On 7-4-2016 9:17, Jaime Vives Piqueres wrote:
> El 05/04/16 a las 12:11, Jaime Vives Piqueres escribió:
>> ... still needs work.
>
>    Well, the proximity pattern is still not what I really need, but gets
> close. Unfortunately it really makes the render much slower (x4)...
> luckly I'm using a mesh: with an isosurface this would have taken almost
> 2/3 days.
>

This is very close indeed. Less convincing foam close up but in the 
distance it looks very good.

-- 
Thomas

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On 4/7/2016 8:17 AM, Jaime Vives Piqueres wrote:
> El 05/04/16 a las 12:11, Jaime Vives Piqueres escribió:
>> ... still needs work.
>
>    Well, the proximity pattern is still not what I really need, but gets
> close. Unfortunately it really makes the render much slower (x4)...
> luckly I'm using a mesh: with an isosurface this would have taken almost
> 2/3 days.
>

That looks good to me.
Sea state 5 or 6, I would guess.
In 2009 Edouard Poor created DF3 proximity pattern macros.
That might be worth a try.


-- 

Regards
     Stephen

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On 7-4-2016 10:08, Stephen wrote:
> On 4/7/2016 8:17 AM, Jaime Vives Piqueres wrote:
>> El 05/04/16 a las 12:11, Jaime Vives Piqueres escribió:
>>> ... still needs work.
>>
>>    Well, the proximity pattern is still not what I really need, but gets
>> close. Unfortunately it really makes the render much slower (x4)...
>> luckly I'm using a mesh: with an isosurface this would have taken almost
>> 2/3 days.
>>
>
> That looks good to me.
> Sea state 5 or 6, I would guess.
> In 2009 Edouard Poor created DF3 proximity pattern macros.
> That might be worth a try.
>
>
I was going to suggest Edouard's macros too. I prefer them to Sam's and 
believe them to be faster. Advantage is that the pattern is calculated 
and saved to file before render.

-- 
Thomas

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Am 07.04.2016 um 09:17 schrieb Jaime Vives Piqueres:
> El 05/04/16 a las 12:11, Jaime Vives Piqueres escribió:
>> ... still needs work.
> 
>   Well, the proximity pattern is still not what I really need, but gets
> close. Unfortunately it really makes the render much slower (x4)...
> luckly I'm using a mesh: with an isosurface this would have taken almost
> 2/3 days.

I'm wondering: Presuming the foam is a texture (rather than a media
effect), shouldn't a slope pattern do the job?

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El 07/04/16 a las 09:58, Thomas de Groot escribió:
> This is very close indeed. Less convincing foam close up but in the
> distance it looks very good.

   That's another matter... the foam texture is not very good. I find it
very difficult to get a convincing one.

--
jaime

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El 07/04/16 a las 10:08, Stephen escribió:
> That looks good to me. Sea state 5 or 6, I would guess.

   Thanks!

> In 2009 Edouard Poor created DF3 proximity pattern macros. That might
> be worth a try.

   Thanks, I will try... also the proximity pattern included on hgpovray
(I just found about it).

--
jaime

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El 07/04/16 a las 13:35, clipka escribió:
> I'm wondering: Presuming the foam is a texture (rather than a media
> effect), shouldn't a slope pattern do the job?
>

   Yes, it is a texture (well, a pattern for the combined water/foam
texture map). And yes, that's what I thought at first, so I tried a
slope y with altitude, but didn't work very well... maybe my fault at
implementing it, but then I thought about the proximity pattern thing,
so I abandoned the slope approach.

--
jaime

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Am 07.04.2016 um 13:47 schrieb Jaime Vives Piqueres:
> El 07/04/16 a las 13:35, clipka escribió:
>> I'm wondering: Presuming the foam is a texture (rather than a media
>> effect), shouldn't a slope pattern do the job?
>>
> 
>   Yes, it is a texture (well, a pattern for the combined water/foam
> texture map). And yes, that's what I thought at first, so I tried a
> slope y with altitude, but didn't work very well... maybe my fault at
> implementing it, but then I thought about the proximity pattern thing,
> so I abandoned the slope approach.

I wouldn't use altitude, just the plain slope.

Given that the slope pattern is a lot faster than any proximity pattern,
I think it should be worth another try.

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El 07/04/16 a las 15:52, clipka escribió:
> I wouldn't use altitude, just the plain slope.
>
> Given that the slope pattern is a lot faster than any proximity
> pattern, I think it should be worth another try.
>

   But just plain "slope y" shows foam also on "valley" parts of the
surface, not only on the crests. Or are you suggestion another approach?

--
jaime

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Am 07.04.2016 um 16:26 schrieb Jaime Vives Piqueres:
> El 07/04/16 a las 15:52, clipka escribió:
>> I wouldn't use altitude, just the plain slope.
>>
>> Given that the slope pattern is a lot faster than any proximity
>> pattern, I think it should be worth another try.
>>
> 
>   But just plain "slope y" shows foam also on "valley" parts of the
> surface, not only on the crests. Or are you suggestion another approach?

From what I see the waves aren't sinusoidal, but have "sharp" peaks, so
a high slope should be the proper indicator.

Then again, I must concede that this idea crumbles if the peaks aren't
perfectly sharp after all.


Let's take a step backward:

What you want is foam at the crests, i.e. near local maxima.

Local maxima can be identified by a zero 1st derivative (aka slope) and
negative 2nd derivative (aka curvature).

It should be possible to analyze the f_ridged_mf() function in order to
construct the 1st and 2nd derivative functions, and use the resulting
functions as a basis for a foam pattern. (If you want to avoid function
analysis, you could still design functions for the slope and curvature
that effectively take samples from the original function.)

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