[x3d-public] Displacer and normals ?

Sat Feb 15 13:34:13 PST 2025

Non-linear displacement paths

>
> It would be probably feasible from an implementation perspective to have
> displacers with weight (key) ranges for piecewise linear interpolations to
> approximate curved displacement paths. Thinking about it, it may already be
> possible to design a CoordinateInterpolator of _displacement_ keyValues
> which gets routed to the displacement field of a displacer, with a constant
> weight of 1. So animation then happens by changing displacement values
> directly rather than weight values. This would allow for arbitrary
> displacement paths and does not need any changes, still allowing targeting
> vertex subsets and composing. Might be worth testing, seems interesting.
>

This idea seems to work. Here is a simple example based on John's Tongue.x3d

https://raw.githubusercontent.com/andreasplesch/x3dom/refs/heads/HAnim_displacers/test/functional/hanim/tongueCurved.x3d
[ Use Alt-Q to flip line wrapping of long lines. ]

It adds an additional displacement step halfways through the animation
which has non-linear z displacements.

Could be interesting.

-Andreas

-Andreas
>
> On Wed, Feb 12, 2025 at 10:58 PM Joe D Williams <joedwil at earthlink.net>
> wrote:
>
>> I think degenerate triangles, ones that flip from ccw to cw, or overlap or
>>
>> whatever messes up a triangle when any of all of its points get moved
>>
>> is purely result of author error(s) in setting the parameter(s).
>>
>>
>>
>> Whatever happens with normals of triangles moved or destroyed by Displacer
>>
>> must match what happens with points moved by joint-driven skin animations
>>
>> which can also mess up, and by points moved by CoordinateInterpolator,
>>
>> same as any morphing operation.
>>
>> Normals can also be set by the author each frame if desired.
>>
>>
>>
>> Maybe some help given in authortime but not any sort of
>>
>> enumerated error except undefined in runtime since this visual effect;
>>
>> it is just an artifact of bad data.
>>
>> Esp likey when deformable face is actually composed of multiple shapes
>>
>> and they must blend regardless of the combinations of shapes
>>
>> that move to make the motion for a pose.
>>
>> Always? much easier with single basic mesh for the face and and then
>>
>> add features and accessories animated individually?
>>
>>
>>
>> One of the limitations with Displacer is that it is just a single scaled
>> 3D vector,
>>
>> meaning it has a fixed relative direction regardless of the weight
>> applied.
>>
>> When a curved displacement is required, then point motion can be
>>
>> controlled using joint rotation, like the eyeball.
>>
>> In some cases,a CoordinateInterpolator may be used to move points
>> around.
>>
>> Texture position and rotation can be animated.
>>
>>
>>
>> Since all these Displacer nodes have been produced by finding the
>>
>> simple 3D vector difference between the first and last data point
>>
>> of a source CoordinateInterpolator it is likely that some displacements
>>
>> do not produce exact same movement of a point just because the
>>
>> original interpolator keyValue keyframe data points described a curved
>> path.
>>
>>
>>
>> Sure, we can update the 3D vector direction each frame if we want to,
>>
>> but I would like to see a Displacer which could use multiple sets of
>> vectors
>>
>> interpolated to produce computed keyframes like other interpolators.
