[x3d-public] STEP interpolation, was Blender > Exporting rig transforms to HAnim?
Andreas Plesch
andreasplesch at gmail.com
Tue Jul 18 11:19:55 PDT 2023
I also cannot think of a situation where an additional event without
changes is definitely needed, and I would prefer not to change any
behaviours.
The spec. seems to require sending an event every time:
'The set_fraction inputOnly field receives an SFFloat event and causes
the interpolator node function to evaluate, resulting in a
value_changed output event of the specified type with the same
timestamp as the set_fraction event.'
However, the tool-tips warn:
Hint: X3D players might not send unchanging intermediate values, thus
avoiding excessive superfluous events that have no effect.
Should this language become part of the spec. ? "Browsers may choose
not to generate output events for unchanging intermediate values."
-Andreas
On Tue, Jul 18, 2023 at 2:28 AM Joseph D Williams <joedwil at earthlink.net> wrote:
>
> Two ways to code this:
>
>
>
> <BooleanSequencer DEF='Background3Sequencer'
>
> key='0 0.09 0.11 0.22 0.43 0.55 0.63 0.73 0.85 0.86 1'
>
> keyValue='true true true false false false false false false false true'/>
>
>
>
> <BooleanSequencer DEF='Background1Sequencer'
>
> key='0 0.22 1'
>
> keyValue='true false true'/>
>
>
>
> Both would produce the same number of value_changed events.
>
>
>
> There is only an event out with a new timestamp if the
> new value has changed compared to the last value.
>
>
>
> I don’t think I need a new out event at each keytime. Only if the value_changed is actually changed. I might code the first version thinking that I would get an event at each keytime, regardless. I try to think of some situation where I definitely want an event at each keytime, regardless if out has changed or not. If I need that, I shouldn’t need to depend on this or any interpolator node
>
>
>
> Thanks and Best,
>
> Joe
>
>
>
>
>
>
>
> From: Andreas Plesch
> Sent: Monday, July 17, 2023 7:32 PM
> To: Joseph D Williams
> Cc: Michalis Kamburelis; X3D Graphics public mailing list
> Subject: Re: STEP interpolation, was Blender > Exporting rig transforms to HAnim?
>
>
>
> The way STEP works currently is the same as regular LINEAR
>
> interpolation. There is only an event out with a new timestamp if the
>
> new value has changed compared to the last value. So with STEP there
>
> are only a few events per cycle. Would that work for you?
>
>
>
> In the case of two subsequent, identical keyValues, there is no event
>
> when the second interval is entered. So an alternative may be to emit
>
> an event in this case even if the value did not change. It may be
>
> helpful in some cases and should not affect too much existing
>
> behaviours.
>
>
>
> Andreas
>
>
>
> On Mon, Jul 17, 2023 at 9:59 PM Joseph D Williams <joedwil at earthlink.net> wrote:
>
> >
>
> > I like this and interesting how this works relative to another type of step node, the BooleanSequencer. For any initial state, I expect that the keyvalue will be set at the keytime, remain in that readable state until the next keytime, when the next keyvalue will out.
>
> >
>
> > As expected, the keyvalue has the same time stamp as the keytime event in.
