POV-Ray : Newsgroups : povray.advanced-users : Transparency controlled by the angle of the light beam Server Time
24 Nov 2024 19:40:23 EST (-0500)
  Transparency controlled by the angle of the light beam (Message 1 to 7 of 7)  
From: Henrik Fisch
Subject: Transparency controlled by the angle of the light beam
Date: 30 Mar 2005 08:35:01
Message: <web.424aaaccbb332d515443a1c10@news.povray.org>
I need this feature for simulating stretched materials like an inflated toy
balloon. Normally you can look through the balloon. As your sight goes near
the walls of the balloon, you will notice that the balloon is no longer
transparent but will become more and more opaque. This feature is present
for example in Poser (e.g. V 4.03), whre you can set a min and a max value
for the transparency. But I can not find it in POVRay.

Please help. Do I miss anything in the documentation or is it not possible
to do something like that?

Regards,
Henrik Fisch


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From: ingo
Subject: Re: Transparency controlled by the angle of the light beam
Date: 30 Mar 2005 10:43:34
Message: <Xns9629B451F3392seed7@news.povray.org>
in news:web.424aaaccbb332d515443a1c10@news.povray.org Henrik Fisch
wrote: 

> This feature is present
> for example in Poser (e.g. V 4.03), whre you can set a min and a max
> value for the transparency. But I can not find it in POVRay.
> 

Instead of giving the balloon just a colour, try the "wall" of the balloon 
a scattering media. Althogh I didn't ry I have the feeling it will give 
the result you're looking for.

Ingo


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From: Henrik Fisch
Subject: Re: Transparency controlled by the angle of the light beam
Date: 30 Mar 2005 12:45:01
Message: <web.424ae58ea3b6bbc9218d447c0@news.povray.org>
ingo <ing### [at] tagpovrayorg> wrote:
> Instead of giving the balloon just a colour, try the "wall" of the balloon
> a scattering media. Althogh I didn't ry I have the feeling it will give
> the result you're looking for.
>
> Ingo

Thank you, Ingo!

I will try this.

Regards,
Henrik


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From: Sascha Ledinsky
Subject: Re: Transparency controlled by the angle of the light beam
Date: 30 Mar 2005 14:03:07
Message: <424af7eb$1@news.povray.org>
Take a look at MegaPov - http://megapov.inetart.net/

You could use its AOI (angle-of-incidence) pattern and a texture map to 
create the effect you described.

Regards,
-Sascha Ledinsky

Henrik Fisch wrote:
> I need this feature for simulating stretched materials like an inflated toy
> balloon. Normally you can look through the balloon. As your sight goes near
> the walls of the balloon, you will notice that the balloon is no longer
> transparent but will become more and more opaque. This feature is present
> for example in Poser (e.g. V 4.03), whre you can set a min and a max value
> for the transparency. But I can not find it in POVRay.
> 
> Please help. Do I miss anything in the documentation or is it not possible
> to do something like that?
> 
> Regards,
> Henrik Fisch
> 
>


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From: Alain
Subject: Re: Transparency controlled by the angle of the light beam
Date: 30 Mar 2005 19:05:44
Message: <424b3ed8$1@news.povray.org>
Henrik Fisch nous apporta ses lumieres en ce 2005-03-30 08:34:
> I need this feature for simulating stretched materials like an inflated toy
> balloon. Normally you can look through the balloon. As your sight goes near
> the walls of the balloon, you will notice that the balloon is no longer
> transparent but will become more and more opaque. This feature is present
> for example in Poser (e.g. V 4.03), whre you can set a min and a max value
> for the transparency. But I can not find it in POVRay.
> 
> Please help. Do I miss anything in the documentation or is it not possible
> to do something like that?
> 
> Regards,
> Henrik Fisch
> 
> 
Another possible way: Make the baloon rgbt 1, give it some thickness and give it a
fade_calor of the 
couour you want and fade_distance <some prety small value>
That way, when you see it perpendicular, it's almost transparent, but when viewed a
low angle, the 
thickness becomes significant and the colour very visible. It should be faster than
using media.

Alain


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From: Henrik Fisch
Subject: Re: Transparency controlled by the angle of the light beam
Date: 31 Mar 2005 06:00:00
Message: <web.424bd700a3b6bbc95443a1c10@news.povray.org>
Hello Sascha,

whow, the "Angle of incidence" in MegaPOV is exactly what I need! Thank you!
:)

What I still not understand is, why the program calculates this angle to a
value grerater than 0.5 only if there are reflections or refractions. It
would be useful if this parameter is always available in it's full range.
But anyway, I think I can come around with this if I set the reflection to
a very low level.

Regards,
Henrik Fisch

Sascha Ledinsky <sas### [at] userssourceforgenet> wrote:
> Take a look at MegaPov - http://megapov.inetart.net/
>
> You could use its AOI (angle-of-incidence) pattern and a texture map to
> create the effect you described.
>
> Regards,
> -Sascha Ledinsky


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From: Rune
Subject: Re: Transparency controlled by the angle of the light beam
Date: 31 Mar 2005 09:59:06
Message: <424c103a@news.povray.org>
Henrik Fisch wrote:
> whow, the "Angle of incidence" in MegaPOV is exactly what I need!
> Thank you! :)
>
> What I still not understand is, why the program calculates this angle
> to a value grerater than 0.5 only if there are reflections or
> refractions. It would be useful if this parameter is always available
> in it's full range. But anyway, I think I can come around with this
> if I set the reflection to a very low level.

No, the point is (I think) that only rays that hits the surface from the 
inside can generate angles larger than 90 degrees (from the normal) and thus 
values above 0.5. This often happen if you have refraction, but it can also 
happen in other cases, so I'm not sure why it's phrased in terms of 
reflection and refraction in the documentation.

Anyway, I'm not sure why it's important to you that the full range is 
available. You can just define your color_map (or pigment_map or whatever) 
from 0.0 to 0.5 instead of from 0.0 to 1.0.

Best regards,

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


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