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From: Rafal 'Raf256' Maj
Subject: Re: Big whopping sparks
Date: 15 May 2004 23:33:09
Message: <Xns94EB384D96A5Braf256com@203.29.75.35>
dva### [at] cedarnet news:40a6e00d@news.povray.org

> What sort of options are available for making big whopping sparks that
> light up the scene?

FOr questions please use povray.general (or .newusers).

As for sparks, You can use 
1) small bat very bright emission media
2) small spheres/etc with high ambient finish
3) real light sources

options 1) and 2) need radiosity and therefore are usualy slow, on the 
other hand using 3) is slow when YOu have too meany sparks.

Btw funny I was qoing to write a small FAQ/tutorial about it I hope You 
will find it usefull :)

-- 
http://www.raf256.com/3d/
Rafal Maj 'Raf256', home page - http://www.raf256.com/me/
Computer Graphics


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From: Dave VanHorn
Subject: Re: Big whopping sparks
Date: 16 May 2004 00:01:21
Message: <40a6e791$1@news.povray.org>
"Rafal 'Raf256' Maj" <spa### [at] raf256com> wrote in message
news:Xns94EB384D96A5Braf256com@203.29.75.35...
> dva### [at] cedarnet news:40a6e00d@news.povray.org
>
> > What sort of options are available for making big whopping sparks that
> > light up the scene?
>
> FOr questions please use povray.general (or .newusers).

ALrighty then.. :)

> As for sparks, You can use
> 1) small bat very bright emission media
> 2) small spheres/etc with high ambient finish
> 3) real light sources

> options 1) and 2) need radiosity and therefore are usualy slow, on the
> other hand using 3) is slow when YOu have too meany sparks.

Well, 38 smallish sparks, and one big whopping one.

> Btw funny I was qoing to write a small FAQ/tutorial about it I hope You
> will find it usefull :)

Cool.


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From: Alain
Subject: Re: Big whopping sparks
Date: 16 May 2004 08:43:15
Message: <40a761e3$1@news.povray.org>
Dave VanHorn nous apporta ses lumieres ainsi en ce 2004/05/16 00:02... :

>"Rafal 'Raf256' Maj" <spa### [at] raf256com> wrote in message
>news:Xns94EB384D96A5Braf256com@203.29.75.35...
>  
>
>>dva### [at] cedarnet news:40a6e00d@news.povray.org
>>
>>    
>>
>>>What sort of options are available for making big whopping sparks that
>>>light up the scene?
>>>      
>>>
>>FOr questions please use povray.general (or .newusers).
>>    
>>
>
>ALrighty then.. :)
>
>  
>
>>As for sparks, You can use
>>1) small but very bright emission media
>>2) small spheres/etc with high ambient finish
>>3) real light sources
>>    
>>
>
>  
>
>>options 1) and 2) need radiosity and therefore are usualy slow, on the
>>other hand using 3) is slow when YOu have too meany sparks.
>>    
>>
>
>Well, 38 smallish sparks, and one big whopping one.
>
>  
>
>>Btw funny I was qoing to write a small FAQ/tutorial about it I hope You
>>will find it usefull :)
>>    
>>
>
>Cool.
>
>
>  
>
With that kind of count, I'd go for solutions 1 and/or 2, could give you 
better results in less time.

Alain


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From: Dave VanHorn
Subject: Re: Big whopping sparks
Date: 16 May 2004 09:42:38
Message: <40a76fce$1@news.povray.org>
> With that kind of count, I'd go for solutions 1 and/or 2, could give you
> better results in less time.
>
> Alain

Ok, #1 sounds good, but how do you actually generate something that looks
spark-like?

I found an include file for Megapov, but I'd rather stick with Pov-ray.


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From: Alain
Subject: Re: Big whopping sparks
Date: 16 May 2004 10:24:11
Message: <40a7798b$1@news.povray.org>
Dave VanHorn nous apporta ses lumieres ainsi en ce 2004/05/16 09:43... :

>>With that kind of count, I'd go for solutions 1 and/or 2, could give you
>>better results in less time.
>>
>>Alain
>>    
>>
>
>Ok, #1 sounds good, but how do you actually generate something that looks
>spark-like?
>
>I found an include file for Megapov, but I'd rather stick with Pov-ray.
>
A merge of some narrow cylinders and sharp cones filed with media could 
be a starter. You may need some spheres to fill some gaps.
You can adjust the magapov include to use it with POV-Ray, it take some 
work and testing.

Alain


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From: John VanSickle
Subject: Re: Big whopping sparks
Date: 16 May 2004 12:28:09
Message: <40A79696.73CCE919@hotmail.com>
Rafal 'Raf256' Maj wrote:
> 
> dva### [at] cedarnet news:40a6e00d@news.povray.org
> 
> > What sort of options are available for making big whopping sparks that
> > light up the scene?
> 
> FOr questions please use povray.general (or .newusers).
> 
> As for sparks, You can use
> 1) small bat very bright emission media
> 2) small spheres/etc with high ambient finish
> 3) real light sources
> 
> options 1) and 2) need radiosity and therefore are usualy slow, on the
> other hand using 3) is slow when YOu have too meany sparks.
> 
> Btw funny I was qoing to write a small FAQ/tutorial about it I hope You
> will find it usefull :)

You can use small ambient=1 no_shadow objects to model the sparks, but
a light source for each spark may not always be needed; a light source
in the middle of a group of sparks may be enough to look realistic.

