POV-Ray : Newsgroups : povray.beta-test : Severe Lightbug, probably concerned with Macros... (long post) Server Time
4 Jul 2022 08:22:11 EDT (-0400)
  Severe Lightbug, probably concerned with Macros... (long post) (Message 1 to 4 of 4)  
From: Tim Nikias
Subject: Severe Lightbug, probably concerned with Macros... (long post)
Date: 20 Jan 2002 07:58:48
Message: <3C4ABED3.F038E200@gmx.de>
Hi there!

The code for the image was written in POV-Ray 3.1g and the image traced
as
expected. Now, with POV-Ray 3.5 Beta 10, running on a 1.4 GHZ Athlon
with
512 MB Ram on Windows 98, it does not.
I have not found any similiar bug in the bug-list, and I think this is a
new one.
I'll see if the bug also takes place in the Beta 9, to see if it has to
do with some
changes.

The image at the end shows the problem: the lighting is messed up,
though the light-
source is positioned just above the center of the chessboard. Figurines
are placed
with macros, as is the board.

Here a more detailed description:

The setup is easy:
One include file with several measurement-macros (like #macro mm(Val)
(.01*Val) #end)
One include file with several object-macros.
The way these work is simple: call the macro with some parameters like
position, color
etc, and then, unions of objects are placed using the macro, like:
#macro Place_Obj(Position,Scale,Rotation,Color)
 union{ [..] //Some objects like spheres, cylinders etc
 pigment{rgb Color}
 scale Scale
 rotate Rotation
 translate Position
}
#end

The bug is as follows:
After including the files with the macros, and then placing them, the
shadows and illumination
aren't properly. The lightsource (the only one, I checked several times
using "search" for "light")
is positioned right in the middle of the chessboard, a few centimeters
up.
As you can see in the attached image, some objects are illuminated from
below, the sides or
whereever!

I don't know if this has to do with the macros (though they don't look
wrong or too complicated
to be misunderstood that easily), or the light-sources, or something of
both.

Now, I will post the scene-file with a more detailed description in the
binaries.

--
Tim Nikias
Homepage: http://www.digitaltwilight.de/no_lights/index.html


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Attachments:
Download 'chs_test.jpg' (19 KB)

Preview of image 'chs_test.jpg'
chs_test.jpg


 

From: Warp
Subject: Re: Severe Lightbug, probably concerned with Macros... (long post)
Date: 20 Jan 2002 08:26:36
Message: <3c4ac58c@news.povray.org>
Binary attachments should be posted to povray.beta-test.binaries, not here.

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -


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From: Tim Nikias
Subject: Re: Severe Lightbug, probably concerned with Macros... (long post)
Date: 20 Jan 2002 11:03:31
Message: <3C4AEA2B.946F245E@gmx.de>
>   Binary attachments should be posted to povray.beta-test.binaries, not here.
>

Oh, okay. I thought the image would be some help, but I understand that this is
probably
a general rule (to which it is easier to stick to, rather than make specific
exceptions all the time) ;)

Tim
--
Tim Nikias
Homepage: http://www.digitaltwilight.de/no_lights/index.html


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From: Mike Williams
Subject: Re: Severe Lightbug, probably concerned with Macros... (long post)
Date: 22 Jan 2002 04:23:17
Message: <HJJGdDAg7ST8EwQc@econym.demon.co.uk>
I confirm that there is some sort of a problem with the lighting.

I've stripped down the scene to about the minimum that reproduces the
problem, and it turns out it can be reproduced without macros. The key
factor is probably the two rotated turbulence warps in the normal. 

Change the amount of rotation in either of the "rotate"s and the
lighting changes.

Remove the second warp turbulence and the problem goes away.

Increase the height of the light_source and the effect is reduced.

The problem does not occur in POV 3.1g.



global_settings{assumed_gamma 1 ambient_light <0,0,0>}

#declare Wood =
texture{
  pigment{rgb <.95,.65,0>}
  normal{wood 
    warp{turbulence 1} rotate x*90
    warp{turbulence 1}
    }
 rotate y*220
}

light_source{<0,0.05,0> rgb 1}

camera{location <.15,.15,-.05> look_at <0,0,0>}

cylinder {0,0.05*y,0.01 
 texture {Wood}
 translate <0,0,0.09>}

plane{y*1,0 pigment{rgb y}}


-- 
Mike Williams
Gentleman of Leisure


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