[x3d-public] HAnimDisplacer effect on coord.point

Sun Feb 9 10:33:35 PST 2025

That would be the point field of a Coordinate node

https://www.web3d.org/specifications/X3Dv4/ISO-IEC19775-1v4-IS/Part01/components/rendering.html#Coordinate

which is used by the coord field of

https://www.web3d.org/specifications/X3Dv4/ISO-IEC19775-1v4-IS/Part01/components/hanim.html#HAnimSegment

Andreas

On Sun, Feb 9, 2025, 12:36 PM Joe D Williams <joedwil at earthlink.net> wrote:

> >  coord node emit a point_changed event
>
>
>
> sorry,I don't see a field anywhere with that event. Displacer is likely to
> change several points when new weight is sent. All part of the cascade to
> produce the changed mesh?
>
> Thanks,
>
> Joe
>
>
>
>
>
> -----Original Message-----
> From: Andreas Plesch <andreasplesch at gmail.com>
> Sent: Feb 9, 2025 4:25 AM
> To: Brutzman, Donald (Don) (CIV) <brutzman at nps.edu>
> Cc: Extensible 3D (X3D) Graphics public discussion <x3d-public at web3d.org>,
> Carol McDonald <cemd2 at comcast.net>, Joe D Williams <joedwil at earthlink.net>,
> John Carlson <yottzumm at gmail.com>
> Subject: Re: [x3d-public] HAnimDisplacer effect on coord.point
>
>
> Don, Joe and John
>
> Thanks for collecting these references.
>
> But I am not sure if there is an answer to my original question. Let me
> rephrase a bit the question:
>
> After a Displacer contained in a Segment node receives a set_weight input,
> should then the coord node emit a point_changed event ?
>
> I do not think HAnim is concerned about that, so it is really a X3D
> question.
>
> Thanks, Andreas
>
> On Sun, Feb 9, 2025, 12:49 AM Brutzman, Donald (Don) (CIV) <
> brutzman at nps.edu> wrote:
>
>> Thanks for pointing in the right direction John.
>>
>> Direct links to functional requirements for Displacer in HAnim 2.0
>> specification:
>>
>>    - HAnim 2.0. Part 1:  Humanoid animation (HAnim) architecture,
>>    Clause 4 Concepts, 4.7 Displacer object
>>    -
>>    https://www.web3d.org/documents/specifications/19774/V2.0/Architecture/concepts.html#DisplacerObject
>>
>>    - HAnim 2.0. Part 1:  Humanoid animation (HAnim) architecture,
>>    Clause 6 Object interfaces, 6.6 Displacer
>>    -
>>    https://www.web3d.org/documents/specifications/19774/V2.0/Architecture/ObjectInterfaces.html#Displacer
>>
>> and
>>
>>    - X3D 4.0 Architecture, Clause 26 Humanoid Animation (HAnim)
>>    component, 26.3.1 HAnimDisplacer
>>    -
>>    https://www.web3d.org/specifications/X3Dv4/ISO-IEC19775-1v4-IS/Part01/components/hanim.html#HAnimDisplacer
>>
>> and informative
>>
>>    - X3D Tooltips, HAnimDisplacer
>>    - https://www.web3d.org/x3d/content/X3dTooltips.html#HAnimDisplacer
>>
>> Thanks for implementation efforts and careful scrutiny.
>>
>> Questions and potential issues/clarifications/corrections are always
>> welcome.
>>
>>
>> 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:* x3d-public <x3d-public-bounces at web3d.org> on behalf of John
>> Carlson via x3d-public <x3d-public at web3d.org>
>> *Sent:* Saturday, February 8, 2025 3:43 AM
>> *To:* Extensible 3D (X3D) Graphics public discussion <
>> x3d-public at web3d.org>; Carol McDonald <cemd2 at comcast.net>; Joe D
>> Williams <joedwil at earthlink.net>
>> *Cc:* John Carlson <yottzumm at gmail.com>; Andreas Plesch <
>> andreasplesch at gmail.com>
>> *Subject:* Re: [x3d-public] HAnimDisplacer effect on coord.point
>>
>> Here’s what HAnim spec says under Displacer:
>>
>> https://www.web3d.org/documents/specifications/19774/V2.0/index.html
>>
>> “For the *Displacer* objects that are contained in the *displacers* field
>> of the *Segment* objects, the *displacements* are defined and applied in
>> the *Segment* coordinate system. The base mesh for the morphed *Segment* is
>> the original mesh defined in the *Segment*.”
>>
>> And here’s what it says under Segment:
>>
>> “
>>
>> The *coord* field is used for *Segment* objects that have deformable
>> meshes and shall contain coordinates referenced from the indexed mesh for
>> the *Segment* object. The coordinates are given the same name as the
>> *Segment* object, but with a "_coords" appended (e.g.,"skull_coords").”
>> displacements are an offset from the mesh,  with weight from 0 to 1.  So
>> weight times displacement is total offset from base mesh.  0 weight = no
>> offset, 1 weight = full displacements offset
>>
>> The Coordinate point is maintained to handle weight = 0.  Weight ranges
>> from 0 to 1, but double check.
>>
>> Joe or Carol might know where to find it in the HAnim spec.
>>
>> I believe the answer is, “during rendering,”. Since weight can vary with
>> animation, and so can displacements, AFAIK.  More than one displacer can be
>> applied to the mesh.
>>
>> I have not read the spec.
>>
>> John
>>
>>
>>
>> On Sat, Feb 8, 2025 at 5:13 AM Andreas Plesch via x3d-public <
>> x3d-public at web3d.org> wrote:
>>
>>
>> https://www.web3d.org/documents/specifications/19775-1/V4.0/Part01/components/hanim.html#HAnimDisplacer
>>
>> does not directly explain what the effect of the displacer on the
>> coord.point field of the containing HAnimSegment is. But it mentions the
>> coord.point field and seems to imply that the coord.point field is involved.
>>
>> So the question is if the Displacer should alter the coord.point field in
>> order to achieve a graphical displacement, or if the Browser should only
>> apply the displacements during rendering without a change in the
>> coord.point field ?
>>
>> This is relevant if the coord.point field is accessed by routes or
>> scripts, in addition to displacers.
>>
>> Thanks for any feedback or ideas,
>>
>> Andreas
>>
>> --
>> Andreas Plesch
>> Waltham, MA 02453
>> _______________________________________________
>> x3d-public mailing list
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>>
>>
>
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