Hi Folks,

I've been playing with PovMan 1.0 over the weekend and decided to write 
a shader.

I've basicly translated Philippe Debar's Skylight.inc v0.6b to a pigment 
shader. For ease of implementation I chopped out the integration to 
Jaimes Vives Piqueres' light macros and the ability to vary 'north', but 
now I have it working I'll try to reimplement these.

Attached is a test render. I'll post the .pov and .sl files in p.b.s-f 
shortly.

Please let me know what you think of it.

Bye for now,
	Mike Andrews.

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Attachments:
Download 'skytest.jpg' (18 KB)

Preview of image 'skytest.jpg'

Michael Andrews wrote:
> 
> Hi Folks,
> 
> I've been playing with PovMan 1.0 over the weekend and decided to write
> a shader.
> 
> I've basicly translated Philippe Debar's Skylight.inc v0.6b to a pigment
> shader. For ease of implementation I chopped out the integration to
> Jaimes Vives Piqueres' light macros and the ability to vary 'north', but
> now I have it working I'll try to reimplement these.

Nice idea but i am not sure if this would be the most efficient way. 
POV-Man shaders are not extremely fast.  Even using native POV-Ray 3.5
functions would be quite a bit faster probably.  

Concerning the image - the brightness ratio between sky near and far away
from the sun does not seem right, the sky directly at the sun is darker
than the brightest parts of the ground.

Christoph

-- 
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 28 Feb. 2003 _____./\/^>_*_<^\/\.______

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Michael Andrews wrote:
> Hi Folks,
> 
> Please let me know what you think of it.
> 
Is there any noticeable speed difference between Debar's macros and 
shader? I guess that this picture renders fast enough, so this speed 
difference is probably insignificant for such pictures...
Can't say anything about the picture itself, as I'm not familiar with 
Debar's macros or original paper...

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3ed3869c$1@news.povray.org...
> Is there any noticeable speed difference between Debar's macros and
> shader? I guess that this picture renders fast enough, so this speed
> difference is probably insignificant for such pictures...

IIRC, Philippe Debar's macro works by creating a faceted sphere and
assigning a different texture to each facet, and both operations are quite
slow (it's like building a giant bitmap pixel per pixel).

G.

--

**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters

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Gilles Tran wrote:
> 
> IIRC, Philippe Debar's macro works by creating a faceted sphere and
> assigning a different texture to each facet, and both operations are quite
> slow (it's like building a giant bitmap pixel per pixel).

But it will render fairly fast which is the most important thing (a
sky_sphere with a image_map pigment could be even faster but this will
have problems with limited dynamic range with current POV-Ray of course).

Christoph

-- 
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 28 Feb. 2003 _____./\/^>_*_<^\/\.______

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Christoph Hormann wrote:
> 
> Gilles Tran wrote:
> 
>>IIRC, Philippe Debar's macro works by creating a faceted sphere and
>>assigning a different texture to each facet, and both operations are quite
>>slow (it's like building a giant bitmap pixel per pixel).
> 
> 
> But it will render fairly fast which is the most important thing (a
> sky_sphere with a image_map pigment could be even faster but this will
> have problems with limited dynamic range with current POV-Ray of course).


Yes, I still have to add a save mesh feature - among many other things. 
Just waiting for RL to slow a little to do that...


Povingly,


Philippe

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