Johnson wrote:
> -[It would be great to be able to have cresting waves and the like]-
> These could be done with a height-field, so long as there was no
> point where the waves were actually 'overhanging'. How to make the
> hightfield could be a problem - papers do exist about this kind of
> thing, but from what I've read, they have to be quite technical to
> give good results.

Maybe Tim Nikias' Liquid-Surface-Simulation-Macros could be used?

I'm not sure, but it'd be worth a try.

http://www.digitaltwilight.de/no_lights/download.html

Rune
--
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com **updated Jul 25**
POV-Ray Ring: http://webring.povray.co.uk

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Thanks for the Heads Up!

I'm not quiet sure what Aaron is after here. The LSSM
would probably be suited to create some waves
surrounding the islands (using the LSS_Stomp macro)
and waves reflecting off of the island's coasts (with
proper setting for LSS_Environment, though I guess
"inside"-test works fine with heightfields), but
if he's after waves rising in height and crashing onto
the shores (which occurs when waves travel towards
and on top of less and less deeper areas), thats
not possible...

Might still be worth a try though. The waves dissipate
over distance (as you well know, Rune :-), so for a
still, LSS_Stomp could be used to issue some waves
from the coasts, they'll get softer outwards...

Regards,
Tim

-- 
Tim Nikias v2.0
Homepage: http://www.digitaltwilight.de/no_lights

"Rune" wrote:

> Chris Johnson wrote:
> > -[It would be great to be able to have cresting waves and the like]-
> > These could be done with a height-field, so long as there was no
> > point where the waves were actually 'overhanging'. How to make the
> > hightfield could be a problem - papers do exist about this kind of
> > thing, but from what I've read, they have to be quite technical to
> > give good results.
>
> Maybe Tim Nikias' Liquid-Surface-Simulation-Macros could be used?
>
> I'm not sure, but it'd be worth a try.
>
> http://www.digitaltwilight.de/no_lights/download.html
>
> Rune
> --
> 3D images and anims, include files, tutorials and more:
> rune|vision:  http://runevision.com **updated Jul 25**
> POV-Ray Ring: http://webring.povray.co.uk
>
>


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Tim, Rune:

Thanks ... this is basically what I am looking for.

I might be able to make some crests on the waves by fiddling
around with pigments and normals.

> Might still be worth a try though. The waves dissipate
> over distance (as you well know, Rune :-), so for a
> still, LSS_Stomp could be used to issue some waves
> from the coasts, they'll get softer outwards...

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-[I might be able to make some crests on the waves by fiddling around with
pigments and normals]-
By crests, do you mean white peaks of bubbles at the top of waves? If so,
you ought to be able to find out where these are on a heightfield by looking
for peaks in the heightfield, i.e. where the gradient is (close to) zero and
where the curvature is negative. These can be found by comparing each point
in the heightfield with its 4 closest neighbours (those points north, south,
east and west of it):

Gradient is close to zero when the difference in height between the north
and south points is small, and the difference in height between east and
west points is small.

Curvature is negative when the height of the point in question is greater
than the average heights of the four points around it.

When both of these conditions are satisfied, the point in the centre is on
the crest of a wave, and the texture could be modified accordingly.

I'm not sure how easy it would be to incorporate this into the Tim's LSSM
macros - I don't remember having seen macro-generated pigments/textures
before, so it may not be possible without an external program to generate
image files for colour maps.

-Chris

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Yeah, yeah.. I kind of asked for that, didn't I? hehehe

Nice pic :)

/Stefan

"Aaron Gillies" <no### [at] nospamcom> wrote in message
news:3f4c2b1b$1@news.povray.org...
> Oh ... and for Stephan from Klippan ... it is a compressed JPEG.
>
> Aaron
>
>

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No prob, Aron..  ;)

/Stefan

"Aaron Gillies" <no### [at] nospamcom> wrote in message
news:3f4c37b0@news.povray.org...
> Here is one with slightly improved foliage.  And I realized that I
> misspelled Stefan in the previous post.
>
>
>

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-[if he's after waves rising in height and crashing onto the shores...,
thats not possible]-
Just being a pedant here :)
This sort of thing _has_ been simulated before (though clearly not with a
heightfield, if thats what you meant), but its fairly complex stuff... There
are some fairly modern algorithms which cope with a completely arbitrary
water/air interface surface, so things like splashes and drips can be done
with the same algorithms as waves on large bodies of water.

http://graphics.stanford.edu/~fedkiw/papers/stanford2001-02.pdf
http://www.cis.upenn.edu/~fostern/pdfs/gmip96.pdf

This paper:
http://graphics.stanford.edu/papers/water-sg02/water.pdf

deals specifically with the problem in this image - realistic breaking waves
on a beach, among other things. When I see things like the attached image in
a paper on computer grapics, I wonder why I bother with my own crude little
Pov-Ray macros :)

-Chris

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Attachments:
Download 'water.jpg' (19 KB)

Preview of image 'water.jpg'

> -[if he's after waves rising in height and crashing onto the shores...,
> thats not possible]-
> Just being a pedant here :)
 SNIP

Yeah, what I meant is that it is not sufficiently possible
with just heightfields, and surely not possible with my
LSSM. The Paper you're referring to is quiet complex
and would probably be too slow for POV-SDL to
actually attempt to script it. Though I don't know if
someone might have attempted an "outside" implementation
in C++.

Regards,
Tim

-- 
Tim Nikias v2.0
Homepage: http://www.digitaltwilight.de/no_lights


> -[if he's after waves rising in height and crashing onto the shores...,
> thats not possible]-
> Just being a pedant here :)
> This sort of thing _has_ been simulated before (though clearly not with a
> heightfield, if thats what you meant), but its fairly complex stuff...
There
> are some fairly modern algorithms which cope with a completely arbitrary
> water/air interface surface, so things like splashes and drips can be done
> with the same algorithms as waves on large bodies of water.
>
> http://graphics.stanford.edu/~fedkiw/papers/stanford2001-02.pdf
> http://www.cis.upenn.edu/~fostern/pdfs/gmip96.pdf
>
> This paper:
> http://graphics.stanford.edu/papers/water-sg02/water.pdf
>
> deals specifically with the problem in this image - realistic breaking
waves
> on a beach, among other things. When I see things like the attached image
in
> a paper on computer grapics, I wonder why I bother with my own crude
little
> Pov-Ray macros :)
>
> -Chris
>
>
>


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