POV-Ray : Newsgroups : povray.general : Quick way to darken an object? Server Time
30 Jul 2024 16:22:42 EDT (-0400)
  Quick way to darken an object? (Message 1 to 10 of 10)  
From: SharkD
Subject: Quick way to darken an object?
Date: 22 Dec 2008 23:45:01
Message: <web.49506bbb610ef344364699ad0@news.povray.org>
Is there a quick way of darkening an object after it has already been defined?
I'm using an include file created by someone else, but the object is too light
and I don't want to edit the other person's include file. Thanks!

-Mike


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From: clipka
Subject: Re: Quick way to darken an object?
Date: 23 Dec 2008 01:05:01
Message: <web.49507f7375b63ad3a5987fa00@news.povray.org>
"SharkD" <nomail@nomail> wrote:
> Is there a quick way of darkening an object after it has already been defined?
> I'm using an include file created by someone else, but the object is too light
> and I don't want to edit the other person's include file. Thanks!
>
> -Mike

Put it in a separate light_group and dim the light source for it.

It's problematic though if the object has a nonzero ambient. In that case you
may need to crank down the global ambient_illumination as well, and increase
your own materials' ambient values instead (if they are nonzero as well, that
is).


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From: SharkD
Subject: Re: Quick way to darken an object?
Date: 23 Dec 2008 01:25:01
Message: <web.4950832375b63ad3f7d94b070@news.povray.org>
"clipka" <nomail@nomail> wrote:
> Put it in a separate light_group and dim the light source for it.
>
> It's problematic though if the object has a nonzero ambient. In that case you
> may need to crank down the global ambient_illumination as well, and increase
> your own materials' ambient values instead (if they are nonzero as well, that
> is).

Wow! I had no idea there was such a thing as a light_group. I'd rather pursue a
solution that involves modifying the textures; but I guess that's not possible.
:(

-Mike


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From: SharkD
Subject: Re: Quick way to darken an object?
Date: 23 Dec 2008 02:05:00
Message: <web.49508d3b75b63ad3ac9319ea0@news.povray.org>
"clipka" <nomail@nomail> wrote:
> Put it in a separate light_group and dim the light source for it.
>
> It's problematic though if the object has a nonzero ambient. In that case you
> may need to crank down the global ambient_illumination as well, and increase
> your own materials' ambient values instead (if they are nonzero as well, that
> is).

Actually, this method worked out better than I expected. Thanks for the
suggestion!

-Mike


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From: alphaQuad
Subject: Re: Quick way to darken an object?
Date: 23 Dec 2008 12:15:00
Message: <web.49511c6075b63ad3fa62dc780@news.povray.org>
"SharkD" <nomail@nomail> wrote:
> Is there a quick way of darkening an object after it has already been defined?
> I'm using an include file created by someone else, but the object is too light
> and I don't want to edit the other person's include file. Thanks!
>
> -Mike

Cant' you just object { already-finished-obj finish { new-finish } }

I mean it *will* just overwrite, reset, etc?

aQ


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From: Trevor G Quayle
Subject: Re: Quick way to darken an object?
Date: 23 Dec 2008 12:35:00
Message: <web.495120ee75b63ad381c811d20@news.povray.org>
"alphaQuad" <alp### [at] earthlinknet> wrote:
> "SharkD" <nomail@nomail> wrote:
> > Is there a quick way of darkening an object after it has already been defined?
> > I'm using an include file created by someone else, but the object is too light
> > and I don't want to edit the other person's include file. Thanks!
> >
> > -Mike
>
> Cant' you just object { already-finished-obj finish { new-finish } }
>
> I mean it *will* just overwrite, reset, etc?
>
> aQ

No.  If an object already has a pigment/finish/normal/texture/material, it
doesn't get overwritten.  Only objects without finish etc will pick it up.

-tgq


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From: Mike Williams
Subject: Re: Quick way to darken an object?
Date: 23 Dec 2008 13:11:40
Message: <4pxocwIQnSUJFw6V@econym.demon.co.uk>
Wasn't it alphaQuad who wrote:
>"SharkD" <nomail@nomail> wrote:
>> Is there a quick way of darkening an object after it has already been 
>>defined?
>> I'm using an include file created by someone else, but the object is 
>>too light
>> and I don't want to edit the other person's include file. Thanks!
>>
>> -Mike
>
>Cant' you just object { already-finished-obj finish { new-finish } }
>
>I mean it *will* just overwrite, reset, etc?

No. Any components that already have any part of a texture will retain 
their individual finish.

Consider:

#declare foo = union {
   sphere {0,1 pigment {rgb <1,0,0>}}
   sphere {x,1 }
}
object {foo finish {specular 1}}

Only the unpigmented sphere becomes shiny (I used specular rather than 
ambient or diffuse, because an object with no pigment looks much the 
same whatever you set its ambient or diffuse values to).

-- 
Mike Williams
Gentleman of Leisure


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From: SharkD
Subject: Re: Quick way to darken an object?
Date: 24 Dec 2008 06:30:01
Message: <web.49521cd375b63ad3e190ef1d0@news.povray.org>
"clipka" <nomail@nomail> wrote:
> Put it in a separate light_group and dim the light source for it.
>
> It's problematic though if the object has a nonzero ambient. In that case you
> may need to crank down the global ambient_illumination as well, and increase
> your own materials' ambient values instead (if they are nonzero as well, that
> is).

This makes me wonder whether a camera_group would be possible. I.e., render one
object using an perspective camera, and another using an orthographic camera.

-Mike


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From: clipka
Subject: Re: Quick way to darken an object?
Date: 24 Dec 2008 12:05:00
Message: <web.49526bb175b63ad3568ffff50@news.povray.org>
"SharkD" <nomail@nomail> wrote:
> This makes me wonder whether a camera_group would be possible. I.e., render one
> object using an perspective camera, and another using an orthographic camera.
>
> -Mike

Oh-oh... that sounds to me like it would be an ugly mess :)

You'd very soon run into specification problems: Would you want to adapt the
concept of "distance" for each camera? If so, in what way? If not, you'd most
certainly get perception-of-depth issues in animations. How about reflections
of the object? Without any further messing around, it will seem somewhere else
in mirrors than in the "main show"...

I wouldn't know what it would be good for either. But depending on what you are
up to, maybe you should have a look at MegaPOV - it allows you to define
additional cameras, the "output" of which you can use as patterns.


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From: SharkD
Subject: Re: Quick way to darken an object?
Date: 27 Dec 2008 06:40:05
Message: <49561415$1@news.povray.org>
clipka wrote:
> "SharkD" <nomail@nomail> wrote:
>> This makes me wonder whether a camera_group would be possible. I.e., render one
>> object using an perspective camera, and another using an orthographic camera.
>>
>> -Mike
> 
> Oh-oh... that sounds to me like it would be an ugly mess :)
> 
> You'd very soon run into specification problems: Would you want to adapt the
> concept of "distance" for each camera? If so, in what way? If not, you'd most
> certainly get perception-of-depth issues in animations. How about reflections
> of the object? Without any further messing around, it will seem somewhere else
> in mirrors than in the "main show"...
> 
> I wouldn't know what it would be good for either. But depending on what you are
> up to, maybe you should have a look at MegaPOV - it allows you to define
> additional cameras, the "output" of which you can use as patterns.
> 
> 
> 
I was thinking along the lines of something like this:

http://en.wikipedia.org/wiki/Waterfall_(M._C._Escher)

The background uses perspective projection, but the building does not.

-Mike


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