[x3d-public] X3D 4.0 specification problem: TextureProjectorparallel.fieldOfView
Andreas Plesch
andreasplesch at gmail.com
Sat Dec 14 12:21:44 PST 2024
There is one, small backwards compatibility issue with going from MFFloat
to SFVec4f which may have not be mentioned. That is the type designation
required for custom fields in Protos (and Scripts) which use
Orthoviewpoint.fieldOfView. But I doubt that there are many examples where
this problem would occur and therefore distract from spec. updates.
Andreas
On Sat, Dec 14, 2024, 12:03 AM <x3d-public-request at web3d.org> wrote:
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> 1. Re: X3D 4.0 specification problem:
> TextureProjectorparallel.fieldOfView (John Carlson)
> 2. Re: X3D 4.0 specification problem:
> TextureProjectorparallel.fieldOfView (joedwil at earthlink.net)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 13 Dec 2024 17:37:58 -0600
> From: John Carlson <yottzumm at gmail.com>
> To: "Extensible 3D (X3D) Graphics public discussion"
> <x3d-public at web3d.org>, Konstantin Smirnov
> <konstantin.e.smirnov at gmail.com>
> Cc: Holger Seelig <holger.seelig at yahoo.de>, "Brutzman, Donald (Don)
> (CIV)" <brutzman at nps.edu>, "khyoo at chungbuk.ac.kr"
> <khyoo at chungbuk.ac.kr>, Myeong Won Lee <myeongwonlee at gmail.com>
> Subject: Re: [x3d-public] X3D 4.0 specification problem:
> TextureProjectorparallel.fieldOfView
> Message-ID:
> <CAGC3UE=OMMvwX62J8A0i+0=
> GgV2kmto9Qy7UAKBdpAYO6FO--g at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> I have no issue with SFVec4f. My only concern is system which require
> field names like x:, y:, z:, ? prior to a number. That would seem
> strange. In that case, MFFloat might be better, or an interval field type,
> which might not participate in many vital events. Konstantin might be a
> good source of information.
>
> Food for thought.
>
> John
>
> On Fri, Dec 13, 2024 at 3:15?PM Brutzman, Donald (Don) (CIV) via x3d-public
> <x3d-public at web3d.org> wrote:
>
> > Excellent question, thanks for asking Holger.
> >
> > This issue has been carefully tracked and regularly revisited since July
> > 2022.
> >
> > - Mantis 1398: OrthoViewpoint fieldOfView type needs to be SFVec4f,
> > not MFFloat
> > - https://mantis.web3d.org/view.php?id=1398
> > - Mantis 1468: must SFVec4f/SFVec4d fields be homogeneous?
> > - https://mantis.web3d.org/view.php?id=1468
> >
> > The X3D Working Group was unable to reach consensus on this issue prior
> to
> > conclusion of version 4.0, unfortunately. Dick Puk and I took a close
> look
> > at this recently too. Here is a synopsis of the Mantis issues.
> >
> > I advocate use of SFVec4f for all parallel fieldOfView values because it
> > is the strictest appropriate datatype that can validate content.
> Retaining
> > the legacy MFFloat type definition for fieldOfView allows 3d models
> > (produced by humans or tools) to define arrays of illegal length, making
> > failures mysterious. Conceptual consistency is important too.
> >
> > Reviewing the Mantis issues, additional concerns included:
> >
> > - *Incompatibility with prior X3D implementations.* Since a 4-tuple
> > content value is a valid MFFloat array, I'm not seeing any backwards
> > incompatibility if a prior X3D 3.3 implementation encounters the four
> > values of a SFVec4f array. There are no representation problems since
> > value syntax is compatible for our various encodings as well.
> >
> > - *SFVec4f fields are actually not homogenous coordinates.* The spec
> > uses the word "homogenous" when referring to
> > - X3D4 Architecture, Clause 5 Field type reference, 5.3.20 SFVec4d
> > and MFVec4d
> > -
> >
> https://www.web3d.org/specifications/X3Dv4/ISO-IEC19775-1v4-IS/Part01/fieldTypes.html#SFVec4dAndMFVec4d
> > - "The SFVec4f field or event specifies a three-dimensional (3D)
> > homogeneous vector." (and similarly for SFVec4d, SFVec4f and
> MFVec4f).