>>
>> For each point there could be a set of vectors where the output value for
>>
>> point movement is the result of interpolation between
>>
>> adjacent key time (weight) keyValue 3D vectors.
>>
>>
>>
>> So, more fun with x3d HAnim
>>
>> Thanks,
>>
>> Joe
>>
>>
>>
>>
>>
>> -----Original Message-----
>> From: Extensible 3D (X3D) Graphics public discussion <
>> x3d-public at web3d.org>
>> Sent: Feb 12, 2025 9:11 AM
>> To: X3D Graphics public mailing list <x3d-public at web3d.org>
>> Cc: Andreas Plesch <andreasplesch at gmail.com>
>> Subject: Re: [x3d-public] Displacer and normals ?
>>
>>
>>
>> Responses below:
>>
>>
>>> Date: Tue, 11 Feb 2025 15:58:40 -0600
>>> From: John Carlson <yottzumm at gmail.com>
>>> To: "Extensible 3D (X3D) Graphics public discussion"
>>>         <x3d-public at web3d.org>
>>> Subject: Re: [x3d-public] Displacer and normals ?
>>>
>>> Did you get the black tongue effect?  I?ve seen that in Sunrize, and
>>> reported it there.  Holger had a response about providing normals.
>>
>>
>> I found https://github.com/create3000/sunrize/issues/9
>>
>> Yes, I think this is similar. x-ite/sunrize just may not automatically
>> recalculate normals for performance reasons which in some cases may be
>> beneficial by avoiding the effects of degenerate triangles.
>>
>>
>>> The displacers were taken from CoordinateInterpolators in the
>>> HumanoidAnimation/FacialAnimation X3D archive.
>>>
>>> https://www.web3d.org/x3d/content/examples/HumanoidAnimation/FacialAnimation/index.html
>>> Perhaps we could derive normals from those examples, realizing only one
>>> set
>>> of meshes is chosen for the final version.
>>>
>>> It?s relevant, because I will be providing a unified skin mesh for FACS,
>>> and it would be nice to provide normals.
>>
>>
>> I noticed the effect actually only in combined displacers/morphers, eg.
>> the Contempt combo. That brings up the future question of how pre-computed
>> normals from multiple displacers may be combined, maybe just by averaging
>> the slerped orientation from each.
>> There may have been studies on how to best recombine facial
>> subexpressions for a valid result.
>>
>> -Andreas
>>
>>
>>>
>>> On Tue, Feb 11, 2025 at 3:41?PM Andreas Plesch via x3d-public <
>>> x3d-public at web3d.org> wrote:
>>>
>>> > I noticed that some displacers cause degenerate or flipped triangles
>>> which
>>> > may cause rendering problems, mostly due to problems calculating
>>> > automatically a good normal vector.
>>> >
>>> > In general, for best rendering results, it is necessary to provide
>>> > precomputed normals. rather than rely on automatic normal
>>> calculations. Was
>>> > there a discussion on how to have displacers provide precomputed
>>> normals
>>> > along with the displacement of the vertices ? That  would help with
>>> > rendering quality, and may be necessary for some use cases.
>>> >
>>> > This may be deemed a long term feature to consider.
>>> >
>>> > Perhaps an idea would be a MFRotation normalRotations field which has
>>> the
>>> > rotation required to rotate the normal (per vertex, or perhaps per
>>> face)
>>> > from the rest orientation to the final orientation. Weights are applied
>>> > with slerp. For animation authors it would be probably easier to be
>>> able to
>>> > just directly provide the final orientation.
>>> >
>>> > Any feedback or comment much welcome, -Andreas
>>> >
>>> >
>>> > --
>>> > Andreas Plesch
