<div dir="auto">I’m imagining there will be changes to C++ SAI. Once new types are in place I can attempt to test. I suggest getting an X3DUOM out soon, so I can regenerate my fieldTypes.js file, which affects all my serializers.</div><div dir="auto"><br></div><div dir="auto">No one is using my serializers that I know of, so this particular change won’t probably affect anyone. They would have to update, and I don’t currently recommend that.</div><div dir="auto"><br></div><div dir="auto">Bug reports are welcome: </div><div dir="auto"><br></div><div dir="auto"><div><a href="https://github.com/coderextreme/X3DJSONLD/issues">https://github.com/coderextreme/X3DJSONLD/issues</a></div><div dir="auto"><br></div><div dir="auto"><br></div>AFAIK, this does not affect X3D JSON, since MFFloat and SFVec4f are represented by arrays.</div><div dir="auto"><br></div><div dir="auto">If you recommend tweaking X3DUOM before your release, I can see what I can do, but it’s not currently a priority for me. Reading the X_ITE component into Blender is higher priority.</div><div dir="auto"><br></div><div dir="auto">Someone speaking up can change the priority.</div><div dir="auto"><br></div><div dir="auto">John</div><div dir="auto"><br><div class="gmail_quote gmail_quote_container" dir="auto"><div dir="ltr" class="gmail_attr">On Wed, Dec 18, 2024 at 6:00 PM Brutzman, Donald (Don) (CIV) via x3d-public <<a href="mailto:x3d-public@web3d.org">x3d-public@web3d.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;padding-left:1ex;border-left-color:rgb(204,204,204)">
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During a specification editors' meeting yesterday, Dick and I made another step forward.</div>
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<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">Mantis 1398: OrthoViewpoint fieldOfView type needs to be SFVec4f, not MFFloat</div>
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<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif"><a href="https://mantis.web3d.org/view.php?id=1398" target="_blank" style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">https://mantis.web3d.org/view.php?id=1398</a></div>
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namely</div>
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<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">If specialty methods for homogeneous transformations (or other operations) are needed by SAI implementations, they can receive specialized definitions to match.</div>
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<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">It is important to remember that (a) no nodes currently use homogenous coordinates, and (b) ClipPlane definition of a half-plane is different than the two parallel-projection extents.</div>
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<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">A graceful approach not requiring implementation changes might be adding prose to Clause 5 field definitions noting alternate usages may occur. For example, appended to the fist sentence, "or other usage of a 4-tuple."</div>
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We applied that change in draft X3D 4.1 Architecture, also committed into git and pushed online.</div>
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<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">5.3.20 SFVec4d and MFVec4d</div>
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<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif"><a href="https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/fieldTypes.html#SFVec4dAndMFVec4d" target="_blank" style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/fieldTypes.html#SFVec4dAndMFVec4d</a></div>
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<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">5.3.21 SFVec4f and MFVec4f</div>
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<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif"><a href="https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/fieldTypes.html#SFVec4fAndMFVec4f" target="_blank" style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/fieldTypes.html#SFVec4fAndMFVec4f</a></div>
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<b style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">5.3.20 SFVec4d and MFVec4d</b></div>
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The SFVec4d field or event specifies a three-dimensional (3D) homogeneous vector<span style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;background-color:rgb(255,255,0)">, or other usage of a 4-tuple</span>. An MFVec4d field or event specifies zero or more
