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news:cq6m0l$65g$1@chho.imagico.de...
> It is not a good idea to start demanding a new feature just because it
> is not obvious to you how to accomplish a certain effect with existing
> means.
You can do it with texture_map, but it's not very practical if you want to
have separate maps for more than 2 different channels. To create a finish
pattern independent from the pigment pattern we have currently:
texture{
Pattern_Finish
texture_map{
[0 pigment{Pattern_Pigment} finish{Finish_1}]
[1 pigment{Pattern_Pigment} finish{Finish_2}]
}
}
But if you want to have diffuse values following a pattern different from
the reflection pattern, it's necessary to nest texture maps, which can turn
into a headache:
texture{
Pattern_Reflection
texture_map{
[0
Pattern_Diffuse
texture_map{
[0 pigment{Pigment_Pigment} finish{Finish_1}]
[1 pigment{Pattern_Pigment} finish{Finish_2}]
}
]
[1
Pattern_Diffuse
texture_map{
[0 pigment{Pattern_Pigment} finish{Finish_3}]
[1 pigment{Pattern_Pigment} finish{Finish_4}]
}
]
}
}
Where Finish_1 etc. correspond to the different combinations of diffuse and
reflection, for instance
diffuse 0.5 reflection{0,0.5}
diffuse 0.5 reflection 0
diffuse 1 reflection{0,0.5}
diffuse 1 reflection 0
If patterns could be applied independently to all channels, this would look
like this:
texture{
pigment{Pattern_Pigment + pigment parameters}
diffuse{Pattern_Diffuse + diffuse parameters}
reflection{Pattern_Reflection + reflection parameters}
}
G.
--
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters
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Gilles Tran wrote:
>
> You can do it with texture_map, but it's not very practical if you want to
> have separate maps for more than 2 different channels.
I never said anything how practical this is - just that it is possible.
So the correct way of making this suggestion would have been "I find
it cumbersome to do this currently and therefore suggest the following
change in language design".
>
> If patterns could be applied independently to all channels, this would look
> like this:
> texture{
> pigment{Pattern_Pigment + pigment parameters}
> diffuse{Pattern_Diffuse + diffuse parameters}
> reflection{Pattern_Reflection + reflection parameters}
> }
So you suggest to give up the idea of a finish structure and have all
surface properties as top level items in the texture. I am not saying
this could not be a useful concept but it is fairly out of question that
this could happen any time soon (the changes required for that would be
larger than any change in POV-Ray since version 3.1 at least).
Also note that using this instead of a texture map causes a lot of
unnecessary pattern evaluations if you use the same pattern for several
finish properties. It would therefore be faster to use a texture map in
a lot of cases.
Christoph
--
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 23 Sep. 2004 _____./\/^>_*_<^\/\.______
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Mael already has a working version of this in MLPOV:
http://martial.rameaux.free.fr/mael/help83/ar01s08.html
I haven't tried it myself, but it looks quite interesting.
Peter Duthie
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cq7666$97l$1@chho.imagico.de...
> So you suggest to give up the idea of a finish structure and have all
> surface properties as top level items in the texture. I am not saying
> this could not be a useful concept but it is fairly out of question that
> this could happen any time soon (the changes required for that would be
> larger than any change in POV-Ray since version 3.1 at least).
Such a drastic change cannot be done for POV-Ray 3.x but it could be
considered for a future version. Usually, after 1 level of texture_map
nesting, my brain starts melting down when defining textures in POV-Ray,
while I don't have this problem when using separate channels in other
softwares ;-)
Really, having all surface properties independent and controllable by a
combination of a pattern + specific modifiers is extremely efficient when
creating textures and gives a lot of flexibility.
G.
--
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters
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Gilles Tran wrote:
>
> Such a drastic change cannot be done for POV-Ray 3.x but it could be
> considered for a future version. Usually, after 1 level of texture_map
> nesting, my brain starts melting down when defining textures in POV-Ray,
> while I don't have this problem when using separate channels in other
> softwares ;-)
It would be possible to simplify this with a macro.
> Really, having all surface properties independent and controllable by a
> combination of a pattern + specific modifiers is extremely efficient when
> creating textures and gives a lot of flexibility.