>>> > Waltham, MA 02453
>>> > _______________________________________________
>>> > x3d-public mailing list
>>> > x3d-public at web3d.org
>>> > http://web3d.org/mailman/listinfo/x3d-public_web3d.org
>>> >
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>>> ------------------------------
>>>
>>> Message: 3
>>> Date: Wed, 12 Feb 2025 11:27:59 -0500
>>> From: Andreas Plesch <andreasplesch at gmail.com>
>>> To: John Carlson <yottzumm at gmail.com>
>>> Cc: Holger Seelig <holger.seelig at yahoo.de>,  X3D Graphics public
>>>         mailing list <x3d-public at web3d.org>, Joe D Williams
>>>         <joedwil at earthlink.net>
>>> Subject: Re: [x3d-public] Turning on and off simultaneous animations
>>>         individually
>>> Message-ID:
>>>         <
>>> CAKdk67vXRSz1pM4QLjcxuCQHfjY4LUT924cSmX7rPAasroPUCw at mail.gmail.com>
>>> Content-Type: text/plain; charset="utf-8"
>>>
>>> Hi,
>>>
>>> I took a first stab at Displacers in Segments for x3dom and use it now in
>>> the editor:
>>>
>>>
>>> https://andreasplesch.github.io/Library/Viewer/index.html?url=https://raw.githubusercontent.com/coderextreme/ci2had/refs/heads/main/resources/ManyClocks.x3d
>>>
>>> This is experimental and mostly for testing purposes. If there is an
>>> example combining Displacers in both Joints and Segments that would be
>>> interesting as it is not necessarily expected to work.
>>> The experimental implementation is inefficient and expensive as it is
>>> weight_changed event driven. If you activate multiple displacers the
>>> frame
>>> rate starts to drop. It probably is not very useful at this point.
>>>
>>> Fee free to give it a try, -Andreas
>>>
>>> On Wed, Feb 5, 2025, 4:11?PM Andreas Plesch <andreasplesch at gmail.com>
>>> wrote:
>>>
>>> > Hi John,
>>> >
>>> > Thanks. I found the tongue.x3d example but if you can create another
>>> one
>>> > that would be helpful in general.
>>> >
>>> > You vastly overestimate my ability and availability ;) This would be a
>>> > longer term project. I have an idea what to do.
>>> >
>>> > Andreas
>>> >
>>> >
>>> > On Wed, Feb 5, 2025, 1:31?PM John Carlson <yottzumm at gmail.com> wrote:
>>> >
>>> >> I had one I sent to Holger, probably derived from this one:
>>> >>
>>> >>
>>> >>
>>> https://github.com/coderextreme/ci2had/blob/main/resources/JinMouthStretch.x3d
>>> >>
>>> >>
>>> >> What I would do (again) is take out all the segments but the tongue.
>>> >>
>>> >> There?s no menus involved in this one.
>>> >>
>>> >> If you need further assistance, like a smaller example, I can help.
>>> Also
>>> >> all the Jin*.x3d FACS action units can also provide examples.
>>> >>
>>> >> I?ll be pretty unbusy today.  I can allocate some time for creating a
>>> >> model, make sure it animates, etc.
>>> >>
>>> >> If you?re able to allocate some time today, great, we have an HAnim
>>> >> meeting tomorrow and showing off X3DOM editor using Displacers would
>>> be
>>> >> fantastic!
>>> >>
>>> >> Remember there?s a coord field in HAnimSegment that the HAnimDisplacer
>>> >> operates on!
>>> >>
>>> >> John
>>> >>
>>> >> On Wed, Feb 5, 2025 at 12:01?PM Andreas Plesch <
>>> andreasplesch at gmail.com>
>>> >> wrote:
>>> >>
>>> >>> Hi John,
>>> >>>
>>> >>> The reason is that Displacers are currently implemented in x3dom only
>>> >>> for Joints, but not for Segments, unfortunately. Do you know of a
>>> simple
>>> >>> but instructive test case of Segments with Displacers ?
>>> >>>
