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Hi again!
I found a way to allow grains of different sizes to placed, and the results
aren't so bad! All I needed to do was to subtract blob components with sizes
*relative* to the grain being produced. To do /that/, however, required an extra
loop in which all neighboring point distances were added up and averaged to
determine an acceptable size for the current grain.
Voronoi calculation time for scene: about 3 seconds. Parse time: 3 seconds.
Render time with one 12x12 area-illuminating area light: 10 minutes 6 seconds.
Not too bad!
The biggest problem I can see is that some grains (other than those assumed to
be held up by walls) appear to float. These are so few, and the parsing time so
short, that for a final scene grains could be placed manually to make it look
physically-correct.
I'd love to make this available to everyone, but I don't know where to start :(
I could just drop some source/binaries and hope for the best...
Sam
 
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Download '2296-grains.jpg' (100 KB)
 
  
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In sedimentological terms, this would be an inversely graded set consisting 
of moderately sorted, moderately to badly rounded, medium to very coarse 
sand with cobble-sized elements... Oh well, don't make me repeat myself too 
often, please ;-)
Thomas
 
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On 4/3/2011 12:59 AM, Thomas de Groot wrote:
> In sedimentological terms, this would be an inversely graded set consisting
> of moderately sorted, moderately to badly rounded, medium to very coarse
> sand with cobble-sized elements... Oh well, don't make me repeat myself too
> often, please ;-)
Your, ahem, expertise in this field is appreciated ;P
 
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Continuing in the same vein...
I was over-complicating each blob's influence, and it was causing the 
smaller particles to become too spaced.
Here's a set of over 27,000 particles. Variable particle density was 
used to give the appearance of strata. Parse time was around 30 seconds, 
render time was 6 minutes, 18 seconds.
This will be it for while, at least until I can take it to the next 
level. Hopefully I'll get this working with spherical objects, at which 
point things like gumball machines and granular flow will become 
possible (realistic avalanches might even become a possibility).
If nothing else, it's a highly entertaining way to spend my time :)
Sam
 
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Attachments: 
Download '27841-grains.jpg' (115 KB)
 
  
Preview of image '27841-grains.jpg'
   
   
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"stbenge" <"egnebts <-inverted"@hotmail.com> schreef in bericht 
news:4d98c261$1@news.povray.org...
> Your, ahem, expertise in this field is appreciated ;P
Whatever it is worth in the POV-Ray world... ;-)
Thomas
 
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Better and better!
You know, Sam, this is very like RL. I just cannot help myself to see a 
river bed here. I hope you will develop further along these lines. Great 
work, as usual.
Thomas
 
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This looks awesome, and the technique is very elegant! I look forward to further
developments.
I think it could be adapted to make excellent drystone walls.
Bill
 
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>Samuel Benge  on date 03/04/2011 02:09 wrote:
> Hi again!
>
> I found a way to allow grains of different sizes to placed, and the results
> aren't so bad! All I needed to do was to subtract blob components with sizes
> *relative* to the grain being produced. To do /that/, however, required an extra
> loop in which all neighboring point distances were added up and averaged to
> determine an acceptable size for the current grain.
>
> Voronoi calculation time for scene: about 3 seconds. Parse time: 3 seconds.
> Render time with one 12x12 area-illuminating area light: 10 minutes 6 seconds.
> Not too bad!
>
> The biggest problem I can see is that some grains (other than those assumed to
> be held up by walls) appear to float. These are so few, and the parsing time so
> short, that for a final scene grains could be placed manually to make it look
> physically-correct.
>
> I'd love to make this available to everyone, but I don't know where to start :(
> I could just drop some source/binaries and hope for the best...
>
> Sam
I like e lot the colors of these grains.
;-)
Paolo
 
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so very awesome.  We can always say the floating particles were actually 
caught midair from a fall.
-- 
a game sig: http://tinyurl.com/d3rxz9
 
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Very impressive!
So, if these are blobs the roughness is just texture?
Reading up a bit on Voronoi diagrams I found this
entertaining interactive web application:
http://www.pi6.fernuni-hagen.de/GeomLab/VoroGlide/
 
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