In article <39DAF661.10825941@skynet.be> , Fabien Mosen 
<fab### [at] skynetbe>  wrote:

>> Yes I am aware of that but I found that it was quite hard to control. Much
>> easier if there was one finish for the whole texture.
>
> And quicker, because currently, if you use a texture-map, the pigment,
> normal and finish are calculated more than once for each pixel.
> If finish was at the same level as texture, the "underlying" texture
> would be calculated just once, no matter the complexity of the "finish
> map".

If I am not completely wrong this is not the case you should be able to put
your pigment and normal stuff in one texture layer and have as many finish
layers as you like in other texture layers.


    Thorsten

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Fabien Mosen <fab### [at] skynetbe> wrote:
: Can you get the normal at that point ? Yes.
: Can you get the color variation caused by reflection at that
: point ? No !

  You are comparing different things.

  Yes, you can get the normal at that point, but you can't get the
color variation caused by the normal at that point.
  In the same way, yes, you can get the finish value at that point but
you can't get the variation caused by the finish at that point.

  Normal and finish are very similar.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):_;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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Fabien Mosen <fab### [at] skynetbe> wrote:
: No, I'm looking for the value BEFORE it's finally affected by the
: projection system.

  You can't get a color caused by a reflection/refraction BEFORE the final
projection system is set. So you are asking for something that is impossible.

: Oh, BTW, interior {ior} depends on normal perturbation (it
: affects the refracted ray).

  You made a wrong statement and then a true statement in parentheses.
  The normal doesn't affect the ior because the ior is constant. Yes, the
normal affects the refracted ray. A reflected/refracted ray is affected
by many things.

: Good question.  Historically, "finish" has been fed with many
: features that didn't fit elsewhere.  "crand" is an example of
: that.  ambient, diffuse and brillance might go into a separate
: statement, (maybe "lighting") which describes how the surface
: reacts to light.

  Since when finish has contained only view-dependant things?

: I can ask POV-Ray to retrieve it and put the rgb value on-screen,
: without even rendering !

  No, you can't.
  Well, you can, but without shading (due to light sources), shadows,
fog, media, radiosity... A kind of +Q0 image.

:> No, you can't see your pigment if there's no camera and light_sources.

  It's perfectly possible to see a pigment without light_sources.
  A scene without a camera doesn't make sense.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):_;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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Warp wrote:

>   Since when finish has contained only view-dependant things?

That's part of the problem !  The MAIN purpose of finish is to set
these view-dependant features : reflection and highlights (which
are faked blurred reflections).  The word "finish" implies that
its the "last" property of a surface : varnish,...

> : I can ask POV-Ray to retrieve it and put the rgb value on-screen,
> : without even rendering !
> 
>   No, you can't.

#declare RGBValue = eval_pigment (MyPigment,<x,y,z>);
#debug concat ("the rgb value at <x,y,z> is ",
                str(RGBValue.x,3,3),str..,str..)

>   Well, you can, but without shading (due to light sources), shadows,
> fog, media, radiosity... A kind of +Q0 image.

All right.  That is the rgb value at that point, which is, "later",
modified by other elements.

>   It's perfectly possible to see a pigment without light_sources.
>   A scene without a camera doesn't make sense.

Thats for the sake of explaining how finish is different from
pigment and normal.  Within some hours, I'll get that diagram
done, and I hope it will make things clearer.

(BTW, you could want to make a scene without a specific camera, just
 to get the results of a particular algorithm that uses POV-Ray's
 specific capabilities)

Fabien.

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Fabien Mosen <fab### [at] skynetbe> wrote:
: That's part of the problem !  The MAIN purpose of finish is to set
: these view-dependant features : reflection and highlights (which
: are faked blurred reflections).  The word "finish" implies that
: its the "last" property of a surface : varnish,...

  And why things like crand, ambient and diffuse are not this kind of things?

:>   It's perfectly possible to see a pigment without light_sources.
:>   A scene without a camera doesn't make sense.

: Thats for the sake of explaining how finish is different from
: pigment and normal.

  Normal is not much different from finish. If you don't have any light
source nor reflection/refraction, applying a normal to a surface has absolutely
no effect. The normal has effect only in the final rendering pass, as well
as finish.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):_;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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Mick Hazelgrove <mic### [at] mhazelgrovefsnetcouk> wrote:
> I like this new structure very much. I've only just come across the need for
> a "finish map" (No, not a map of Finland!)
> this would solve the problem nicely and is much more logical.

Hmm, I came up with this a long time back.  I wanted to do a wood pattern,
and looking at the wood (balsa) I was working from, I noticed a series of
tiny lines perpendicular (or maybe parallel) to the grain that shine more
than elsewhere.  Only way I could do it was a texture map where the pigment
and normal were the same, but the finishes were different.  Having a
separate finish map to allow for finishes that vary over the surface while
the texture does not could be nice.

On the other hand, where textures are also varying, it requires two maps
with the same entry values (to do what used to be done), but I'm not sure
that's a good reason *not* to do it.  Certainly making them independent
allows for a lot of new possibilties (ex: Textures vary based on granite
pattern, while finishes based on bump, or whatever)

Geoff

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No comments, thoughts, critiques?

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Fabien,

if I have understood you correctly you're saying that finish is
view-dependent, while pigment and normal are not. I have tried several times
to explain why that is not true, but apparently have failed.

I will now try to explain it using some clearer expressions. I will use
"property" contra "appearance". These should not easily be mixed up.

In the pigment you specify the colour(s) of your object. If you make a
sphere with a white pigment, then a property of the sphere is that it is
white. Even if your object is lit by a red light_source only, the colour
property of the sphere is *still* white. The *appearance* however, is *red*
(and very dark red where it is in shadow).

Note that the surroundings don't affect the property of the object, but they
do affect the appearance.

Now to the normal. A property of an object can be it's slope at a given
point. This slope is independent on the surroundings (lights, camera, etc.).
However, the *appearance* of the slope is dependent on many things which I
will not go into details with here.

In the finish you specify many properties of the object. Ambient, diffuse,
the amount of reflection, highlights, and many other things. The values you
specify are the properties of the object. They are independent of the
surroundings (view-independent). Only the *appearance* is dependent on the
surroundings.

When you want to measure the reflected rays for an object, that is related
to the appearance, not the property of the object.

So for the pigment you want to measure a property.
And for the normal you want to measure a property.
But for the finish you want to measure the appearance!!!

So as I have said many times before, you can't compare like that.

Rune
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Tony[B] wrote:
> 
> No comments, thoughts, critiques?

Well, after having just read thru all the posts on this subject, all I
have to say is "How many Angles can dance on the head of a pin?"

Ken Matassa

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On Sat, 07 Oct 2000 20:04:30 -0700, Ken Matassa wrote:
>Tony[B] wrote:
>> 
>> No comments, thoughts, critiques?
>
>Well, after having just read thru all the posts on this subject, all I
>have to say is "How many Angles can dance on the head of a pin?"

That's acute question, but you're right.  Maybe we're being too obtuse.

-- 
Ron Parker   http://www2.fwi.com/~parkerr/traces.html
My opinions.  Mine.  Not anyone else's.
Proudly not helping RIAA and SDMI steal my rights -- 
  http://www.eff.org/Misc/EFF/Newsletters/EFFector/HTML/effect13.08.html

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