>>> >>> Andreas
>>> >>>
>>> >>>
>>> >>> On Tue, Feb 4, 2025, 2:33?PM John Carlson <yottzumm at gmail.com>
>>> wrote:
>>> >>>
>>> >>>> I will try to test this in castle model converter.
>>> >>>>
>>> >>>> I did try setting a value for the outputOnly fields, but the
>>> converter
>>> >>>> wouldn?t shut up.
>>> >>>>
>>> >>>> The model below doesn?t seem to animate when one presses the menu
>>> >>>> items.  Did you get it to animate?
>>> >>>>
>>> >>>> On Tue, Feb 4, 2025 at 12:27?PM Andreas Plesch <
>>> andreasplesch at gmail.com>
>>> >>>> wrote:
>>> >>>>
>>> >>>>> Hi John, all,
>>> >>>>>
>>> >>>>> It turns out that x3dom currently expects a default value for Proto
>>> >>>>> fields even for outputOnly fields. This is due to how Proto fields
>>> are
>>> >>>>> initialized. They always need to have a value. While the spec.
>>> does not
>>> >>>>> require this, it seems still good practice to always define a
>>> default value
>>> >>>>> in the ProtoInterface. There may be a case where an outputOnly
>>> field is
>>> >>>>> used in ISing where a valid value would be expected. There may be
>>> other
>>> >>>>> corner cases.
>>> >>>>>
>>> >>>>> Here is your example with added default values for outputOnly
>>> fields:
>>> >>>>>
>>> >>>>>
>>> >>>>>
>>> https://andreasplesch.github.io/Library/Viewer/index.html?url=https://gist.githubusercontent.com/andreasplesch/af5ff3148c1159f71d34fb78c1f63024/raw/b3d4470107ab74e301ed48448ab2a4f4154672e0/ManyClocks_John.x3d
>>> >>>>>
>>> >>>>> This could be fixed in x3dom, by always setting some default
>>> value. Is
>>> >>>>> there a list of recommended defaults for each data type if no
>>> other source
>>> >>>>> of defaults is available? For SFTime it seems to be -1.
>>> >>>>>
>>> >>>>>
>>> >>>>> -Andreas
>>> >>>>>
>>> >>>>>
>>> >>>>> On Mon, Feb 3, 2025 at 7:39?AM Andreas Plesch <
>>> andreasplesch at gmail.com>
>>> >>>>> wrote:
>>> >>>>>
>>> >>>>>> Hi John,
>>> >>>>>>
>>> >>>>>> On Mon, Feb 3, 2025 at 12:48?AM John Carlson <yottzumm at gmail.com>
>>> >>>>>> wrote:
>>> >>>>>>
>>> >>>>>>> Andreas, "startTime" is an accessType outputOnly field, so why
>>> do I
>>> >>>>>>> need to provide a value attribute in fieldValue?  I'm kind of
>>> confused.
>>> >>>>>>> I'm probably missing something in the spec.
>>> >>>>>>>
>>> >>>>>>
>>> >>>>>> You are right, I only outlined scenarios where the accessType
>>> allows
>>> >>>>>> input or initialization..
>>> >>>>>> In the outputOnly case it is not necessary to provide a fieldValue
>>> >>>>>> node at all since there is no value which can be provided.
>>> Providing the
>>> >>>>>> node would indeed be confusing, to both the user code reader and
>>> any X3D
>>> >>>>>> browser.
>>> >>>>>> I believe the spec. is silent on this case in any encoding.
>>> >>>>>>
>>> >>>>>> Best, Andreas
>>> >>>>>>
>>> >>>>>> Thanks for any clarification.
>>> >>>>>>>
>>> >>>>>>> I have finally enabled schematron on the project, but I'm
>>> finding it
>>> >>>>>>> hard to understand the messages, and modifications that I make,
>>> while
>>> >>>>>>> removing the immediate problems, seem to move the problems
>>> elsewhere.
>>> >>>>>>>
>>> >>>>>>> Explaining why I need a "startTime" fieldValue value is my main
>>> lack
>>> >>>>>>> of understanding, but perhaps I need a whole review of
>>> accessType.
>>> >>>>>>>
>>> >>>>>>> Castle Model Converter reports:
>>> >>>>>>>
>>> >>>>>>> castle-model-converter: Warning: X3D: X3D XML: <fieldValue>
