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Christoph Hormann <chr### [at] gmx de> wrote:
> Subdividing a mesh and displacing in normal direction is not camparable to
> distorting an isosurface function
Why not?
--
#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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In article <3d516e82@news.povray.org>, Warp <war### [at] tag povray org>
wrote:
> > Because I want to have the sides of the HF as well.
>
> Sorry, but I didn't understand this.
The sides of the POV height_field primitive are open, it is just a
sheet. He wants them to be closed, something that I've wanted before too.
It should be possible to get the desired effect using an intersection of
a height field and a box.
--
Christopher James Huff <chr### [at] mac com>
POV-Ray TAG e-mail: chr### [at] tag povray org
TAG web site: http://tag.povray.org/
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Warp wrote:
>
> > Subdividing a mesh and displacing in normal direction is not camparable to
> > distorting an isosurface function
>
> Why not?
>
For example subdividing a mesh can not generate surfaces separated from
the main object.
Christoph
--
POV-Ray tutorials, IsoWood include,
TransSkin and more: http://www.tu-bs.de/~y0013390/
Last updated 03 Aug. 2002 _____./\/^>_*_<^\/\.______
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In article <3D518140.E58214B1@gmx.de>,
Christoph Hormann <chr### [at] gmx de> wrote:
> For example subdividing a mesh can not generate surfaces separated from
> the main object.
That wouldn't exactly be subdividing, but it certainly is a process that
could be done to a mesh.
--
Christopher James Huff <chr### [at] mac com>
POV-Ray TAG e-mail: chr### [at] tag povray org
TAG web site: http://tag.povray.org/
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Christopher James Huff <chr### [at] mac com> wrote:
>> > no trouble with faceting
>>
>> He is using an image to create the heightfield...
> And what does that have to do with faceting?
An image has a limited resolution and thus it will produce faceting.
--
#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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Christopher James Huff <chr### [at] mac com> wrote:
> It should be possible to get the desired effect using an intersection of
> a height field and a box.
Well, do I have to say more?-)
--
#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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Christopher James Huff wrote:
>
> > For example subdividing a mesh can not generate surfaces separated from
> > the main object.
>
> That wouldn't exactly be subdividing, but it certainly is a process that
> could be done to a mesh.
I don't think so (apart from tesselating the isosurface of course)
Christoph
--
POV-Ray tutorials, IsoWood include,
TransSkin and more: http://www.tu-bs.de/~y0013390/
Last updated 03 Aug. 2002 _____./\/^>_*_<^\/\.______
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On Wed, 07 Aug 2002 15:03:21 -0500, Christopher James Huff
<chr### [at] mac com> wrote:
>It should be possible to get the desired effect using an intersection of
>a height field and a box.
I know it _should_ and it works in some cases, but it doesn't always
work. The old trick used was to clip the HF with an open cylinder and
union it with the cylinder clipped by the HF. However, there's no open
box except for an open prism, and that produced artifacts that sturm
didn't fix. It didn't work with clipping or intersecting it with a
regular box either, nor with a semi-open box clipped by a plane.
Do you really think I am _that_ new to POV? :)
It just occurred to me I didn't try intersecting it with a mesh box.
Back to the drawing table.
Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vip bg
TAG e-mail : pet### [at] tag povray org
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In article <3d518426@news.povray.org>, Warp <war### [at] tag povray org>
wrote:
> > And what does that have to do with faceting?
>
> An image has a limited resolution and thus it will produce faceting.
Not on an isosurface. You might get a lumpy appearance from the
interpolation, but not faceting. And that lumpy effect is preferable to
black edges or faceting in some cases.
--
Christopher James Huff <chr### [at] mac com>
POV-Ray TAG e-mail: chr### [at] tag povray org
TAG web site: http://tag.povray.org/
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In article <jp33lu4h4sf8knpgf3l3ltugem5shjpp0i@4ax.com>,
Peter Popov <pet### [at] vip bg> wrote:
> I know it _should_ and it works in some cases, but it doesn't always
> work. The old trick used was to clip the HF with an open cylinder and
> union it with the cylinder clipped by the HF. However, there's no open
> box except for an open prism, and that produced artifacts that sturm
> didn't fix. It didn't work with clipping or intersecting it with a
> regular box either, nor with a semi-open box clipped by a plane.
>
> Do you really think I am _that_ new to POV? :)
>
> It just occurred to me I didn't try intersecting it with a mesh box.
> Back to the drawing table.
I said a box and I meant the built-in "box" primitive.
I just tried it and it works fine. Under what conditions doesn't it
work? Are you making sure the box sides are "inside" the height field?
The artifacts you describe sound like coincident surface problem, or the
box surface being coincident with the height field in/out boundary.
Either use a slightly smaller box or slightly larger height field.
I really wish you could just put "open false" in the height field
block...maybe I'll code that up as a patch someday. It should really
default to on, but having it off by default would preserve backwards
compatibility.
--
Christopher James Huff <chr### [at] mac com>
POV-Ray TAG e-mail: chr### [at] tag povray org
TAG web site: http://tag.povray.org/
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