I would like to repeat that when using the same pattern for several
properties (which will very often be the case) this will result in
unnecessary pattern evaluations. You could try to introduce a kind of
pattern cache for this but this would be quite complicated.
Christoph
--
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 23 Sep. 2004 _____./\/^>_*_<^\/\.______
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
Christoph Hormann wrote:
| I would like to repeat that when using the same pattern for several
| properties (which will very often be the case) this will result in
| unnecessary pattern evaluations. You could try to introduce a kind of
| pattern cache for this but this would be quite complicated.
|
Nobody said to *replace* the current implementation with these. It
could conceivably be an addition in which case it would still be
possible to use texture maps when one wants the same pattern for all
the attributes and have only one pattern evaluation in that case.
Jerome
- --
******************************
* Jerome M. Berger *
* mailto:jbe### [at] ifrance com *
* http://jeberger.free.fr/ *
******************************
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Version: GnuPG v1.2.4 (GNU/Linux)
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hr/uQKhcFMvuxjZkiDhOKnk=
=DZUV
-----END PGP SIGNATURE-----
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Seems to me that image mapping different channels is inherently more
sensible and better controlled than nesting a whole lot of material maps
and so on, particuarly when using UV mapping for objects created in other
modelers and imported as meshes with UV information. I am fully aware of
how you 'could' do this effect already in POV but it would be considerably
simpler if POV were able to cope with multiple image channels, and I don't
believe it would make a difference to rendering times since other renderers
do use this technique and are not slower (in fact they can be much faster)
than POVRay. So perhaps I should apologise to the angry masses for not
being as linguistically sensitive as I might have been. You know one
really shouldn't get so touchy over software one didn't pay for.
L
-
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Loki wrote:
> Seems to me that image mapping different channels is inherently more
> sensible and better controlled than nesting a whole lot of material maps
> and so on,
Who did ever talk about nesting material maps ???
> if POV were able to cope with multiple image channels,
What is that supposed to mean now - at least it has nothing to do with
the rest of the thread (which is about patterened finish attributes).
> and I don't
> believe it would make a difference to rendering times since other renderers
> do use this technique and are not slower (in fact they can be much faster)
> than POVRay.
Even apart from the unsupported claim of 'other renderers' being much
faster i seriously hope you do not really believe this argumentation.
Christoph
--
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 23 Sep. 2004 _____./\/^>_*_<^\/\.______
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> > if POV were able to cope with multiple image channels,
>
> What is that supposed to mean now - at least it has nothing to do with
> the rest of the thread (which is about patterened finish attributes).
Either you have no experience of the texturing techniques I refer to or you
are being deliberately obtuse in not recognising what I am talking about
when I discuss mapping different images to different channels. Yes, of
course I refer to patterned finish attributes, and bump channels as well as
colour channels. Mapping images to these channels independently is, I hate
to say it, much more sophisticated than POV's approach. Yes, you can do
the same thing in POV if you do a lot of fiddling, but with the feature I
outlined, specifically being able to map images independently to different
channels within a finish or normal block, the creation of multi-channel
textures in Photoshop, for example, would be as simple as it is in
expensive packages like Maya.
I also stand by my claim that this wouldn't slow down rendering beyond
eminently usable speeds, since it doesn't do so in other renderers. Yes,
it would require a call to an image map for the specular value at a certain
point on an object (for example) but that's no more effort than making the
call to determine the colour at a point of the object; therefore it
shouldn't take any longer to render a single colour object with
image-mapped specular channel than it would to render an image-mapped
object with a single specular value. The advantage is of course in
combining the two, in which case you could have, for example, a
colour-textured metal object with the effect of greasy fingerprints
independently produced in the reflection and specular channels. Using UV
mapping on an object would allow a lot of control over exactly where the
fingerprint appears. This kind of thing is trivial to achieve if the
channels can be mapped independently but very difficult with POVs current
texturing method. Combining POVs physically realistic rendering, which is
undoubtedly powerful, with a more robust texturing scheme as used in other
modelers would result in much wider flexibility in achievable materials.
L
-
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Loki wrote:
>
>
> Either you have no experience of the texturing techniques I refer to or you
> are being deliberately obtuse in not recognising what I am talking about
> when I discuss mapping different images to different channels.
Speaking only for myself, considering this is a POV-Ray news server, the
former is not only a safe assumption for the masses, it would be a
constructive assumption.
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