<span style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;background-color:rgb(255,255,0)">SFVec4d values.</span> <span style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;background-color:rgb(255,192,128)"><s style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">3D homogeneous vectors.</s></span> SFVec4d's and MFVec4d's are represented as a 4-tuple of double-precision floating point values
(see 5.3.4 SFDouble and MFDouble). The allowable form for a double-precision floating point number is defined in the specific encoding.</div>
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The default value of an uninitialized SFVec4d field is (0 0 0 1). The default value of an MFVec4d field is the empty list.</div>
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<b style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">5.3.21 SFVec4f and MFVec4f</b></div>
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The SFVec4f field or event specifies a three-dimensional (3D) homogeneous vector<span style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;background-color:rgb(255,255,0)">, or other usage of a 4-tuple</span>. An MFVec4f field or event specifies zero or more
<span style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;background-color:rgb(255,255,0)">SFVec4f values.</span> <span style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;background-color:rgb(255,192,128)"><s style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">3D homogeneous vectors.</s></span> SFVec4f's and MFVec4f's are represented as a 4-tuple of single-precision floating point values
(see 5.3.5 SFFloat and MFFloat). The allowable form for a single-precision floating point number is defined in the specific encoding.</div>
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The default value of an uninitialized SFVec4f field is (0 0 0 1). The default value of an MFVec4f field is the empty list.</div>
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If anyone can think of any reason not to restrict validation of OrthoViewpoint fieldOfView to SFVec4f, instead of an MFFloat array of length 4, please speak up. Am hoping to apply this change next to validation tools next, improving quality assurance and author
confidence that a model is valid. Avoiding run-time errors and maintaining consistency, with no harm to existing X3D models or implementations, is important.</div>
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Have fun with high-quality X3D! 🙂 </div>
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<p style="margin:0in;font-family:Calibri,sans-serif;font-size:11pt"><span style="font-family:"Courier New";font-size:9pt">all the best, Don</span></p>
<p style="margin:0in;font-family:Calibri,sans-serif;font-size:11pt"><span style="font-family:"Courier New";font-size:9pt">--</span></p>
<p style="margin:0in;font-family:Calibri,sans-serif;font-size:11pt"><span style="font-family:"Courier New";font-size:9pt">Don Brutzman Naval Postgraduate School, Code USW/Br <a href="mailto:brutzman@nps.edu" target="_blank" style="font-family:"Courier New"">brutzman@nps.edu</a></span></p>
<p style="margin:0in;font-family:Calibri,sans-serif;font-size:11pt"><span style="font-family:"Courier New";font-size:9pt">Watkins 270, MOVES Institute, Monterey CA 93943-5000 USA +1.831.656.2149</span></p>
<p style="margin:0in;font-family:Calibri,sans-serif;font-size:11pt"><span style="font-family:"Courier New";font-size:9pt">X3D graphics, virtual worlds, navy robotics <a href="https://faculty.nps.edu/brutzman" target="_blank" style="font-family:"Courier New"">https://faculty.nps.edu/brutzman</a></span></p>
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<div id="m_6088885755246314115divRplyFwdMsg" dir="ltr"><span style="font-family:Calibri,sans-serif;font-size:11pt;color:rgb(0,0,0)"><b style="font-family:Calibri,sans-serif">From:</b> Brutzman, Donald (Don) (CIV) <<a href="mailto:brutzman@nps.edu" target="_blank" style="font-family:Calibri,sans-serif">brutzman@nps.edu</a>><br>
<b style="font-family:Calibri,sans-serif">Sent:</b> Friday, December 13, 2024 1:14 PM<br>
<b style="font-family:Calibri,sans-serif">To:</b> Holger Seelig <<a href="mailto:holger.seelig@yahoo.de" target="_blank" style="font-family:Calibri,sans-serif">holger.seelig@yahoo.de</a>>; X3D <<a href="mailto:x3d-public@web3d.org" target="_blank" style="font-family:Calibri,sans-serif">x3d-public@web3d.org</a>><br>
<b style="font-family:Calibri,sans-serif">Cc:</b> <a href="mailto:khyoo@chungbuk.ac.kr" target="_blank" style="font-family:Calibri,sans-serif">khyoo@chungbuk.ac.kr</a> <<a href="mailto:khyoo@chungbuk.ac.kr" target="_blank" style="font-family:Calibri,sans-serif">khyoo@chungbuk.ac.kr</a>>; Myeong Won Lee <<a href="mailto:myeongwonlee@gmail.com" target="_blank" style="font-family:Calibri,sans-serif">myeongwonlee@gmail.com</a>><br>
<b style="font-family:Calibri,sans-serif">Subject:</b> Re: [x3d-public] X3D 4.0 specification problem: TextureProjectorparallel.fieldOfView</span>
