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On Tue, 02 Apr 2002 17:18:56 -0600, Christopher James Huff <chr### [at] mac com>
wrote:
> You are mistaken. This message means exactly what it says, the camera is
> inside the box. It has nothing to do with finite-vs-infinite
#local B=box{-1 0 inverse};
#local Test = 1+0*x;
#while(inside(B,Test))
#local Test=Test+1;
#end
ABX
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> On Wed, 3 Apr 2002 00:07:32 +0200, "JRG" <jrg### [at] hotmailcom> wrote:
> > That does not make it an infinite object.
> > I can read:
> > "scene contains 1 frame level objects; 0 infinite".
>
> IIRC this counting message consider bounding boxes so nothing strange (but of
> course can confuse).
You know that anything out of the bounding box is just clipped, don't you? So a
finite bounding_box _means_ a finite object.
>
> > Either an inverted object isn't infinite, or that message is wrong.
>
> Another test: make box, add inverse, hollow and media and tell me where media
> appear ?
Nowhere. I tried and it looked plain wrong.
> > BTW, I used difference many times, and my CSG objects never happened to become
> > infinte.
>
> You were lucky. Creation of bounding boxes for CSG isn't so simple to have one
> general rule. IIRC it depends on relation in space, volume, type of csg etc.
> Documentation says about bounding: "For difference and intersection operations
> this will hardly ever lead to an optimal bounding box. It's sometimes better
> (depending on the complexity of the CSG object) to have you place a bounding
> shape yourself using a bounded_by statement."
As a matter of fact I use bounded_by quite often. IIRC my coffee-percolator model
(mostly made of intersected planes) was about 300% faster with my manual bounding.
--
Jonathan.
Home: http://digilander.iol.it/jrgpov
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On Wed, 3 Apr 2002 00:17:27 +0200, "JRG" <jrg### [at] hotmailcom> wrote:
> It's an infinite surface which makes an infinite object.
In my definition it's an infinite volume which makes an infinite object.
ABX
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> On Tue, 02 Apr 2002 17:18:56 -0600, Christopher James Huff <chr### [at] maccom>
> wrote:
> > You are mistaken. This message means exactly what it says, the camera is
> > inside the box. It has nothing to do with finite-vs-infinite
>
> #local B=box{-1 0 inverse};
> #local Test = 1+0*x;
> #while(inside(B,Test))
> #local Test=Test+1;
> #end
This means nothing.
#local B=box{-1 0};
#local Test = 1+0*x;
#while(!inside(B,Test))
#local Test=Test+1;
#end
It's just the same thing. What before was considered 'inside' is now considered
'outside'. This has nothing to do with the finiteness (sp?) of the box.
> In my definition it's an infinite volume which makes an infinite object.
But we're talking about POV-Ray's definition, aren't we?
--
Jonathan.
Home: http://digilander.iol.it/jrgpov
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On Wed, 3 Apr 2002 00:27:03 +0200, "JRG" <jrg### [at] hotmailcom> wrote:
> You know that anything out of the bounding box is just clipped, don't you?
Not at all. It separates rays to perform intersection test. But when
intersection point is outside bounding box but ray goes through bounding box
then it is visible.
Also iirc there is a switch in ini settings.
> So a finite bounding_box _means_ a finite object.
I never saw basic trick with bounding box near camera probably.
> > > Either an inverted object isn't infinite, or that message is wrong.
> >
> > Another test: make box, add inverse, hollow and media and tell me where media
> > appear ?
>
> Nowhere. I tried and it looked plain wrong.
I've not tested proposed example. I was really interested what result it could
produce. Perhaps it could be considered a bug. I don't know.
ABX
--
disc{z,-z#macro O()asc(substr("-+((1*(,1,/.-,*/(,&.323/'1"e,1))*.1-4#declare
e=e-1;#end#local e=26;5pigment{#local g=function(_){ceil(_)-_}function#local
k=function{pattern{object{sphere_sweep{linear_spline 13#while(e)<O(),O()//35
>.01#end}}}}{k(g(atan2(x,y)),g(ln((y+x)^2+1e-5)),0)}}finish{ambient 1}}//ABX
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JRG <jrg### [at] hotmailcom> wrote:
>> An inverted box is infinite.
> No, it's not.
> At least not from POV-Ray's point of view (just try).
In the given example, if I replace "difference" with intersection, the
object becomes finite (POV-Ray reports 1 object, 0 infinite). If I then
make the box inverted, it becomes infinite (POV-Ray reports 1 object,
1 infinite).
By logic, making the box inverted makes it infinite. Difference inverts
internally the second and subsequent objects, which explain what is
happening.
Clipping the whole object (with a proper clipped_by object) makes it
finite (POV-Ray reports 1 object, 0 infinite). This is logical because
now the object has been limited to the clipped_by object, which is finite.
--
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}// - Warp -
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> On Wed, 3 Apr 2002 00:27:03 +0200, "JRG" <jrg### [at] hotmailcom> wrote:
> > You know that anything out of the bounding box is just clipped, don't you?
>
> Not at all. It separates rays to perform intersection test. But when
> intersection point is outside bounding box but ray goes through bounding box
> then it is visible.
Anyway, you get unpredictable results. You cannot consider what is outside the
bounding box part of the object.
The docs say: "Note that if bounding shape is too small or positioned incorrectly it
may clip the object in undefined ways or the object may not appear at all."
> Also iirc there is a switch in ini settings.
>
> > 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. Which trick?
--
Jonathan.
Home: http://digilander.iol.it/jrgpov
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Try any other difference which does not contain a heightfield: do you get an infinite
object? (That could be a problem concerning h-f). And have you really tried the most
simple example: box {-1,1 inverse}?
Like ABX you are thinking in terms of volumes. POV-Ray dislikes that concept.
--
Jonathan.
Home: http://digilander.iol.it/jrgpov
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On Wed, 3 Apr 2002 00:31:53 +0200, "JRG" <jrg### [at] hotmailcom> wrote:
> > In my definition it's an infinite volume which makes an infinite object.
>
> But we're talking about POV-Ray's definition, aren't we?
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.
ABX
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JRG <jrg### [at] hotmailcom> wrote:
> Try any other difference which does not contain a heightfield: do you get an
infinite
> object? (That could be a problem concerning h-f).
This may need a bit of researching.
--
#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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