Warp wrote:

> Angelo 'kENpEX' Pesce <ken### [at] uniplanit> wrote:
> : 7) displacement mapping
> 
>   Not possible.
>   (Well, possible for meshes, but then you need to tesselate the objects.)
> 

It came to me that displacement mapping is almost like isosurfaces. For 
example, a displacement mapped sphere is an isosurface described by
a sphere + displacement function. So I would not call it impossible (or
only for meshes) but "just" computationally heavy.

By the way, unless you are looking carefully at borders, displacement 
mapping is just undistinguishable from normal fudging.

Bye!!!

Alessandro Coppo
REM### [at] iolit

Post a reply to this message

On Thu, 06 Dec 2001 11:21:47 GMT, ken### [at] uniplanit (Angelo 'kENpEX' Pesce) wrote:
> Mhmm... I think that the raytracer should support those surfaces
> directly as it's hard for a modeller to do accurate tessellation.

It could be hard. IMO modellers differ in implementation of patched surfaces,
nurbs, splines etc.

> I know if I have only one big nurbs model and an infinite plane, i can
> use max tessellation and go with this... But if I have a complete,
> complex scene, with many nurbs characters and a complex background, I
> don't want to alter manually the tessellation parameters for every
> object if it's far away or near the camera...

With POV you are doing everything manually :-)

ABX
--
#declare _=function(a,b,x){((a^2)+(b^2))^.5-x}#default {pigment{color rgb 1}}
union{plane{y,-3}plane{-x,-3}finish{reflection 1 ambient 0}}isosurface{ //ABX
function{_(x-2,y,1)|_((x+y)*.7,z,.1)|_((x+y+2)*.7,z,.1)|_(x/2+y*.8+1.5,z,.1)}
contained_by{box{<0,-3,-.1>,<3,0,.1>}}translate z*15finish{ambient 1}}//POV35

Post a reply to this message

<abx### [at] babilonorg> wrote:

>On Thu, 06 Dec 2001 11:13:27 GMT, ken### [at] uniplanit (Angelo 'kENpEX' Pesce) wrote:
>> I'm only saying
>> that as I'm a softimage user, and many (many) other ppl use maya, or
>> 3dsmax (bleah!), povray should support them better
>
>But ... povray supports them better.
>Povray has well documented SDL which is independent platform for modelers.
>Moray works this way, many apps work this way.
>IMO it is not rule of pov-team to write good plugins for other apps to export
>scripts. IMO it is politic of high-expensive apps to not support _free_
>renderers. But it is personal opinion.

Well mabye this is the politic of high-expensive apps (dunno, I don't
see this politic, but mabye it is, or if it isn't it will be :P), and
I know that pov-team should not work to maya or softimage exporters.
But they could extend the SDL so that writing such exporters is easier
and comfortable...

>> > > Of course supporting both stuff will not hurt at all... :)
>> > And that's what POV has. Support for meshes and primitives. Make unlimited
>> > features with SDL or own patch and enjoy it.
>> As I already told U support for meshes is not enough... And I know
>> that I could make a patch and enjoy nurbs in povray, but as I have to
>> make a patch to enjoy nurbs in povray I'm saying here "please try to
>> support nurbs too"... :)
>Does 3ds (or other apps) support nurbs during tracing or generate triangles
>first and then perform rendering ? Why pov should support nurbs when modelers
>has implemented conversion from nurbs to triangles ? I don't want to say it
>shouldn't. I just think there are more important problems belonging to tracing.
>With good paper I can implement nurbs via macros. With functions{} I have nearly
>shader. I can't improve radiosity or media with macros or functions.

Well I can't tell that as many 3d gfx packages are coupled with a
default raytracer so it's difficoult to say when or where the modeller
ends and the raytracer starts... Ah yes, the thing that I can say to
you is that renderman scene language does support those primitives
natively, so as many renderers use that language they have to support
this stuff natively. I would like to tell U if mentalray does the same
too but I don't know (I don't think so as U can alter tessellation in
the editor, but who knows, mabye it passes the tessellation parameters
to the renderer...) So after all I still think, "yes it should support
them" :P

Update: I've found that mental ray supports nurbs too:
2.2. Curve and surface geometry





and arbitrary basis matrix, Taylor; rational and non-rational

any number of trimming curves, hole curves, and special curves and
points (that control tessellation) can be applied to free-form
surfaces

maximum free-form curve and surface degree of 21

adjacency detection (automatic detection and merging of neighboring
surfaces)

edge merging (cracks in inaccurate models are ``healed'')

curve approximation: 
two parametric modes 
edge length limit 
analytical distance limit 
angle limit 
view-dependent: closer objects are tessellated with more detail 

surface approximations: 
two parametric modes 
edge length limit 
analytical distance limit 
angle limit 
view-dependent: closer objects are tessellated with more detail 
Delaunay (can be combined with the above modes) 
graded Delaunay (can be combined with the above modes) 


quads (Catmull-Clark scheme) 
triangles (Loop scheme) 
wavelet-based multiresolution editing and data compression/LOD 
local refinement (per-face precision assignment) 
texturing 
sharp features: creases and points 
conversion from and to NURBS 
C++ modeling API 
displacement mapping: 
separate refinement approximations: parametric, edge length, distance,
angle; view dependency 
only small portions of a displacement-mapped object are tessellated as
needed. This allows very precise sub-pixel displacement that resolves
even the finest detail of the displacement map, without excessive
memory consumption 

So as U can see it's not the modelling program that should do it...
Another example? Lightflow, bmrt...