>>> element
>>> >>>>>>> references unknown field name "enabled"
>>> >>>>>>> castle-model-converter: Warning: X3D: X3D XML: <fieldValue>
>>> element
>>> >>>>>>> references unknown field name "startTime"
>>> >>>>>>> castle-model-converter: Warning: X3D: X3D XML: <fieldValue>
>>> element
>>> >>>>>>> references unknown field name "stopTime"
>>> >>>>>>>
>>> >>>>>>> I will try providing a field value in the ProtoInterface
>>> >>>>>>>
>>> >>>>>>> If I "cleanup" enabled, startTime and stopTime, I get:
>>> >>>>>>>
>>> >>>>>>> castle-model-converter: Warning: VRML/X3D: Within prototype
>>> >>>>>>> "MenuItem", event "inputTrue" references (by "IS" clause)
>>> non-existing
>>> >>>>>>> event "enabled"
>>> >>>>>>> castle-model-converter: Warning: VRML/X3D: Within prototype
>>> >>>>>>> "MenuItem", event "triggerTime" references (by "IS" clause)
>>> non-existing
>>> >>>>>>> event "startTime"
>>> >>>>>>> castle-model-converter: Warning: VRML/X3D: Within prototype
>>> >>>>>>> "MenuItem", event "triggerTime" references (by "IS" clause)
>>> non-existing
>>> >>>>>>> event "stopTime"
>>> >>>>>>>
>>> >>>>>>> I guess what I conclude at this point is, startTime and stopTime
>>> are
>>> >>>>>>> bad DEF names, but what about enabled as a field?  The dominoes
>>> are falling.
>>> >>>>>>>
>>> >>>>>>> About your two scenarios in the other message, perhaps this is
>>> >>>>>>> revealing.
>>> >>>>>>>
>>> >>>>>>> See attached attempt to fix original issue, which resulted in the
>>> >>>>>>> above.
>>> >>>>>>>
>>> >>>>>>> John
>>> >>>>>>>
>>> >>>>>>> On Sun, Feb 2, 2025 at 3:59?PM Andreas Plesch <
>>> >>>>>>> andreasplesch at gmail.com> wrote:
>>> >>>>>>>
>>> >>>>>>>> I think x3dom, reasonably, expects a value for the fieldValue
>>> nodes:
>>> >>>>>>>>
>>> >>>>>>>> For example:
>>> >>>>>>>>
>>> >>>>>>>> <fieldValue name="startTime" />
>>> >>>>>>>>
>>> >>>>>>>> and others.
>>> >>>>>>>>
>>> >>>>>>>> On Sun, Feb 2, 2025 at 5:42?AM John Carlson <yottzumm at gmail.com
>>> >
>>> >>>>>>>> wrote:
>>> >>>>>>>>
>>> >>>>>>>>> Andreas, Joe,
>>> >>>>>>>>>
>>> >>>>>>>>> Reset Button, Reset_Clock added.
>>> >>>>>>>>>
>>> >>>>>>>>> See attached zip for details, or visit link;
>>> >>>>>>>>>
>>> >>>>>>>>>
>>> >>>>>>>>>
>>> https://create3000.github.io/x_ite/playground/?url=https://raw.githubusercontent.com/coderextreme/ci2had/refs/heads/main/resources/CleanedYouClocks.x3d
>>> >>>>>>>>>
>>> >>>>>>>>> For some reason, this link doesn't show the live scene?
>>> >>>>>>>>>
>>> >>>>>>>>>
>>> >>>>>>>>>
>>> https://andreasplesch.github.io/Library/Viewer/index.html?url=https://raw.githubusercontent.com/coderextreme/ci2had/refs/heads/main/resources/CleanedYouClocks.x3d
>>> >>>>>>>>>
>>> >>>>>>>>> Puzzled, haven't researched it yet.  Looks good in Sunrize and
>>> >>>>>>>>> X_ITE, will try FreeWRL next.
>>> >>>>>>>>>
>>> >>>>>>>>> John
>>> >>>>>>>>>
>>> >>>>>>>>>>
>>> >>>>>>>>
>>> >>>>>>>> --
>>> >>>>>>>> Andreas Plesch
>>> >>>>>>>> Waltham, MA 02453
>>> >>>>>>>>
>>> >>>>>>>
>>> >>>>>>
>>> >>>>>> --
>>> >>>>>> Andreas Plesch
>>> >>>>>> Waltham, MA 02453
>>> >>>>>>
>>> >>>>>
>>> >>>>>
>>> >>>>> --
>>> >>>>> Andreas Plesch
>>> >>>>> Waltham, MA 02453
>>> >>>>>
>>> >>>>
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>>
>>
>>
>> --
>> Andreas Plesch
>> Waltham, MA 02453
>>
>>
>>
>
>
> --
> Andreas Plesch
> Waltham, MA 02453
>

-- 
Andreas Plesch
Waltham, MA 02453
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