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 CAD / Ray-Tracing / 2096
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Subject: 
Re: More color problems
Newsgroups: 
lugnet.cad.ray
Date: 
Fri, 6 Feb 2004 00:03:14 GMT
Viewed: 
1435 times
  
In lugnet.cad.ray, Mike Thorn wrote:
I, like David, am having problems with color as well.

I have used transparent elements before and they have rendered beautifully.
However, in this case there seems to be something wrong and I really don't know
what it is.

I am trying to render a transparent sceptre for my deity minifig. I have set the
lightsabre handle and the gem to be Trans-White. The minifig itself is white.

~ <<http://www.roboticsresources.com/mlcadphoto.jpg>>
~ <<http://www.roboticsresources.com/povrayphoto.jpg>>

(MLCad snapshot colors reduced to 16)

You can see from the dotted lines in the MLCad snapshot that the sceptre and gem
are indeed clear. However, the tracing shows something else. The image shows the
sceptre as white, same as the minifig.

Is there a bug in L3P or PoV-Ray when radiosity settings are used? I have a
custom sky sphere defined and am using Orion's LDRaw radiosity files.

L3P generates exactly the same color definition for 47, 0x06FFFFFF and 0x03FFFFFF,
so normally it shouldn't matter which color you use.

However, you include "ldraw_radiosity.inc" which again includes "LDRAW_RAD_COLORl.inc",
and in this file Color47 is defined - overruling the L3P definition.
But the radiosity files don't define the Color0x06FFFFFF,
so now you get different results.

L3P defines Color0x06FFFFFF with a "#if (QUAL > 1)" statement to enable fast
test renderings. If you set QUAL=2 then you'll get the transparent sceptre with
color 0x06FFFFFF.

To overcome the problem that the radiosity files can't possibly define the millions of
Color0x0XRRGGBB colors, I think I will now let L3P use a macro for these colors, e.g.:
#ifndef (Color0x06)
#macro Color0x06(r,g,b)
material { texture {
   pigment { rgb <r/255,g/255,b/255> #if (QUAL > 1) filter 0.85 #end }
   finish { ambient AMB diffuse DIF }
   #if (QUAL > 1)
      finish { phong 0.5 phong_size 40 reflection 0.2 }
      #if (BUMPS) normal { BUMPNORMAL } #end
   #end
} #if (QUAL > 1) interior { ior 1.25 } #end }
#end
#end

and reference the color like this:
object {
   _30153_dot_dat
   matrix <1-SW/20,0,0,0,1-SW/22,0,0,0,1-SW/20,0,SW/-4.4,0>
   matrix <1,0,0,0,1,0,0,0,1,44,-241,405>
   Color0x06(255,255,255)
}

This enables the radiosity files to overrule the macro.

Macros are new to PovRay 3.1, so I guess this means a definitive farewell to PovRay 3.0...
Any comments, please ?
/Lars



Message is in Reply To:
  More color problems
 
I, like David, am having problems with color as well. I have used transparent elements before and they have rendered beautifully. However, in this case there seems to be something wrong and I really don't know what it is. I am trying to render a (...) (21 years ago, 5-Feb-04, to lugnet.cad.ray, FTX)

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