> > - However none of these fields are mathematically homogeneous, see
> > - https://en.wikipedia.org/wiki/Homogeneous_coordinates
> > -
> >
> https://en.wikipedia.org/wiki/Homogeneous_coordinates#/media/File:RationalBezier2D.svg
> > - Of related note is that ClipPlane 4-tuple "plane" field is also
> > SFVec4f.
> > -
> >
> https://www.web3d.org/specifications/X3Dv4/ISO-IEC19775-1v4-IS/Part01/components/rendering.html#ClipPlane
> >
> > All review welcome, hopefully I have correctly synopsized all concerns.
> >
> > I think it would be beneficial to resolve this issue by reaching
> consensus
> > and applying remedies as follow.
> >
> > - Omitting the over-strict word "homogenous" from the four SF/MF Vec
> > 4f/4d definitions in future X3D 4.1 prose,
> > - Updating future X3D 4.1 prose to use SFVec4f for
> > TextureProjectorParallel fieldOfView,
> > - Using SFVec4f in X3D 4.0 DTD, Schema, X3DUOM validation and X3D
> > Tooltips, since that type strictly confirms fieldOfView correctness
> with no
> > backwards compatibility problems.
> >
> > Is consensus now possible? Thanks for all careful consideration.
> >
> > all the best, Don
> >
> > --
> >
> > Don Brutzman Naval Postgraduate School, Code USW/Br
> > brutzman at nps.edu
> >
> > Watkins 270, MOVES Institute, Monterey CA 93943-5000 USA
> > +1.831.656.2149
> >
> > X3D graphics, virtual worlds, navy robotics
> > https://faculty.nps.edu/brutzman
> >
> >
> >
> > ------------------------------
> > *From:* Holger Seelig <holger.seelig at yahoo.de>
> > *Sent:* Friday, December 13, 2024 11:29 AM
> > *To:* X3D <x3d-public at web3d.org>
> > *Cc:* Brutzman, Donald (Don) (CIV) <brutzman at nps.edu>;
> > khyoo at chungbuk.ac.kr <khyoo at chungbuk.ac.kr>; Myeong Won Lee <
> > myeongwonlee at gmail.com>
> > *Subject:* Re: [x3d-public] X3D 4.0 specification problem: upVector field
> > for TextureProjector, TextureProjectorParallel
> >
> > I just realised that TextureProjectorparallel.fieldOfView is of type
> > SFVec4f, but OrthoViewpoint.fieldOfView is of type MFFloat.
> >
> > Which of the two is better?
> >
> > OrthoViewpoint is definitely older.
> >
> > I think of SFVec4f as a mathematical 4d vector.
> >
> >
> >
> https://www.web3d.org/documents/specifications/19775-1/V4.0/Part01/components/textureProjection.html#TextureProjectorParallel
> >
> >
> https://www.web3d.org/documents/specifications/19775-1/V4.0/Part01/components/navigation.html#OrthoViewpoint
> >
> > Best regards,
> > Holger
> >
> > --
> > Holger Seelig
> > Leipzig, Germany
> >
> > holger.seelig at yahoo.de
> > https://create3000.github.io/x_ite/
> >
> > Am 08.12.2024 um 05:21 schrieb Brutzman, Donald (Don) (CIV) via
> x3d-public
> > <x3d-public at web3d.org>:
> >
> > However
> >
> >
> > _______________________________________________
> > x3d-public mailing list
> > x3d-public at web3d.org
> > http://web3d.org/mailman/listinfo/x3d-public_web3d.org
> >
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> ------------------------------
>
> Message: 2
> Date: Sat, 14 Dec 2024 05:02:06 +0000
> From: joedwil at earthlink.net
> To: "Extensible 3D (X3D) Graphics public discussion"
> <x3d-public at web3d.org>, "Extensible 3D (X3D) Graphics public
> discussion" <x3d-public at web3d.org>, Konstantin Smirnov
> <konstantin.e.smirnov at gmail.com>
> Cc: John Carlson <yottzumm at gmail.com>, khyoo at chungbuk.ac.kr, Myeong
> Won Lee <myeongwonlee at gmail.com>
> Subject: Re: [x3d-public] X3D 4.0 specification problem:
> TextureProjectorparallel.fieldOfView
> Message-ID: <79da2843-facc-1fd3-d8bb-be019b6b90a6 at earthlink.net>
> Content-Type: text/plain; charset="utf-8"
>
> Hi,
> I'm just trying to see why the parameters are so different from viewpoint
> and other lights.
