POV-Ray : Newsgroups : povray.unofficial.patches : Photon Patch Bug Report Server Time
3 Sep 2024 02:14:02 EDT (-0400)
  Photon Patch Bug Report (Message 1 to 7 of 7)  
From: Ken
Subject: Photon Patch Bug Report
Date: 5 Apr 1999 19:20:51
Message: <3709361B.D5A08BEE@pacbell.net>
Ken calls to Nathan in a quite and apologetic voice,

 The Photon patch seems to be mishandling layered textures.

Render the attached example in the official version to see
how it is supposed to behave then render it in the Photon
patch version. There is a marked and notable difference in
output between the two. Note that there is no use of any of
the special features of the patch and the scene is set up
for compatibility with most any version of pov after 3.0x.
With minor changes it would render in Pov v2.2 where the
texture in question was originaly designed and used.

-- 
Ken Tyler

mailto://tylereng@pacbell.net


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Attachments:
Download 'fotonbug.pov.txt' (2 KB)

From: Nathan Kopp
Subject: Re: Photon Patch Bug Report
Date: 5 Apr 1999 23:37:02
Message: <3709729A.86654063@Kopp.com>
Ok... this one is my fault... I changed the layer-texture code (to something
that I thought would work correctly... looks like I was wrong).  I was
trying to fix the "one-layer-has-transmit-and-the-other-has-filter-and-my-
texture-is-black" bug.  Sorry about that.  When I merge photons with the
superpatch (this weekend, probably), you'll have your old layered textures
back.  The photon mapping stuff is part of my "highly-experimental" personal
compile right now...

-Nathan

Ken wrote:
> 
> Ken calls to Nathan in a quite and apologetic voice,
> 
>  The Photon patch seems to be mishandling layered textures.
> 
> Render the attached example in the official version to see
> how it is supposed to behave then render it in the Photon
> patch version. There is a marked and notable difference in
> output between the two. Note that there is no use of any of
> the special features of the patch and the scene is set up
> for compatibility with most any version of pov after 3.0x.
> With minor changes it would render in Pov v2.2 where the
> texture in question was originaly designed and used.
> 
> --
> Ken Tyler
> 
> mailto://tylereng@pacbell.net
> 
>   -------------------------------------------------------------------------------
> 
>                       Name: Fotonbug.pov
>    Fotonbug.pov       Type: POV-Ray scene file
(application/x-unknown-content-type-POV-Ray.Scene)
>                   Encoding: base64


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From: Ken
Subject: Re: Photon Patch Bug Report
Date: 5 Apr 1999 23:48:16
Message: <370974CA.8C6A5E7C@pacbell.net>
Nathan Kopp wrote:
> 
> Ok... this one is my fault... I changed the layer-texture code (to something
> that I thought would work correctly... looks like I was wrong).  I was
> trying to fix the "one-layer-has-transmit-and-the-other-has-filter-and-my-
> texture-is-black" bug.  Sorry about that.  When I merge photons with the
> superpatch (this weekend, probably), you'll have your old layered textures
> back.  The photon mapping stuff is part of my "highly-experimental" personal
> compile right now...
> 
> -Nathan

 I understand. I just thought you might take note that this particular
experiment had some adverse results. You mention merging with the Super
Patch. Will this include the photon mapping features as well as the rest
of the odds and ends with the experimental version ? What will you omit
with the merge if anything and are there any last minute additions ?
Any chance you will have dispersion fired up in time ?

I'm a naturally curious person and you may ignore my questions until your
ready to go public if you so wish.

-- 
Ken Tyler

mailto://tylereng@pacbell.net


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From: Nathan Kopp
Subject: Re: Photon Patch Bug Report
Date: 6 Apr 1999 00:41:12
Message: <370981A3.3189AEF5@Kopp.com>
Ken wrote:
> 
>  I understand. I just thought you might take note that this particular
> experiment had some adverse results. You mention merging with the Super
> Patch. Will this include the photon mapping features as well as the rest
> of the odds and ends with the experimental version ? What will you omit
> with the merge if anything and are there any last minute additions ?
> Any chance you will have dispersion fired up in time ?

Actually, dispersion does work now... if you specify a color_map in your
light source, the colors in the color_map will be dispersed.  I don't
have any default color maps, but I want to have some available for the
final release (whenever that is).

When I merge with the superpatch, you'll probably only get the photon
mapping stuff.  My experimental stuff will stay in my experimental
compile.

I did notice this bug earlier (in Dave Cook's ring), but I didn't
make it a priority at that time.  I just was playing with it and here's
what I did:

When you use 'filter' in the official version of POV, the layers are NOT
filtered, they are TRANSMITTED!!!  Try it... render your image, then
change all of the 'filter' keywords to 'transmit' and render again.  You'll
get the exact same texture... I just tested it in 3.1a.

The filter keyword only makes a difference for the FINAL filter for the
sum of all textures (for objects that you see through this object).

