In article <3C70EA64.D2E842C9@atosorigin.com>,


> I'm wondering about the possible tesselation of Pov object: 
> 
> would you expect the textures of the tesselated object to be taken in the 
> generated mesh ?
> Or would you only expect to get the form with only the default texture ?
> Or something else ?

I don't see a reason for an object rendered using tesselation to have a 
different texture. I'm assuming tesselation is done as an object option 
though, not as generating a new object.


> Should the actual texture be used?
>  or sampled at the triangle vertex, keeping only a RGB(TF) vector ?

The actual texture. Vertex coloring would require a high-resolution mesh 
just for proper texturing, but that won't work for some objects (for 
example, a box can be tesselated with just 12 triangles, and a plane 
with 2, and a triangle with 1).

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

Post a reply to this message

Christopher James Huff wrote:
> 
> In article <3C70EA64.D2E842C9@atosorigin.com>,

> 
> > I'm wondering about the possible tesselation of Pov object:
> >
> > would you expect the textures of the tesselated object to be taken in the
> > generated mesh ?
> > Or would you only expect to get the form with only the default texture ?
> > Or something else ?
> 
> I don't see a reason for an object rendered using tesselation to have a
> different texture. I'm assuming tesselation is done as an object option
> though, not as generating a new object.

I think that it would be a great pity if
a POV-patch were to perform tessellation
of an object without providing the possi-
bility to texture different copies of it
differently.


Tor Olav

Post a reply to this message

In article <3C7### [at] onlineno>,
 Tor Olav Kristensen <tor### [at] onlineno> wrote:

> I think that it would be a great pity if
> a POV-patch were to perform tessellation
> of an object without providing the possi-
> bility to texture different copies of it
> differently.

I wasn't talking about copies, but an alternate rendering method. A 
"tesselate" flag that would cause the object to be tesselated and 
rendered (and traced) as a mesh. Copies would be textured the same way 
any other object copies are textured.

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

Post a reply to this message

Christopher James Huff wrote:

> I wasn't talking about copies, but an alternate rendering method. A
> "tesselate" flag that would cause the object to be tesselated and
> rendered (and traced) as a mesh. Copies would be textured the same way
> any other object copies are textured.

Well, I wasn't talking about tesselating for rendering but mainly to
get an mesh object. What is done with the mesh is then upto the user.
It would be rendered at the end, but also may be in the meantime some non-linear
transformation might be performed on it.
Or thousand of copies of the mesh made, instead of thousand of copies of
some memory consuming objects.
Or whatever the user wants.

The main objective I want to stick with is: 
One object (which might be very complex, but it is bounded, finite and solid) is
provided,
you get back a closed mesh which is somehow similar to the provided object.

I do not want to make any change in the rendering engine.
I do not want to provide a global setting which would tesselate all objects in a scene
before rendering the tesselated set of objects.

It's just a kind of 'avoid the modeler & parsing time of mesh files'.

-- 
Non Sine Numine
http://grimbert.cjb.net/
Puis, s'il advient d'un peu triompher, par hasard,

Post a reply to this message

> Sort of, I currently have 6 differents ways to tesselate an object:
>  2 based on marching tetrahedrons, using intersection test (IIRC);
>  4 based on marching cube, using insideness and various way to do the
triangles;
>  (but for the latest 2, I still need to check the PD aspect of the
tesselation,
>  because what I can do ok in my kitchen might not be ok in exported code.)
>
> All workings fine with sphere/box/cone/cylinder/torus, but still need to
check
> with more fancy objects (such as julia_fractal, blob, CSG and so on...).

have you considered assigning standard pov objects (eg sphere) a pre defined
mesh, marching for all non regular objects (such as blobs) then deal with
csg


--

Rick

Kitty5 WebDesign - http://Kitty5.com
POV-Ray News & Resources - http://Povray.co.uk
TEL : +44 (01270) 501101 - FAX : +44 (01270) 251105 - ICQ : 15776037

PGP Public Key
http://pgpkeys.mit.edu:11371/pks/lookup?op=get&search=0x231E1CEA

Post a reply to this message

"Rick [Kitty5]" wrote:
> have you considered assigning standard pov objects (eg sphere) a pre defined
> mesh, marching for all non regular objects (such as blobs) then deal with
> csg

Sorry to sound offensive but:
<Irony on>
 Please do the same for UV-Mapping first, 
then I will slaveshly copy your solution to perform tesselation.
Afterall, UV mapping is present in megapov since so much time...
<Irony off>
Just think about both problem, they are very similar.