>
>
> 17.4.1 DirectionalLight
> SFVec3f [in,out] direction 0 0 -1
> 17.4.3 SpotLight
> SFVec3f [in,out] direction 0 0 -1
> 42.4.1 TextureProjector
> SFVec3f [in,out] direction 0 0 1
> should be default 0 0 -1 toward -z
> (Really should be orientation?)
> SFVec3f [in,out] upVector 0 0 1
> this not needed (see orientation)
> or should be default 0 1 0 (Yup) in Viewpoint coordinate system
> Using like a Viewpoint with headlight as textureprojector but
> viewpoint can be animated independently of textureprojector
> Animating this coordinated with Viewpoint is typical
> TP Needs to use:
> default Viewpoint coordinate system
> (0 0 1 0 = Yup, +x right of viewer, facing -z)
> and orientation navigation using axis-angle,
> Not simple and weaker directon x y z angles
> spotlight movement.
>
> notes:
> 23.4.6 Viewpoint
> SFRotation [in,out] orientation 0 0 1 0 [-1,1],(-8,8)
> SFVec3f [in,out] position 0 0 10 (-8,8)
> 17.4.1 DirectionalLight
> SFVec3f [in,out] direction 0 0 -1 (-8,8)
> 17.4.3 SpotLight
> SFVec3f [in,out] direction 0 0 -1 (-8,8)
> SFVec3f [in,out] location 0 0 0 (-8,8)
> 42.4.1 TextureProjector
> SFVec3f [in,out] direction 0 0 1 (-8,8)
> SFVec3f [in,out] location 0 0 0 (-8,8)
> SFVec3f [in,out] upVector 0 0 1
> (missing (-8,8) notation)
> 18.4.2 MovieTexture
> (nothing)
> Figure 42.5 shows upVector and location
>
> "The direction is the way the perspective projector
> is heading, and this implies to perspective projection
> direction. "
>
> Thanks,
> Joe
>
>
> -----Original Message-----
> From: Extensible 3D (X3D) Graphics public discussion <x3d-public at web3d.org
> >
> Sent: Dec 13, 2024 3:39 PM
> To: Extensible 3D (X3D) Graphics public discussion <x3d-public at web3d.org>,
> Konstantin Smirnov <konstantin.e.smirnov at gmail.com>
> Cc: John Carlson <yottzumm at gmail.com>, khyoo at chungbuk.ac.kr <
> khyoo at chungbuk.ac.kr>, Myeong Won Lee <myeongwonlee at gmail.com>
> Subject: Re: [x3d-public] X3D 4.0 specification problem:
> TextureProjectorparallel.fieldOfView
>
> I have no issue with SFVec4f. My only concern is system which require
> field names like x:, y:, z:, … prior to a number. That would seem
> strange. In that case, MFFloat might be better, or an interval field type,
> which might not participate in many vital events. Konstantin might be a
> good source of information.
>
> Food for thought.
>
>
> John
>
> On Fri, Dec 13, 2024 at 3:15?PM Brutzman, Donald (Don) (CIV) via
> x3d-public <x3d-public at web3d.org (mailto:x3d-public at web3d.org)> wrote:
> Excellent question, thanks for asking Holger.
>
> This issue has been carefully tracked and regularly revisited since July
> 2022.
> * Mantis 1398: OrthoViewpoint fieldOfView type needs to be SFVec4f, not
> MFFloat
>
> * https://mantis.web3d.org/view.php?id=1398
>
> * Mantis 1468: must SFVec4f/SFVec4d fields be homogeneous?
>
> * https://mantis.web3d.org/view.php?id=1468
>
>
> The X3D Working Group was unable to reach consensus on this issue prior to
> conclusion of version 4.0, unfortunately. Dick Puk and I took a close look
> at this recently too. Here is a synopsis of the Mantis issues.
>
> I advocate use of SFVec4f for all parallel fieldOfView values because it
> is the strictest appropriate datatype that can validate content. Retaining
> the legacy MFFloat type definition for fieldOfView allows 3d models
> (produced by humans or tools) to define arrays of illegal length, making
> failures mysterious. Conceptual consistency is important too.
>
> Reviewing the Mantis issues, additional concerns included:
> * Incompatibility with prior X3D implementations. Since a 4-tuple
> content value is a valid MFFloat array, I'm not seeing any backwards
> incompatibility if a prior X3D 3.3 implementation encounters the four
> values of a SFVec4f array. There are no representation problems since
> value syntax is compatible for our various encodings as well.