If the sparks are in motion, you need to model them as portions of
a tube, or use some kind of motion blur.

Regards,
John


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From: Daniel Nilsson
Subject: Re: Big whopping sparks
Date: 17 May 2004 12:30:53
Message: <40a8e8bd$1@news.povray.org>
In news:40a76fce$1@news.povray.org,
Dave VanHorn <dva### [at] cedarnet> typed:
> Ok, #1 sounds good, but how do you actually generate something that
> looks spark-like?
>
> I found an include file for Megapov, but I'd rather stick with
> Pov-ray.

I did a spark as a test once. I think it looks rather nice and it
renders quite fast too.
Furtunatly I still have the code around.

/ Daniel Nilsson

Cut here...

#include "colors.inc"
#include "metals.inc"

camera {
  location <5, 4, -10>
  look_at <0, -4, 0>
}

light_source { <0, 0, 0> rgb <0.1, 0.4, 1.0>
  area_light x*5.9, z*0.3, 5, 3
  adaptive 1
  fade_distance 4
  fade_power 2
}

sphere { <-4, 0, 0>, 1 texture { T_Chrome_2E } }
sphere { <4, 0, 0>, 1 texture { T_Chrome_2E } }
cylinder { <-4, 0, 0>, <-4, -10, 0>, 0.1 texture { T_Chrome_2E } }
cylinder { <4, 0, 0>, <4, -10, 0>, 0.1 texture { T_Chrome_2E } }

plane { y, -10 pigment { White } }

cylinder { <-4, 0, 0>, <4, 0, 0>, 1.1
  hollow
  pigment { Clear }
  interior {
    media {
      method 3            // 3
      aa_level 3          // 4
      aa_threshold 0.05   // 0.1
      samples 16, 100     // Min 1, Max 1
      intervals 1         // 10
      ratio 0.9           // 0.9
      confidence 0.9      // 0.9
      variance 1/128      // 1/128
      jitter 0

      emission 1
      density {
        cylindrical
        rotate z*90

        color_map {
          [ 0.00 Black ]
          [ 0.40 rgb <0.1, 0.4, 1.0>*0.1 ]
          [ 0.80 rgb <0.1, 0.4, 1.0>*0.5 ]
          [ 0.90 rgb <0.1, 0.4, 1.0>*1.0 ]
          [ 1.00 rgb <0.1, 0.4, 1.0>*10 ]
        }
        warp {
          turbulence 0.5     // amount of turbulence
          octaves 4          // optional turbulence modifiers
          lambda 2
          omega 0.5
        }
      }
    }
  }
}


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From: Dave VanHorn
Subject: Re: Big whopping sparks
Date: 17 May 2004 13:46:01
Message: <40a8fa59@news.povray.org>
> I did a spark as a test once. I think it looks rather nice and it
> renders quite fast too.
> Furtunatly I still have the code around.

Looks good, now I have to see if I can get it into my scene.
Two banks of nine, plus one whopping big one.

BTW: Does this sort of spark, act as a light source?


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From: Daniel Nilsson
Subject: Re: Big whopping sparks
Date: 17 May 2004 14:47:44
Message: <40a908d0@news.povray.org>
In news:40a8fa59@news.povray.org,
Dave VanHorn <dva### [at] cedarnet> typed:
>
> Looks good, now I have to see if I can get it into my scene.
> Two banks of nine, plus one whopping big one.

It's the cylinder with its media interior that is the spark (but you've
allready figured that out, I guess), change its length and/or scale it
to make it fit your scene then translate/rotate it in place.

> BTW: Does this sort of spark, act as a light source?

The spark in my code does not light up the scene by it self unless you
use radiosity (I have not tested that with this scene). I included one
area light to approximate the light from the spark.

/ Daniel Nilsson


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From: Dave VanHorn
Subject: Re: Big whopping sparks
Date: 17 May 2004 19:12:40
Message: <40a946e8$1@news.povray.org>
> It's the cylinder with its media interior that is the spark (but you've
> allready figured that out, I guess), change its length and/or scale it
> to make it fit your scene then translate/rotate it in place.

I'm having limited success.  I've got some control over it, but not having
any luck at scaling it out to the big spark, 22 inches long (22 pov units,
or 220 pov units, or... )  Everything I do is scaled in inches, mm, or some
other real unit, so that measured parts actually fit in the scene.

> > BTW: Does this sort of spark, act as a light source?
>
> The spark in my code does not light up the scene by it self unless you
> use radiosity (I have not tested that with this scene). I included one
> area light to approximate the light from the spark.

I have radiosity turned on, but how do I make the sparks act as light
sources?


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