Hi.

I think I have found a bug in POVRay. I'm trying to make several
concentric spheres which are all completely transparent, but which have a
reflection. If I make three or more transparent objects inside one
another, the inmost ones will be rendered totally black.

For example the following code:
---snip---
#include "colors.inc"
camera { location <0, 0, -2>  look_at 0 }
light_source { <1,1,-2> White*8 }
plane { -z, -2   pigment { Green } }

#declare COUNT=0.1;
#while (COUNT<0.31)
sphere {
        <0,0,0>,COUNT
        pigment { transmit 1.0 }
}
#declare COUNT=COUNT+0.1;
#end
---snip---

If the number 0.31 is changed to 0.21 (so there are only two concentric
spheres), the image renders, as expected, to a totally green image. But
with 0.31 or larger, there is a black sphere in the middle of the image.
(It gets bigger with larger values, so that the third outmost object is
always black.)

I originally noticed it in the Debian version "3.02.Linux.cc", but trying
the official Linux version "3.1g.Linux.gcc" didn't help. I've also tried
changing want of the options (eg. bounding box on/off), but nothing has
helped.

I'm sorry if this is a known bug/feature, but I couldn't find any info
about it. If there's a way around this, I'd be grateful if you could tell
me how to do it. (It's for a project of mine which is in a bit of a
hurry.)


(I sent this originally to tea### [at] povrayorg, they suggested I post it
here.)

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 /____\   Sampo Niskanen <=> sam### [at] ikifi  \
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