I didn't think this was such a good idea, so I changed it.  The version
of UVPov that you have still has a bug (things are too dark).  But
what I have now acts the way I (only my humble opinion, of course) think
that it SHOULD act.  Filter will filter layers below it.  So things still
look different (old scenes and all of the standard textures look
very different).

So.. when I merge with the superpatch, I won't merge this change, since it
breaks lots of scenes, but I will leave it in my experimental compile.

Comments?

-Nathan


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From: Bob Hughes
Subject: Re: Photon Patch Bug Report
Date: 7 Apr 1999 01:45:32
Message: <370AE2D1.B49F3C78@aol.com>
Sounds like another case for a switchable feature. The difference in
layered planes each with a single filtered texture and a layered texture
on one plane is very noticeable. I always thought of it in terms of a
shadowlessness between the layers of a texture versus the physically
separate ones.

Nathan Kopp wrote:
> 
> Ken wrote:
> >
> >  I understand. I just thought you might take note that this particular
> > experiment had some adverse results. You mention merging with the Super
> > Patch. Will this include the photon mapping features as well as the rest
> > of the odds and ends with the experimental version ? What will you omit
> > with the merge if anything and are there any last minute additions ?
> > Any chance you will have dispersion fired up in time ?
> 
> Actually, dispersion does work now... if you specify a color_map in your
> light source, the colors in the color_map will be dispersed.  I don't
> have any default color maps, but I want to have some available for the
> final release (whenever that is).
> 
> When I merge with the superpatch, you'll probably only get the photon
> mapping stuff.  My experimental stuff will stay in my experimental
> compile.
> 
> I did notice this bug earlier (in Dave Cook's ring), but I didn't
> make it a priority at that time.  I just was playing with it and here's
> what I did:
> 
> When you use 'filter' in the official version of POV, the layers are NOT
> filtered, they are TRANSMITTED!!!  Try it... render your image, then
> change all of the 'filter' keywords to 'transmit' and render again.  You'll
> get the exact same texture... I just tested it in 3.1a.
> 
> The filter keyword only makes a difference for the FINAL filter for the
> sum of all textures (for objects that you see through this object).
> 
> I didn't think this was such a good idea, so I changed it.  The version
> of UVPov that you have still has a bug (things are too dark).  But
> what I have now acts the way I (only my humble opinion, of course) think
> that it SHOULD act.  Filter will filter layers below it.  So things still
> look different (old scenes and all of the standard textures look
> very different).
> 
> So.. when I merge with the superpatch, I won't merge this change, since it
> breaks lots of scenes, but I will leave it in my experimental compile.
> 
> Comments?
> 
> -Nathan

-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/homepage.htm
 mailto:inv### [at] aolcom?Subject=PoV-News


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From: Michael Andrews
Subject: Re: A question about dispersion ...
Date: 8 Apr 1999 08:03:07
Message: <370C8C3C.9468334@remove-this.reading.ac.uk>
I had some fun trying out the dispersion feature over Easter - trying to
write a macro set to give a good colour spectrum for different numbers
of channels. It almost works, so I'll post it if there is any interest.

The question: can I set up a similar colour spectrum for objects? 
Say I have my light shining through a glass of coloured liquid - I'd
want to set the filter characteristics for each channel so the
refracted, dispersed spectrum would show the absorption colour of the
liquid (virtual spectroscopic analysis? ;-)

Can this sort of thing be defined?

	TIA,
		Mike Andrews.

Nathan Kopp wrote:
> Actually, dispersion does work now... if you specify a color_map in your
> light source, the colors in the color_map will be dispersed.  I don't
> have any default color maps, but I want to have some available for the
> final release (whenever that is).
[clipped]
> -Nathan


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From: Nathan Kopp
Subject: Re: A question about dispersion ...
Date: 8 Apr 1999 11:36:06
Message: <370CBE17.4B7BE870@Kopp.com>
Michael Andrews wrote:
> 
> I had some fun trying out the dispersion feature over Easter - trying to
> write a macro set to give a good colour spectrum for different numbers
> of channels. It almost works, so I'll post it if there is any interest.
> 
> The question: can I set up a similar colour spectrum for objects?
> Say I have my light shining through a glass of coloured liquid - I'd
> want to set the filter characteristics for each channel so the
> refracted, dispersed spectrum would show the absorption colour of the
> liquid (virtual spectroscopic analysis? ;-)
> 
> Can this sort of thing be defined?
> 
>         TIA,
>                 Mike Andrews.
> 
> Nathan Kopp wrote:
> > Actually, dispersion does work now... if you specify a color_map in your
> > light source, the colors in the color_map will be dispersed.  I don't
> > have any default color maps, but I want to have some available for the
> > final release (whenever that is).
> [clipped]
> > -Nathan

It can't be right now... probably in the future this will be implemented.  Does
Daren Wilson have any comments about this? (is he reading this?)

-Nathan


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