Bob Hughes wrote:
> 
> Btw, I tried this with version 3.02.watcom.win32, 3.1g.watcom.win32, and also
> MegaPov 0.4.  Only MegaPov will render correctly when 'transmit' is used,
> 'filter' works okay in all 3 versions.  I thought maybe it might be
> 'max_trace_level' dependant but it doesn't help if it's increased to 50 instead
> of leaving at default 5.  So something got fixed in Nathan's patched pov.

Nathan changed the way that layered filtered textures behave in MegaPov
- been public knowlege for some time now.

-- 
Ken Tyler -  1300+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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Bob Hughes wrote:
> 
> Yep, I just realized it was actually there too, not blacked out and gone
> entirely, just very dark.  I turned up the color of the light source to 10.
> Something's wrong in the official versions though, I just couldn't say not
> knowing anything about the source code workings.  Maybe Nathan has an idea.
> At the beginning I simply thought the problem might be the layering over a
> layered texture, which I expected would make an error show up.  Maybe that's
> still something to do with it though.

In the official version layered textures that use filter or transmit
react the same i.e. they both default to the behavior of filter. In
MegaPov Nathan changed this so that transmit works "correctly" or so
he claims. It's not really a bug as much as it is a dissagreement as
to what the correct behavior should be where layered textures are
concerned. I do not know at this point if this change will be reflected
in POV-Ray v3. or not. It will definately break a lot of pre v3.5
textures if it is implememnted though the #version directive can be
used to compensate for this.

-- 
Ken Tyler -  1300+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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In article <38B93A53.83D12556@pacbell.net>, lin### [at] povrayorg 
wrote:

> In the official version layered textures that use filter or transmit
> react the same i.e. they both default to the behavior of filter. In
> MegaPov Nathan changed this so that transmit works "correctly" or so
> he claims. It's not really a bug as much as it is a dissagreement as
> to what the correct behavior should be where layered textures are
> concerned. I do not know at this point if this change will be reflected
> in POV-Ray v3. or not. It will definately break a lot of pre v3.5
> textures if it is implememnted though the #version directive can be
> used to compensate for this.

Actually, it is filter that acts like transmit in layered textures in 
the official version. MegaPOV fixes it so filter acts like filter and 
transmit like transmit(makes more sense, doesn't it?). Since it is 
documented in the manual, it can't really be considered a bug, so I call 
it a "documented mis-feature". :-)

And converting older textures is actually quite easy: just set the 
filter in the upper layers to 0 and add the value that was there to the 
transmit value. This should give the same appearance as it had in the 
official version. Or you could use the #version directive...

-- 
Chris Huff
e-mail: chr### [at] yahoocom
Web page: http://chrishuff.dhs.org/

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No, that can't be the reasoning for the darkness increase.  Something else must
be going on.  I'd have expected a problem with filter and because I knew about
Nathan's changes I wouldn't have thought transmit would be the thing that is
different from the official versions.  Even if you were to consider transmit and
filter behaviour to be switched in the official versions (bear with me please, I
know it isn't) to explain why the darkening occurs I'd still think filtering
should not be such a tremendous change just because one more layer is added.
Seems to be related to layering onto a layered texture that's doing it.
I tested this ought again and if a layers of image maps is declared first then
put in as the base layer of the plane texturing then it's fine, no problems.
However if layering of the usual pigments (pattern, no pattern) is declared and
added in as the base texture to the plane then it breaks down.
Something must be wrong (or never meant to be) in official then, but check for
yourselves.  Here's what I was doing:

// #version 3.1;
// unofficial MegaPov 0.4;

global_settings {
        max_trace_level 5
}

#include "colors.inc"
#include "stones.inc"

light_source { 10*y color rgb 1}
camera {
  location  <0,9,9>
  angle 67
  look_at   0
}

#declare Layer1=
        texture { // base
                pigment {rgb <1,1,1>
                      //  image_map {gif "test.gif" transmit 0, 1}
        // translate -.5 scale 6 rotate 90*x
         }
                }
        texture {
                pigment {rgbf <0,1,0,1>
                     //   image_map {gif "test.gif" transmit 0, 1}
        // translate 0 scale 6 rotate 90*x rotate 90*y
        }
                }

plane {y,0
        texture {Layer1 // using this instead of the Stone17 texture
        //        pigment {image_map {gif "test.gif" transmit 0, 1}
       // translate 0 scale 6 rotate 90*x rotate 90*y}
                // T_Stone17
                }
        texture {
                pigment {image_map {gif "test.gif" transmit 0, 1}
         translate -.5 scale 6 rotate 90*x}
                }
}


Bob

"Chris Huff" <chr### [at] yahoocom> wrote in message
news:chrishuff_99-6D5671.10202927022000@news.povray.org...
| In article <38B93A53.83D12556@pacbell.net>, lin### [at] povrayorg
| wrote:
|
| > In the official version layered textures that use filter or transmit
| > react the same i.e. they both default to the behavior of filter. In
| > MegaPov Nathan changed this so that transmit works "correctly" or so
| > he claims. It's not really a bug as much as it is a dissagreement as
| > to what the correct behavior should be where layered textures are
| > concerned. I do not know at this point if this change will be reflected
| > in POV-Ray v3. or not. It will definately break a lot of pre v3.5
| > textures if it is implememnted though the #version directive can be
| > used to compensate for this.
|
| Actually, it is filter that acts like transmit in layered textures in
| the official version. MegaPOV fixes it so filter acts like filter and
| transmit like transmit(makes more sense, doesn't it?). Since it is
| documented in the manual, it can't really be considered a bug, so I call
| it a "documented mis-feature". :-)
|
| And converting older textures is actually quite easy: just set the
| filter in the upper layers to 0 and add the value that was there to the
| transmit value. This should give the same appearance as it had in the
| official version. Or you could use the #version directive...
|
| --
| Chris Huff
| e-mail: chr### [at] yahoocom
| Web page: http://chrishuff.dhs.org/

Post a reply to this message