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Excellent question, thanks for asking Holger.</div>
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This issue has been carefully tracked and regularly revisited since July 2022.</div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">Mantis 1398: OrthoViewpoint fieldOfView type needs to be SFVec4f, not MFFloat</div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif"><a href="https://mantis.web3d.org/view.php?id=1398" id="m_6088885755246314115OWAa18ba341-198b-8498-7f7c-a8317b5ed604" target="_blank" style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">https://mantis.web3d.org/view.php?id=1398</a></div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">Mantis 1468: must SFVec4f/SFVec4d fields be homogeneous?</div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif"><a href="https://mantis.web3d.org/view.php?id=1468" id="m_6088885755246314115OWA588b0d55-097e-7fd3-585c-a99ae3c02d9a" target="_blank" style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">https://mantis.web3d.org/view.php?id=1468</a></div>
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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.</div>
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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.</div>
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Reviewing the Mantis issues, additional concerns included:</div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif"><i style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">Incompatibility with prior X3D implementations.</i> 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.</div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif"><i style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">SFVec4f fields are actually not homogenous coordinates.</i> The spec uses the word "homogenous" when referring to </div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif"> X3D4 Architecture, Clause 5 Field type reference, 5.3.20 SFVec4d and MFVec4d</div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif"><a href="https://www.web3d.org/specifications/X3Dv4/ISO-IEC19775-1v4-IS/Part01/fieldTypes.html#SFVec4dAndMFVec4d" target="_blank" style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">https://www.web3d.org/specifications/X3Dv4/ISO-IEC19775-1v4-IS/Part01/fieldTypes.html#SFVec4dAndMFVec4d</a></div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">"The SFVec4f field or event specifies a three-dimensional (3D) homogeneous vector." (and similarly for SFVec4d, SFVec4f and MFVec4f).</div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">However none of these fields are mathematically homogeneous, see</div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;color:rgb(51,122,183)"><a href="https://en.wikipedia.org/wiki/Homogeneous_coordinates" target="_blank" style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">https://en.wikipedia.org/wiki/Homogeneous_coordinates</a></div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif"><a href="https://en.wikipedia.org/wiki/Homogeneous_coordinates#/media/File:RationalBezier2D.svg" target="_blank" style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">https://en.wikipedia.org/wiki/Homogeneous_coordinates#/media/File:RationalBezier2D.svg</a></div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">Of related note is that ClipPlane 4-tuple "plane" field is also SFVec4f.</div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif"><a href="https://www.web3d.org/specifications/X3Dv4/ISO-IEC19775-1v4-IS/Part01/components/rendering.html#ClipPlane" target="_blank" style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">https://www.web3d.org/specifications/X3Dv4/ISO-IEC19775-1v4-IS/Part01/components/rendering.html#ClipPlane</a></div>
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All review welcome, hopefully I have correctly synopsized all concerns.</div>
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I think it would be beneficial to resolve this issue by reaching consensus and applying remedies as follow.</div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">Omitting the over-strict word "homogenous" from the four SF/MF Vec 4f/4d definitions in future X3D 4.1 prose,</div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">Updating future X3D 4.1 prose to use SFVec4f for TextureProjectorParallel fieldOfView,</div>
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<div style="direction:ltr;font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif">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.</div>
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Is consensus now possible? Thanks for all careful consideration.</div>
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<p style="margin:0in;font-family:Calibri,sans-serif;font-size:11pt"><span style="font-family:"Courier New";font-size:9pt">all the best, Don</span></p>
