> I have digged documentation to find definition of finite/infinite and passed so
> therefore reffered to my definition. My definition and my tests tell me that
> inversed box has finite surface and infinite volume and therefore differenced
> with another object can make infinite result.

  However, the difference of two boxes is not infinite.

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -

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On Wed, 3 Apr 2002 00:52:43 +0200, "JRG" <jrg### [at] hotmailcom> wrote:
> Like ABX you are thinking in terms of volumes. POV-Ray dislikes that concept.

Try to make sphere as poly (ready script in documentation of 3.5 ) and tell me
is it finite or infinite ? It has finite surface.

ABX

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On Wed, 3 Apr 2002 00:47:29 +0200, "JRG" <jrg### [at] hotmailcom> wrote:
> > > So a finite bounding_box _means_ a finite object.
> >
> > I never saw basic trick with bounding box near camera probably.
>
> I'm not sure what you want to say.

Somehow I placed I instead of You. It's becouse of 24 hours at work.

> Which trick?

Currently I can't find most typical animation of this type of trick/technic.

ABX

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That's different. POV-Ray doesn't have a clue about how big the poly object may
result (but I can be wrong here. Never used it before.)
I think with poly objects manual bounding is a good habit (note that a bounding box
makes it a finite object: i.e. it cannot exist an infinite object with a finite
bounding box).


--
Jonathan.

Home: http://digilander.iol.it/jrgpov


news:nsekau8uqei7hucgtorjd3f8pv1n8chn4e@4ax.com...
> On Wed, 3 Apr 2002 00:52:43 +0200, "JRG" <jrg### [at] hotmailcom> wrote:
> > Like ABX you are thinking in terms of volumes. POV-Ray dislikes that concept.
>
> Try to make sphere as poly (ready script in documentation of 3.5 ) and tell me
> is it finite or infinite ? It has finite surface.
>
> ABX

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"JRG" wrote:
> That's different. POV-Ray doesn't have a clue about how big the poly object may
> result (but I can be wrong here. Never used it before.)
> I think with poly objects manual bounding is a good habit (note that a bounding box
> makes it a finite object: i.e. it cannot exist an infinite object with a finite
> bounding box).

Here's my new definition: a finite object is an object with a finite bounding box.
Everything else is infinite. He he.

--
Jonathan.

Home: http://digilander.iol.it/jrgpov

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On Wed, 3 Apr 2002 01:28:49 +0200, "JRG" <jrg### [at] hotmailcom> wrote:
> That's different. POV-Ray doesn't have a clue about how big the poly object may
> result (but I can be wrong here. Never used it before.)

Example was reffered to your definition of infinity: "It's an infinite surface
which makes an infinite object."

> it cannot exist an infinite object with a finite
> bounding box.

According to my definition of infinity (volume) it is true but according to your
definition (surface) it isn't. According to output of "Scene contains..." it is
probably ture but....

... is any not inversed not transformed box finite ? Then

plane{y 0 bounded_by{box{-(1e50) 1e50 }}}

:-)

ABX

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On Wed, 3 Apr 2002 01:37:38 +0200, "JRG" <jrg### [at] hotmailcom> wrote:
> Here's my new definition: a finite object is an object with a finite bounding box.

"But we're talking about POV-Ray's definition, aren't we?" ;-)

> Everything else is infinite. He he.

as I already said:

plane{y 0 bounded_by{box{-(1e50) 1e50 }}}

:-)

ABX

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> On Wed, 3 Apr 2002 01:28:49 +0200, "JRG" <jrg### [at] hotmailcom> wrote:
> > That's different. POV-Ray doesn't have a clue about how big the poly object may
> > result (but I can be wrong here. Never used it before.)
>
> Example was reffered to your definition of infinity: "It's an infinite surface
> which makes an infinite object."

Good point. See my new definition. :)

> > it cannot exist an infinite object with a finite
> > bounding box.
>
> According to my definition of infinity (volume) it is true but according to your
> definition (surface) it isn't. According to output of "Scene contains..." it is
> probably ture but....
>
> ... is any not inversed not transformed box finite ? Then
>
> plane{y 0 bounded_by{box{-(1e50) 1e50 }}}

Aw, come on. You know better than me that a box that big is considered infinite by
POV...

--
Jonathan.

Home: http://digilander.iol.it/jrgpov

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On Wed, 3 Apr 2002 01:49:23 +0200, "JRG" <jrg### [at] hotmailcom> wrote:
> Aw, come on. You know better than me that a box that big is considered infinite by
> POV...

So your definition is POV definition and POV definition is sentence witch starts
with "Scene contains ..." , right ?

ABX

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In article <3caa034f@news.povray.org>,
 "Patrick Dugan" <pat### [at] usnetcomcorpcom> wrote:

> #declare One =
> difference {
>    height_field {
>       tga "MyPicture.tga"
>       smooth
>       hierarchy on
>       translate <-0.5, -0.5, -0.5>
>       rotate <-90,0,0>
>       scale <0.3,1,0.1>
>       photons {target reflection on}
>    }
>    box{<-0.2,-0.6,-0.02>,<0.2,0.6,2> pigment {rgbft <1,1,1,0,1>}
>       no_shadow no_reflection no_image photons {collect off}
>    }
>     bounded_by { box{<-5,-5,-5>,<5,5,5>}}
> }

A point is considered "inside" a height_field if it is "below" it. If 
the height_field is not rotated or sheared, all points -y of some part 
of the surface are inside it.

POV seems to have a hard time with this fact in this case, it knows the 
height field isn't bound to a cubic space and that the difference 
surface may occur anywhere, so it considers it to be infinite when 
computing the bounding boxes. A better solution might be to use a box 
extending very far downward for the CSG bounding computations, or to 
limit the height_field object to a cube.

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/

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