What would be the best way to create water stains on a surface? I haven't
been able to find any way to locate them in a specific location; it seems
to me that the best way will be an image maps, but I'd rather generate
them, since I want it to be different stains down a tunnel - many blocks,
many stains, which will be tiresome to create as an image map.

Thanks!

Jkior

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In article <web.3d9877d4c1649b9311db98c50@news.povray.org>,
 "Jkior" <jki### [at] zworgcom> wrote:

> What would be the best way to create water stains on a surface? I haven't
> been able to find any way to locate them in a specific location; it seems
> to me that the best way will be an image maps, but I'd rather generate
> them, since I want it to be different stains down a tunnel - many blocks,
> many stains, which will be tiresome to create as an image map.

It depends what exactly you want...just a mark from the water level 
being higher in the past than it is now? Use a gradient pattern with 
some turbulence. Marks from water dripping and running down a wall? A 
bit more difficult, an image map would give the most control, but you 
could do it with a function pattern or even an object pattern with a bit 
of turbulence. The object pattern will always give a sharp edge though, 
with no soft edges or differences in color from distance to the stain 
edge.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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Christopher James Huff wrote:
>It depends what exactly you want...just a mark from the water level
>being higher in the past than it is now? Use a gradient pattern with
>some turbulence. Marks from water dripping and running down a wall? A
>bit more difficult, an image map would give the most control, but you
>could do it with a function pattern or even an object pattern with a bit
>of turbulence. The object pattern will always give a sharp edge though,
>with no soft edges or differences in color from distance to the stain
>edge.
>
>Christopher James Huff <cja### [at] earthlinknet>
>http://home.earthlink.net/~cjameshuff/
>POV-Ray TAG: chr### [at] tagpovrayorg
>http://tag.povray.org/
>

I'd like water stains leaking around concrete blocks - so sharp edges won't
be a problem. However, I can't seem to be able to find anything in the
documentation explaining object patterns - "object" and "patterns" are the
ultimate in non-specific search terms in the pov docs. If object patterns
won't work, however, how will it be possible to wrap an image map around
the inside of a toroid (CSG) - a curving tunnel, circular in cross section?

Thanks!

Jkior

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In article <web.3da0f0e5e389b6f1ebbd77600@news.povray.org>,
 "Jkior" <jki### [at] zworgcom> wrote:

> I'd like water stains leaking around concrete blocks - so sharp edges won't
> be a problem. However, I can't seem to be able to find anything in the
> documentation explaining object patterns - "object" and "patterns" are the
> ultimate in non-specific search terms in the pov docs.

The object pattern uses one color/pigment/texture for any points inside 
the object, and another for anything outside. Just look in the patterns 
section of the reference. You could make a union of a lot of objects 
representing all the stained areas, this would be simple but it could be 
slow with a lot of objects. (insideness checking, which is what the 
object pattern uses, is usually very fast, but it could pile up with 
lots of objects)
Another possibility would be to use only the stain objects that affect a 
specific block in the texture, so POV doesn't have to do the insideness 
tests for the stains on the other side of the tunnel. This would use 
more memory and would be a lot more complex, but would be faster.


> If object patterns won't work, however, how will it be possible to 
> wrap an image map around the inside of a toroid (CSG) - a curving 
> tunnel, circular in cross section?

I believe this is possible, there is a toroidal mapping available.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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