<p style="margin:0in;font-family:Calibri,sans-serif;font-size:11pt"><span style="font-family:"Courier New";font-size:9pt">--</span></p>
<p style="margin:0in;font-family:Calibri,sans-serif;font-size:11pt"><span style="font-family:"Courier New";font-size:9pt">Don Brutzman Naval Postgraduate School, Code USW/Br <a href="mailto:brutzman@nps.edu" target="_blank" style="font-family:"Courier New"">brutzman@nps.edu</a></span></p>
<p style="margin:0in;font-family:Calibri,sans-serif;font-size:11pt"><span style="font-family:"Courier New";font-size:9pt">Watkins 270, MOVES Institute, Monterey CA 93943-5000 USA +1.831.656.2149</span></p>
<p style="margin:0in;font-family:Calibri,sans-serif;font-size:11pt"><span style="font-family:"Courier New";font-size:9pt">X3D graphics, virtual worlds, navy robotics <a href="https://faculty.nps.edu/brutzman" target="_blank" style="font-family:"Courier New"">https://faculty.nps.edu/brutzman</a></span></p>
<p style="margin:0in;font-family:Calibri,sans-serif;font-size:11pt"><span style="font-family:"Courier New";font-size:9pt"> </span></p>
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<div dir="ltr" id="m_6088885755246314115x_divRplyFwdMsg"><span style="font-family:Calibri,sans-serif;font-size:11pt;color:rgb(0,0,0)"><b style="font-family:Calibri,sans-serif">From:</b> Holger Seelig <<a href="mailto:holger.seelig@yahoo.de" target="_blank" style="font-family:Calibri,sans-serif">holger.seelig@yahoo.de</a>><br>
<b style="font-family:Calibri,sans-serif">Sent:</b> Friday, December 13, 2024 11:29 AM<br>
<b style="font-family:Calibri,sans-serif">To:</b> X3D <<a href="mailto:x3d-public@web3d.org" target="_blank" style="font-family:Calibri,sans-serif">x3d-public@web3d.org</a>><br>
<b style="font-family:Calibri,sans-serif">Cc:</b> Brutzman, Donald (Don) (CIV) <<a href="mailto:brutzman@nps.edu" target="_blank" style="font-family:Calibri,sans-serif">brutzman@nps.edu</a>>; <a href="mailto:khyoo@chungbuk.ac.kr" target="_blank" style="font-family:Calibri,sans-serif">khyoo@chungbuk.ac.kr</a> <<a href="mailto:khyoo@chungbuk.ac.kr" target="_blank" style="font-family:Calibri,sans-serif">khyoo@chungbuk.ac.kr</a>>; Myeong Won Lee <<a href="mailto:myeongwonlee@gmail.com" target="_blank" style="font-family:Calibri,sans-serif">myeongwonlee@gmail.com</a>><br>
<b style="font-family:Calibri,sans-serif">Subject:</b> Re: [x3d-public] X3D 4.0 specification problem: upVector field for TextureProjector, TextureProjectorParallel</span>
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<div style="direction:ltr">I just realised that TextureProjectorparallel.fieldOfView is of type SFVec4f, but OrthoViewpoint.fieldOfView is of type MFFloat.</div>
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<div style="direction:ltr">Which of the two is better?</div>
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<div style="direction:ltr">OrthoViewpoint is definitely older.</div>
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<div style="direction:ltr">I think of SFVec4f as a mathematical 4d vector.</div>
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<div style="direction:ltr"><a href="https://www.web3d.org/documents/specifications/19775-1/V4.0/Part01/components/textureProjection.html#TextureProjectorParallel" id="m_6088885755246314115OWA1f1dd19a-949b-7455-e7eb-d0a017c40a23" target="_blank">https://www.web3d.org/documents/specifications/19775-1/V4.0/Part01/components/textureProjection.html#TextureProjectorParallel</a></div>
<div style="direction:ltr;color:rgb(0,0,0)"><a href="https://www.web3d.org/documents/specifications/19775-1/V4.0/Part01/components/navigation.html#OrthoViewpoint" id="m_6088885755246314115OWAf7001f8e-7f68-f02d-4500-bf187e8bf1f0" target="_blank">https://www.web3d.org/documents/specifications/19775-1/V4.0/Part01/components/navigation.html#OrthoViewpoint</a></div>
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<div style="direction:ltr">Best regards,</div>
<div style="direction:ltr">Holger</div>
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--</div>
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Holger Seelig</div>
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Leipzig, Germany</div>
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<a href="mailto:holger.seelig@yahoo.de" target="_blank">holger.seelig@yahoo.de</a></div>
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<a href="https://create3000.github.io/x_ite/" target="_blank">https://create3000.github.io/x_ite/</a></div>
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<div style="direction:ltr">Am 08.12.2024 um 05:21 schrieb Brutzman, Donald (Don) (CIV) via x3d-public <<a href="mailto:x3d-public@web3d.org" target="_blank">x3d-public@web3d.org</a>>:</div>
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However</div>
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