Hi.

1
I have a cylinder and would like to know, if it is possible to make that
cylinder appear like made of thousands of hexagonal facets, in the way the
cylinder reflects light or how its shaded areas are.

2
Some materials in nature or our environment appear being in one color when seen
from one angle, but when the viewer's angle changes, they appear in another
color. Does POV-Ray allow such an effect, and if, how?

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Am 04.02.2013 19:36, schrieb Sven Littkowski:

> 1
> I have a cylinder and would like to know, if it is possible to make that
> cylinder appear like made of thousands of hexagonal facets, in the way the
> cylinder reflects light or how its shaded areas are.

Depends on what exactly you want to achieve. How about the hexagon 
pattern with a cylindrical warp?

> 2
> Some materials in nature or our environment appear being in one color when seen
> from one angle, but when the viewer's angle changes, they appear in another
> color. Does POV-Ray allow such an effect, and if, how?

That's a definite yes: The aoi pattern (new in POV-Ray 3.7) was added 
with exactly such effects in mind.

You might also want to try the irid keyword, although it only caters to 
one particular angle-dependent physical effect (thin film interference). 
Its implementation in 3.6 was crappy, but it has been reworked for 3.7.

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Sven Littkowski wrote:

> I have a cylinder and would like to know, if it is possible to make that
> cylinder appear like made of thousands of hexagonal facets, in the way the
> cylinder reflects light or how its shaded areas are.

the facets pattern will do something like this but without exact
control over the shape of the facets.

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Thanks to both of you, I will try out these features.   :-)

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Hmmm.......

Problem 1:
I want to wrap the hexagons around a cylinder shape. But the hexagon pattern is
just along the x and z axis. Honestly, at the moment I am out of ideas. Hoped it
would have been three-dimensional.

Problem 2:
Hexagon is a pigment pattern, but my intention is to fill the hexagons with a
texture. One with a dark texture, one with a lighter texture. And then, using
both of them in a texture map.

Problem 3:
I need thin outline (borders) between the hexagons. Those will be filled with a
non-reflective texture.

Oh, oh, oh...

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"Sven Littkowski" <nomail@nomail> wrote:
> Hmmm.......
>
> Problem 1:
> I want to wrap the hexagons around a cylinder shape. But the hexagon pattern is
> just along the x and z axis. Honestly, at the moment I am out of ideas. Hoped it
> would have been three-dimensional.
>
> Problem 2:
> Hexagon is a pigment pattern, but my intention is to fill the hexagons with a
> texture. One with a dark texture, one with a lighter texture. And then, using
> both of them in a texture map.
>
> Problem 3:
> I need thin outline (borders) between the hexagons. Those will be filled with a
> non-reflective texture.
>
> Oh, oh, oh...

Problem 1: use a cylindrical warp on the pattern (3.5.12.6.5 Mapping using
warps)

Problem 2: Hexagon can be used a a textire pattern, check the 4th example under
3.5.11.21 Hexagon

Problem 3: A little more difficult, but could be done.  Best way may be with a
function pattern, but coul also be done by manipulating gradient patterns

-tgq

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"Trevor G Quayle" <Tin### [at] hotmailcom> wrote:
> "Sven Littkowski" <nomail@nomail> wrote:
> > Hmmm.......
> >
> > Problem 1:
> > I want to wrap the hexagons around a cylinder shape. But the hexagon pattern is
> > just along the x and z axis. Honestly, at the moment I am out of ideas. Hoped it
> > would have been three-dimensional.
> >
> > Problem 2:
> > Hexagon is a pigment pattern, but my intention is to fill the hexagons with a
> > texture. One with a dark texture, one with a lighter texture. And then, using
> > both of them in a texture map.
> >
> > Problem 3:
> > I need thin outline (borders) between the hexagons. Those will be filled with a
> > non-reflective texture.
> >
> > Oh, oh, oh...
>
> Problem 1: use a cylindrical warp on the pattern (3.5.12.6.5 Mapping using
> warps)
>
> Problem 2: Hexagon can be used a a textire pattern, check the 4th example under
> 3.5.11.21 Hexagon
>
> Problem 3: A little more difficult, but could be done.  Best way may be with a
> function pattern, but coul also be done by manipulating gradient patterns
>
> -tgq

For 3 I forgot about tiling patterns: (3.5.11.39 Tiling) looks like pattern #8
is hexagonal.

-tgq

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> "Trevor G Quayle" <Tin### [at] hotmailcom> wrote:
>> "Sven Littkowski" <nomail@nomail> wrote:
>>> Hmmm.......
>>>
>>> Problem 1:
>>> I want to wrap the hexagons around a cylinder shape. But the hexagon pattern is
>>> just along the x and z axis. Honestly, at the moment I am out of ideas. Hoped it
>>> would have been three-dimensional.
>>>
>>> Problem 2:
>>> Hexagon is a pigment pattern, but my intention is to fill the hexagons with a
>>> texture. One with a dark texture, one with a lighter texture. And then, using
>>> both of them in a texture map.
>>>
>>> Problem 3:
>>> I need thin outline (borders) between the hexagons. Those will be filled with a
>>> non-reflective texture.
>>>
>>> Oh, oh, oh...
>>
>> Problem 1: use a cylindrical warp on the pattern (3.5.12.6.5 Mapping using
>> warps)
>>
>> Problem 2: Hexagon can be used a a textire pattern, check the 4th example under
>> 3.5.11.21 Hexagon
>>
>> Problem 3: A little more difficult, but could be done.  Best way may be with a
>> function pattern, but coul also be done by manipulating gradient patterns
>>
>> -tgq
>
> For 3 I forgot about tiling patterns: (3.5.11.39 Tiling) looks like pattern #8
> is hexagonal.
>
> -tgq
>
>


Hexagonal tiling pattern:
Pattern 2 (pure hexagon, all identical)
It can have a transparent center and be layered over the hexagon 
pattern. You need to provide a color_map. It's transition point will 
determine the thickness of the edges. It may need some scalling to make 
the 2 patterns match.



Alain

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Am 05.02.2013 16:28, schrieb Sven Littkowski:
> Hmmm.......
>
> Problem 1:
> I want to wrap the hexagons around a cylinder shape. But the hexagon pattern is
> just along the x and z axis. Honestly, at the moment I am out of ideas. Hoped it
> would have been three-dimensional.

That's why I mentioned the cylindrical warp.


> Problem 2:
> Hexagon is a pigment pattern, but my intention is to fill the hexagons with a
> texture. One with a dark texture, one with a lighter texture. And then, using
> both of them in a texture map.

There's nothing stopping you from using the hexagon pattern with 
textures; quote from the docs:

   texture {
     hexagon
     texture { T_Gold_3A },
     texture { T_Wood_3A },
     texture { Stone12 }
     }

As for using two textures, that won't fly: To color a hexagonal tiling 
in such a way that no two adjacent hexagons have the same color, you 
need at least 3 colors.


> Problem 3:
> I need thin outline (borders) between the hexagons. Those will be filled with a
> non-reflective texture.

Have a look at the new "tiling" pattern.

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