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4 Aug 2024 02:17:00 EDT (-0400)
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From: Texel
Subject: bumpmapping problem
Date: 30 Aug 2003 13:50:00
Message: <web.3f50e35b88b423b9c6e6d900@news.povray.org>
I have a problem with bumpmapping when my material do not have a diffuse
texture (just color).
How do i have to set the material?

You can download my scene here (56Ko):
http://texel3d.free.fr/bugs/bump_prob.zip

In this scene i display the same object (a sphere) with the same
bumpmapping, but with diffuse texture for the first one (and it works), and
just color for the 2nd (and it doesn't work).

I use this material:

#declare material01 = texture {
pigment { color rgb<0.937255, 0.811765, 0.811765> }
   finish { ambient 0.300000}
   finish { diffuse 0.700000}
   finish { specular  0.200000}
   normal {
      bump_map {
      gif "bump.gif"
      bump_size 50
      interpolate 2
      }
   }
}

Thanks.


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From: Hugo Asm
Subject: Re: bumpmapping problem
Date: 30 Aug 2003 17:23:54
Message: <3f5115ea$1@news.povray.org>
Bump mapping is not visible in ambient light (I mean the "ambient" keyword
in the finish statement) because it's assumed that ambient light comes from
everywhere, so there are no shadows. When you remove diffuse, there is only
ambient light left, along with a vague specular that -does- react to bump
mapping. But maybe it's too vague to be seen in this particular scene.

Better results can be obtained by using radiosity (global illumination) to
replace "ambient" light.

Regards,
Hugo


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From: Texel
Subject: Re: bumpmapping problem
Date: 30 Aug 2003 18:05:01
Message: <web.3f511ebe47b3ca758e547c150@news.povray.org>
I have tried to render the example file of the PovRay package named
"bumpmap.pov" and it works very well.
And this example use diffuse color (without texture) and use ambient.
And the texture i use for my scene work with this example (it's not a
problem of my texture).
Why does it not work with my scene ?


bumpmap.pov file:

global_settings { assumed_gamma 2.2 }

#include "colors.inc"

camera {
   location  <0, 0, -120>
   direction <0, 0,  1.5>
   up        <0, 1,  0>
   right   <4/3, 0,  0>
   look_at   <0, 0,  0>
}

sphere { <0, 0, 0>, 25
   pigment {Blue}

   normal {
      bump_map {
         //png "bumpmap_.png"
         gif "bump.gif"
         bump_size 5
         interpolate 2
         once
      }
      scale 50              /* scaled and translated into position  */
      translate <-25, -25, 0>
   }
   finish {ambient 0.2 diffuse 0.7 specular 0.6}
}

plane { y, -25
   pigment {Gold}
   finish {ambient 0.1 diffuse 0.5}
}

light_source {<100,120,-130> colour White}


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From: Hugo Asm
Subject: Re: bumpmapping problem
Date: 30 Aug 2003 18:21:24
Message: <3f512364$1@news.povray.org>
Ok, I looked at your scene file now.  :o)  The solution is:
Material01 needs uv_mapping to behave like Material02.

Regards,
Hugo


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From: Texel
Subject: Re: bumpmapping problem
Date: 31 Aug 2003 05:55:01
Message: <web.3f51c4f847b3ca757dc634e10@news.povray.org>
Thanks.
It works!


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