Hey all,

Help a poor newbie, please.  :-,

I've been trying to figure out what the docs mean when it differentiates
between hollow and solid objects.

According to the docs, all object are considered to be solid unless
otherwise specified (povuser.pdf v3.1, section 4.6.2).  However, a colormap
with transparent entries doesn't affect anything but the surface.  i.e. if
you have a transparent pigment on an object, you can see right through the
object to the pigment on the other side.  The following code can help
describe what I mean:

#include "colors.inc"
background { color Black }
camera {
  location <0, 2, -3>
  look_at <0, 1, 2>
}
light_source { <2, 4, -3> color White}
// inner sphere
sphere { <0,1,2>, 1
  texture { pigment{ color Red } }
}
// outer sphere
sphere { <0, 1, 2>, 2
  texture {
    pigment {
      bozo
      turbulence 5
      lambda 2
      color_map {
        [ 0 color rgbt<0,0,1,1> ]
        [ 0.5 color rgbt<0.5,0.5,1,0.9> ]
        [ 1 color rgbt<1,1,1,0> ]
      }
      scale 20
    }
  }
}

I was expecting the outer sphere to be something like a solid, lumpy blob in
the general shape of a sphere; but instead I got a textured, hollow sphere
with a shell of zero thickness.  What do I need to do to apply the texture
to the stuff *inside* the object?

Am I looking for an "interior" thing?  I want to think so, but the docs seem
to indicate that the interior keyword is only good for internal atmospheric
effects, and I want a true solid.

Cheers,
 - jsproat

-- 
Jeremy H. Sproat <jsp### [at] iocom>
http://www.io.com/~jsproat
Darth Maul Lives

Post a reply to this message

Sproaticus wrote:
> 
> Hey all,
> 
> Help a poor newbie, please.  :-,
> 
> I've been trying to figure out what the docs mean when it differentiates
> between hollow and solid objects.
> 
> According to the docs, all object are considered to be solid unless
> otherwise specified (povuser.pdf v3.1, section 4.6.2).  However, a colormap
> with transparent entries doesn't affect anything but the surface.  i.e. if
> you have a transparent pigment on an object, you can see right through the
> object to the pigment on the other side.  The following code can help
> describe what I mean:
> 

> 
> Am I looking for an "interior" thing?  I want to think so, but the docs seem
> to indicate that the interior keyword is only good for internal atmospheric
> effects, and I want a true solid.
> 

Interior is the good thing to look at. 
It may also be used to specify the IOR (indice of reflection) of the
object.

Textures only apply to the boundaries of an object.
By default, a pov object is solid, which only means that if you cut it,
the texture will have to apply to the new cut surface. 

If you want an object filled with something different from its external
texture,
so that when you cut it, you see the filling rather that the external
texture,
you need to have a look at "hollow on" and may be to "media"

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See the explanation at
http://www.students.tut.fi/~warp/povVFAQ.html#hollowobjects

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

Post a reply to this message

On Fri, 9 Jul 1999 4:59 PM, J. Grimbert <mailto:jgr### [at] atos-groupcom>
wrote:
>Sproaticus wrote:

[snipped]

>Interior is the good thing to look at. 
>It may also be used to specify the IOR (indice of reflection) of the
>object.

you mean: refraction.

Have Fun
Martin
--
Owner/Operator - Tesseract Computing
<hypercube 'at' tesseract.com.au> or just reply.

Computer Systems Officer - Tourism Tasmania
<Martin.Crisp 'at' tourism.tas.gov.au>

I speak for me.

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