Are U still sceptical about this??
>ABX
>--
>#declare _=function(a,b,x){((a^2)+(b^2))^.5-x}#default {pigment{color rgb 1}}
>union{plane{y,-3}plane{-x,-3}finish{reflection 1 ambient 0}}isosurface{ //ABX
>function{_(x-2,y,1)|_((x+y)*.7,z,.1)|_((x+y+2)*.7,z,.1)|_(x/2+y*.8+1.5,z,.1)}
>contained_by{box{<0,-3,-.1>,<3,0,.1>}}translate z*15finish{ambient 1}}//POV35

Post a reply to this message

Angelo 'kENpEX' Pesce wrote:

> Because I'm sure that maaany intresting shaders will be made if we
> make an easy system to do them. Just check out how many shaders you
> can find for renderman, or how many shader collections there are for
> raytracers that support pluggable shaders (mentalray,lightwave, or mhm
> do U know/remember the essence collection for imagine??). Just think
> about cloud shaders, skin (translucent) shader, special effects,
> cel-look shaders, improved local reflection models... With renderman
> shaders you can even replicate fur...
> Also this is a feature that is not common among freeware raytracers
> (and not so common among commercial raytracers too) so povray could
> make another big step toward being the definitive renderer
> 

By the way, Renderman shaders are much more clear and compact than
many Pov textures (instead of finding contorsions necessary to create a 
given effect, you just code it). In the second edition of the Procedural 
Texures book there are extremely powerful shaders which are shown in
little more than 20/40 lines (and don't tell me you can do everything with
feature X... if this was true, there would be no need for anything besides
assembler!)

If Pov has to have a future, programmable shaders are a must.

Bye!!!
Alessandro Coppo
REM### [at] iolit

Post a reply to this message

On Thu, 6 Dec 2001 13:01:29 -0500, Alessandro Coppo <a.c### [at] iolit>
wrote:

>Angelo 'kENpEX' Pesce wrote:
>
>> Because I'm sure that maaany intresting shaders will be made if we
>> make an easy system to do them. Just check out how many shaders you
>> can find for renderman, or how many shader collections there are for
>> raytracers that support pluggable shaders (mentalray,lightwave, or mhm
>> do U know/remember the essence collection for imagine??). Just think
>> about cloud shaders, skin (translucent) shader, special effects,
>> cel-look shaders, improved local reflection models... With renderman
>> shaders you can even replicate fur...
>> Also this is a feature that is not common among freeware raytracers
>> (and not so common among commercial raytracers too) so povray could
>> make another big step toward being the definitive renderer
>> 
>
>By the way, Renderman shaders are much more clear and compact than
>many Pov textures (instead of finding contorsions necessary to create a 
>given effect, you just code it). In the second edition of the Procedural 
>Texures book there are extremely powerful shaders which are shown in
>little more than 20/40 lines (and don't tell me you can do everything with
>feature X... if this was true, there would be no need for anything besides
>assembler!)
>
>If Pov has to have a future, programmable shaders are a must.
Yeah, I really agree with you... There are even 3d graphicians that do
only shader programming in a 3d production... This should tell us
something about shaders... Btw look just look around and see how many
rman shaders books, examples and neat things are on the web...

Post a reply to this message

>On Thu, 06 Dec 2001 11:21:47 GMT, ken### [at] uniplanit (Angelo 'kENpEX' Pesce) wrote:
>> Mhmm... I think that the raytracer should support those surfaces
>> directly as it's hard for a modeller to do accurate tessellation.
>It could be hard. IMO modellers differ in implementation of patched surfaces,
>nurbs, splines etc.

It could be hard. Many things are hard to do. Shader support is hard
to do. So we can discuss about how to do this instead of if this
should be done... If we agree that it's an interesting feature to add
we can discuss how to do it, if it's doable and other nice things. For
example you're right, they can differ... But since there is a well
accepted standard, we could do them just like renderman does and leave
the trouble to export plugin writers (as there are exporters to
renderman for almost every 3d package, exporting to renderman
style-nurbs is surely possible, so you don't have to care about that)

>> I know if I have only one big nurbs model and an infinite plane, i can
>> use max tessellation and go with this... But if I have a complete,
>> complex scene, with many nurbs characters and a complex background, I
>> don't want to alter manually the tessellation parameters for every
>> object if it's far away or near the camera...
>With POV you are doing everything manually :-)

That's why it takes so much time to set up a scene that it is not used
with commercial modellers while it has all the required rendering
quality to be used... Povray is one of the best raytracers quality
wise, why it should be used only by script-wizards and not by nurbs
modellers too? Why they should always use something else?

