Nekar Xenos:
> I.m starting to feel a bit guilty giving advice left and right, knowing
> how I have trouble myself, just getting the atmosphere right or the
> transparency.

I can't play a musical instrument, but I wont let that stop me from saying
'I like the melody in that song'. I value and appreciate your suggestions as
I do everyone else's - even the axe wielding ones  (Dan)  ;-)

And I am inclined to agree with you, the innner reflections should be more
bubble like rather than covering the entire swirly bit. But I confess, at
the moment I cannot think of how to go about doing this. I'll think on it
and see what I can come up with.

Thanks once again for your thoughts.
--
Duncan Gray
(warning: may contain traces of nut)

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"Duncan Gray" <dun### [at] eclipsecouk> wrote in message
news:3a91a041$1@news.povray.org...
>
> Any idea how they make them ? Glass marbles that is, not ceramic.

http://www.marblemuseum.org/articles/ribboncore.html  about marble making

and

http://www.marblealan.com/reprohand/  which tells of the Atlanta Porcelain
marbles.  Apparently they aren't genuine "marbles".  :-(  Disappointing but
I hardly paid anything for them.  Another place tells of many other such
fakes in the marble collecting realm.  I should have known  :-)  Well, these
I have just might be some kind of old porcelain anyway, painted over, from
some mill I read at one place.  They have cracks and look old.  Seems an
elaborate way to get 50 cents a piece.  Guess I should have checked up on it
at the time but it was soon after the Olympics that I bought these at a
antiques store.

Bob H.

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Thanks Bob - thats great - just what I've been looking for.

Now why didn't altavista tell me about that.

Cheers
--
Duncan Gray
(warning: may contain traces of nut)

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Thank you everyone for your comments and suggestions.

I'm fairly happy now with the surface or the marble (the chipped normal),
and though the swirly bits are still not quite right, they are much closer,
and I think I now have an algorythm will work, it's just a matter of tuning
the parameters a bit more. The colour of the marble has also been changed
slightly to give a greenish hue (thanks to those who suggested this, it does
I think improve the look)

Problem now is with the shadows which are being cast by the marble, looking
at the shadow of the broken marble nearest the camera - the JPEG-type effect
around the dark shadow I am happy with - this is caused by the area light,
and can be lessened up by increasing the number of elements in the area
light source (currently 5x5) and by adding the jitter keyword.

The bit which is concerning me is within the shadow of the semi-transparent
part of the marble, the colours are not blending well - it gives me the
impression of an image which has either been heavily compressed when
converting into JPG or an image which has been enlarged and smoothed,
neither of which are the case.

the light source is as follows:

light_source

  lamp1_pos
  color 1

  area_light <3,0,0>,<0,0,3>,5,5
    adaptive 1

  spotlight
    radius 3
    falloff 6
    point_at lamp1_tgt
}

Can anyone help me out with this little problem ? Am I doing something wrong
with this light source - I'm not sure if you are meant to combine area_light
and spot_light in a single light source, but I couldn't find anything to say
I cannot.

The tiles have a normal on them, though it is fairly subtle. they are
slightly reflective also, might these factors be contributing to the effect
?

Thanks in advance for your suggestions.
--
Duncan Gray
(warning: may contain traces of nut)

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Attachments:
Download 'marbles.jpg' (68 KB)

Preview of image 'marbles.jpg'

It looks pretty good. I'm not sure how marbles would fracture but i'm not gonna
get up roght now and go find out... the texturing is good and I see you fixed
the spirals :)

--
David Fontaine  <dav### [at] faricynet>  ICQ 55354965
My raytracing gallery:  http://davidf.faricy.net/

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very nice, dunno if marbles do break cleanly in half - never really tried to
break one :)


--
Rick

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We used to fry 'em . . . place a few in a frying pan, get 'em hot
and quench them in cold water . . . great look and rarely did
they break on their own.  However, some would break-up if
you dropped 'em after that.  Try it . . . you'll like it :)
--
Y

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David Fontaine wrote:
> It looks pretty good. I'm not sure how marbles would fracture but i'm
> not gonna get up roght now and go find out... the texturing is good and
> I see you fixed the spirals :)

Thank you.

The nature of the break is guess-work - I have never seen a marble break in
two, but I am assuming it would break something like sheet glass - on the
whole smoothly, but with rough jaggy patches.

Spirals are not finished with yet, but I think are a big improvement on my
initial attempt.

I think I've just solved my shadow problem as well - it's not the shadow;
it's the reflection in the tile.  Doh !

Thanks again.
--
Duncan Gray
(warning: may contain traces of nut)

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Finally I have the image to a point where I am happy to call it finished.

It has taken a while to render all the variants, but versions are now
available at 800x600, 1024x768 and 1152x864 for those who wanted them. I
have made available ZIP files containing the POV-Ray generated TGA files in
case you'd rather view the image without JPG compression artifacts. I have
ZIPed them, but they are still rather large.

Rather than post it all to the server, I have made them available on my own
web-site for download and just posted the 800x600 JPG version, the source is
also there for anyone who might like to investigate it.

<www.eclipse.co.uk/duncang/download/marb800.zip> 800x600 tga (725k)
<www.eclipse.co.uk/duncang/download/marb1024.zip> 1024x768 tga (1107k)
<www.eclipse.co.uk/duncang/download/marb1152.zip> 1152x864 tga (1335k)

<www.eclipse.co.uk/duncang/download/marb800.jpg> 800x600 jpg (70k)
<www.eclipse.co.uk/duncang/download/marb1024.jpg> 1024x768 jpg (102k)
<www.eclipse.co.uk/duncang/download/marb1152.jpg> 1152x864 jpg (122k)

<www.eclipse.co.uk/duncang/download/marb_src.zip> source code (4k)

Thanks for your suggestions and comments over the last week or so, I hope
like the final image is to your liking.

--
Duncan Gray
(warning: may contain traces of nut)

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Attachments:
Download 'marb800.jpg' (70 KB)

Preview of image 'marb800.jpg'

Very nice. Much more like the marbles of my misspent youth. Just a couple of
minor comments :
1) In the marbles that I have seen (as recently as last weekend), the
different coloured leaves are joined in the middle edge - this may well vary
across manufacturers.
2) The coloured leaves are too close to the top of the glass. This may just
be something to do with viewing angle but I would expect more of a gap.




"Duncan Gray" <dun### [at] eclipsecouk> wrote in message
news:3a99a36f@news.povray.org...
> Finally I have the image to a point where I am happy to call it finished.
>

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