>
>
>
> * SFVec4f fields are actually not homogenous coordinates. The spec
> uses the word "homogenous" when referring to
>
> * X3D4 Architecture, Clause 5 Field type reference, 5.3.20 SFVec4d and
> MFVec4d
>
> *
> https://www.web3d.org/specifications/X3Dv4/ISO-IEC19775-1v4-IS/Part01/fieldTypes.html#SFVec4dAndMFVec4d
>
> * "The SFVec4f field or event specifies a three-dimensional (3D)
> homogeneous vector." (and similarly for SFVec4d, SFVec4f and MFVec4f).
>
> * However none of these fields are mathematically homogeneous, see
>
> * https://en.wikipedia.org/wiki/Homogeneous_coordinates
>
> *
> https://en.wikipedia.org/wiki/Homogeneous_coordinates#/media/File:RationalBezier2D.svg
>
> * Of related note is that ClipPlane 4-tuple "plane" field is also
> SFVec4f.
>
> *
> https://www.web3d.org/specifications/X3Dv4/ISO-IEC19775-1v4-IS/Part01/components/rendering.html#ClipPlane
>
>
>
> All review welcome, hopefully I have correctly synopsized all concerns.
>
> I think it would be beneficial to resolve this issue by reaching consensus
> and applying remedies as follow.
> * Omitting the over-strict word "homogenous" from the four SF/MF Vec
> 4f/4d definitions in future X3D 4.1 prose,
>
> * Updating future X3D 4.1 prose to use SFVec4f for
> TextureProjectorParallel fieldOfView,
>
> * Using SFVec4f in X3D 4.0 DTD, Schema, X3DUOM validation and X3D
> Tooltips, since that type strictly confirms fieldOfView correctness with no
> backwards compatibility problems.
>
>
> Is consensus now possible? Thanks for all careful consideration.
>
> all the best, Don
> --
> Don Brutzman Naval Postgraduate School, Code USW/Br
> brutzman at nps.edu (mailto:brutzman at nps.edu)
> Watkins 270, MOVES Institute, Monterey CA 93943-5000 USA
> +1.831.656.2149
> X3D graphics, virtual worlds, navy robotics
> https://faculty.nps.edu/brutzman
>
>
>
>
> From: Holger Seelig <holger.seelig at yahoo.de (mailto:holger.seelig at yahoo.de
> )>
> Sent: Friday, December 13, 2024 11:29 AM
> To: X3D <x3d-public at web3d.org (mailto:x3d-public at web3d.org)>
> Cc: Brutzman, Donald (Don) (CIV) <brutzman at nps.edu (mailto:
> brutzman at nps.edu)>; khyoo at chungbuk.ac.kr (mailto:khyoo at chungbuk.ac.kr) <
> khyoo at chungbuk.ac.kr (mailto:khyoo at chungbuk.ac.kr)>; Myeong Won Lee <
> myeongwonlee at gmail.com (mailto:myeongwonlee at gmail.com)>
> Subject: Re: [x3d-public] X3D 4.0 specification problem: upVector field
> for TextureProjector, TextureProjectorParallel
>
> I just realised that TextureProjectorparallel.fieldOfView is of type
> SFVec4f, but OrthoViewpoint.fieldOfView is of type MFFloat.
>
> Which of the two is better?
>
> OrthoViewpoint is definitely older.
>
> I think of SFVec4f as a mathematical 4d vector.
>
>
> https://www.web3d.org/documents/specifications/19775-1/V4.0/Part01/components/textureProjection.html#TextureProjectorParallel
>
> https://www.web3d.org/documents/specifications/19775-1/V4.0/Part01/components/navigation.html#OrthoViewpoint
>
> Best regards,
> Holger
>
> --
> Holger Seelig
> Leipzig, Germany
>
> holger.seelig at yahoo.de (mailto:holger.seelig at yahoo.de)
> https://create3000.github.io/x_ite/
>
> Am 08.12.2024 um 05:21 schrieb Brutzman, Donald (Don) (CIV) via x3d-public
> <x3d-public at web3d.org (mailto:x3d-public at web3d.org)>:
>
> However
>
> _______________________________________________
> x3d-public mailing list
> x3d-public at web3d.org (mailto:x3d-public at web3d.org)
> http://web3d.org/mailman/listinfo/x3d-public_web3d.org
>
>
>
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