>ABX
>--
>#declare _=function(a,b,x){((a^2)+(b^2))^.5-x}#default {pigment{color rgb 1}}
>union{plane{y,-3}plane{-x,-3}finish{reflection 1 ambient 0}}isosurface{ //ABX
>function{_(x-2,y,1)|_((x+y)*.7,z,.1)|_((x+y+2)*.7,z,.1)|_(x/2+y*.8+1.5,z,.1)}
>contained_by{box{<0,-3,-.1>,<3,0,.1>}}translate z*15finish{ambient 1}}//POV35

Post a reply to this message

"Angelo 'kENpEX' Pesce" <ken### [at] uniplanit> wrote in message

ok, for those of us who are just reading this on out - how about using a
couple of paragraphs?? - great blocks of text don't make for easy reading

Thanks


--

Rick

Kitty5 WebDesign - http://Kitty5.com
POV-Ray News & Resources - http://Povray.co.uk
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On Thu, 06 Dec 2001 11:32:00 GMT, ken### [at] uniplanit (Angelo 'kENpEX' Pesce) wrote:
> I'm not depressed at all... But since it's impossible to see a tech
> faq, a document about inner workings, a to-do or a wish list and
> everything seems so "secret" to me, how could I know that those where
> already features somewhat planned or that pov-team was aware of
> them?????

There are very interesting things within sources. Have you read them ? They are
very clear. With programming skills and 3d knowledge they are enough to perform
own patch. They are no secret just like algorithms implemented there. Have you
read faq group on this news server ? There are status reports and other
explanations. Have you read this official faq and Warp's vfaq _befor_ this
discussion ? How many posts have your read _before_ this discussion ? I send my
first post after 50% of this server readed. I send my first wish after 3 years
of playing with POV. And I'm still newbie even if I'm 3d programmer with own
raytracers and own pov-patches. You behave like intruder with your wishes. You
are not asking, you demand. That's why there is my personal objections.

ABX
--
#declare _=function(a,b,x){((a^2)+(b^2))^.5-x}#default {pigment{color rgb 1}}
union{plane{y,-3}plane{-x,-3}finish{reflection 1 ambient 0}}isosurface{ //ABX
function{_(x-2,y,1)|_((x+y)*.7,z,.1)|_((x+y+2)*.7,z,.1)|_(x/2+y*.8+1.5,z,.1)}
contained_by{box{<0,-3,-.1>,<3,0,.1>}}translate z*15finish{ambient 1}}//POV35

Post a reply to this message

In article <3c0f53e6.788389@news.povray.org> , ken### [at] uniplanit (Angelo 
'kENpEX' Pesce) wrote:

> Mhmm... I think that the raytracer should support those surfaces
> directly as it's hard for a modeller to do accurate tessellation. I
> know if I have only one big nurbs model and an infinite plane, i can
> use max tessellation and go with this... But if I have a complete,
> complex scene, with many nurbs characters and a complex background, I
> don't want to alter manually the tessellation parameters for every
> object if it's far away or near the camera...

Ah, so the modeler can't do good tessellation and POV-Ray should magically
be able to do a better job with the same input data?

    Thorsten

Post a reply to this message

<abx### [at] babilonorg> wrote:

>On Thu, 06 Dec 2001 11:32:00 GMT, ken### [at] uniplanit (Angelo 'kENpEX' Pesce) wrote:
>> I'm not depressed at all... But since it's impossible to see a tech
>> faq, a document about inner workings, a to-do or a wish list and
>> everything seems so "secret" to me, how could I know that those where
>> already features somewhat planned or that pov-team was aware of
>> them?????
>
>There are very interesting things within sources. Have you read them ?
A bit

> They are
>very clear. With programming skills and 3d knowledge they are enough to perform
>own patch. They are no secret just like algorithms implemented there.
I know... but U have to figure them out from sources...

> Have you
>read faq group on this news server ?
I have read every faq I found on www.povray.org

> There are status reports and other
>explanations. Have you read this official faq and Warp's vfaq _befor_ this
>discussion ?
Of course

> How many posts have your read _before_ this discussion ? 
Almost everything I found intresting

>I send my
>first post after 50% of this server readed. I send my first wish after 3 years
>of playing with POV. And I'm still newbie even if I'm 3d programmer with own
>raytracers and own pov-patches.
I don't think you're a "newbie" nor I don't think I am. 

> You behave like intruder with your wishes. You
>are not asking, you demand. That's why there is my personal objections.
I really don't think so. I asked where I should post my suggestions
(wish-list) before posting it to warp, after posting if I told that I
was not demanding everything in a very clear way, I explained why I
posted that wishlist, what was my point of view, I think I've always
paied respect to everyone here, to hardcore povray scripters and to
povray developers. If someone has not catched that I'm sorry, mabye I
had to make this more clear. I just wanted to introduce another point
of view, but many people seem only to care about their own. I know
that this ng is made by people that really like writing povscripts
manually and things like that. I *RESPECT* this. But why it's so hard
to understand that mabye there's someone else (not just someone, many
ppl in fact) that need *also* something different?  Why povray should
not take care of them?

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