To reassure you, I should post soon a tesselation of a sphere in p.b.i.
(Low resolution of tessel, unsmoothed mesh). How many slice do you want ?
Do you have any other fetish object that you (or someone else) would like
to see tesselated ? (you provide the code or the pointer to it !)

P.S.: To really answer your question, Yes I did, and I consider it was
not forth it (adding pre-tesselated primitive) as long as the marching
variant were able to provide a good result. And most mesh are not simple
primitive anyway. With the marching approach, I have a hammer, so everything
is going to be a nail !
(But I have different hammers (6), not just one big universal one...)
-- 
Non Sine Numine
http://grimbert.cjb.net/
Puis, s'il advient d'un peu triompher, par hasard,

Post a reply to this message

<jer### [at] atosorigincom> wrote:
> Do you have any other fetish object that you (or someone else) would like
> to see tesselated ?

new povlogo

it's realy is good testing object: cone, sphere, difference, union,
translations, rotations, splitted volume, sharp edges, smooth surface

ABX

Post a reply to this message

news:3C7248A9.A515605B@atosorigin.com...

> To reassure you, I should post soon a tesselation of a sphere in p.b.i.
> (Low resolution of tessel, unsmoothed mesh). How many slice do you want ?
> Do you have any other fetish object that you (or someone else) would like
> to see tesselated ? (you provide the code or the pointer to it !)
>

My car =)

http://news.povray.org/povray.binaries.scene-files/22093/150317/NekCar_F15.pov
http://news.povray.org/povray.binaries.scene-files/22093/150317/Car_F15.inc

I wonder how long it would take to tessellate it...

--
#local X=20*<-2,2,5>;#local K=2*z*X-X;#local R=seed(frame_number);blob{#while(K
.x>X.x)#local N=X+<rand(R)rand(R)1>/3;#local X=(vlength(N-K)<vlength(X-K)?N:2*X
-N);sphere{X,1,1rotate z*90}sphere{X,1,1}#end pigment{rgbt 1}interior{media{
emission<2,4,5>*5}}hollow scale.05}//   http://nekar_xenos.tripod.com/metanoia/
sphere_sweep{catmull_rom_spline 6<-8,-8>1<-8,-8>1<-8,8>1<8,-8>1<8,8>1<8,8>1
translate 20*z pigment{gradient z scale 3color_map{[0rgb<0,9,18>][1rgb 0]}}}


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.324 / Virus Database: 181 - Release Date: 2002/02/14

Post a reply to this message

Nekar Xenos wrote:
> My car =)
> ...

You and that car... I think you're obssessed ;)

-- 
signature{
  "Grey Knight" contact{ email "gre### [at] yahoocom" }
  site_of_week{ url "http://digilander.iol.it/jrgpov" }
}

Post a reply to this message

None of that would be a problem.
This is what I'm thinking:

1: A "tesselate" flag for each shape. Some shapes (simple ones like 
spheres, cylinders, boxes, triangles, polygons, meshes, height 
fields...) will have specialized tesselation methods, the rest will use 
the generic methods. I actually got most of the work on this done using 
Warp's tesselation code, but never finished it.
When the tesselate flag is specified, the object is tesselated. Copies 
of it share the same mesh data, unless tesselation is specified for the 
copy, in which case it gets its own mesh (useful if you want multiple 
copies with different tesselation parameters). The resulting object uses 
the mesh for intersection calculations, but the original insideness 
calculations, so it is still useful for CSG.

2: Objects can be used in a mesh statement. The object is then 
tesselated and the resulting triangles placed in the mesh. The 
"tesselate" flag is used to give any special settings to the tesselation 
code, if not specified the defaults are used.

3: Possibly, allow non-linear deformations for all shapes. Those shapes 
that don't support a more direct method will tesselate and deform the 
mesh.

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

Post a reply to this message