>
> >
>
> >
>
> >
>
> > <X3D profile='Immersive' version='3.3' xmlns:xsd='http://www.w3.org/2001/XMLSchema-instance' xsd:noNamespaceSchemaLocation='http://www.web3d.org/specifications/x3d-3.3.xsd'>
>
> >
>
> > <head>
>
> >
>
> > <meta content='background4.x3d' name='title'/>
>
> >
>
> > </head>
>
> >
>
> > <Scene>
>
> >
>
> > <WorldInfo title='background5.x3d'/>
>
> >
>
> > <Viewpoint DEF='EntryView1' description='Hello character' position='0 2 10'/>
>
> >
>
> >
>
> >
>
> > <Background DEF='Background1' skyColor='0 0 0'/>
>
> >
>
> > <Background DEF='Background2'
>
> >
>
> > groundAngle='1.57' groundColor='0.3 0.6 0 0.7 1 0.5'
>
> >
>
> > skyColor='0 0.71 0.88'/>
>
> >
>
> > <Background DEF='Background3'
>
> >
>
> > groundAngle='1.57' groundColor='0.9 0.39 0.6 0.2 1 0.5'
>
> >
>
> > skyColor='0.82 0.82 0.82'/>
>
> >
>
> > <Background DEF='Background4' skyColor='0.6 0.6 0.6'/>
>
> >
>
> >
>
> >
>
> > <!-- Animation controls -->
>
> >
>
> > <TimeSensor DEF='Clock10Seconds' cycleInterval='10' loop='true'/>
>
> >
>
> >
>
> >
>
> > <BooleanSequencer DEF='Background1Sequencer'
>
> >
>
> > key='0 0.11 1'
>
> >
>
> > keyValue='true false true'/>
>
> >
>
> > <BooleanSequencer DEF='Background2Sequencer'
>
> >
>
> > key='0 0.11 0.55 1'
>
> >
>
> > keyValue='false true false false'/>
>
> >
>
> > <BooleanSequencer DEF='Background3Sequencer'
>
> >
>
> > key='0 0.55 0.85 1'
>
> >
>
> > keyValue='false true false false'/>
>
> >
>
> > <BooleanSequencer DEF='Background4Sequencer'
>
> >
>
> > key='0 0.85 1'
>
> >
>
> > keyValue='false true false'/>
>
> >
>
> >
>
> >
>
> > <ROUTE fromField='value_changed' fromNode='Background1Sequencer'
>
> >
>
> > toField='set_bind' toNode='Background1'/>
>
> >
>
> > <ROUTE fromField='value_changed' fromNode='Background2Sequencer'
>
> >
>
> > toField='set_bind' toNode='Background2'/>
>
> >
>
> > <ROUTE fromField='value_changed' fromNode='Background3Sequencer'
>
> >
>
> > toField='set_bind' toNode='Background3'/>
>
> >
>
> > <ROUTE fromField='value_changed' fromNode='Background4Sequencer'
>
> >
>
> > toField='set_bind' toNode='Background4'/>
>
> >
>
> >
>
> >
>
> > <ROUTE fromField='fraction_changed' fromNode='Clock10Seconds'
>
> >
>
> > toField='set_fraction' toNode='Background1Sequencer'/>
>
> >
>
> > <ROUTE fromField='fraction_changed' fromNode='Clock10Seconds'
>
> >
>
> > toField='set_fraction' toNode='Background2Sequencer'/>
>
> >
>
> > <ROUTE fromField='fraction_changed' fromNode='Clock10Seconds'
>
> >
>
> > toField='set_fraction' toNode='Background3Sequencer'/>
>
> >
>
> > <ROUTE fromField='fraction_changed' fromNode='Clock10Seconds'
>
> >
>
> > toField='set_fraction' toNode='Background4Sequencer'/>
>
> >
>
> >
>
> >
>
> > </Scene>
>
> >
>
> > </X3D>
>
> >
>
> >
>
> >
>
> > Thanks and Preserve the Cascade.
>
> >
>
> > Joe
>
> >
>
> >
>
> >
>
> > From: Andreas Plesch
>
> > Sent: Monday, July 17, 2023 8:59 AM
>
> > To: Michalis Kamburelis
>
> > Cc: X3D Graphics public mailing list; Joseph D Williams
>
> > Subject: Re: STEP interpolation, was Blender > Exporting rig transforms to HAnim?
>
> >
>
> >
>
> >
>
> > Hi Michalis,
>
> >
>
> >
>
> >
>
> > On Mon, Jul 17, 2023 at 9:23 AM Michalis Kamburelis
>
> >
>
> > <michalis.kambi at gmail.com> wrote:
>
> >
>
> > >
>
> >
>
> > > > For STEP, I am using the lower value of the interval:
>
> >
>
> > > ...
>
> >
>
> > > > This corresponds to typical x3d interval use, and you may have done the same ?.
>
> >
>
> > >
>
> >
>
> > > Yes, that is indeed what Castle Game Engine / view3dscene is doing too.
>
> >
>
> > >
>
> >
>
> > > If input is between key[n] and key[n+1], then the output of STEP is keyValue[n].
>
> >
>
> >
>
> >
>
> > Super. There are also the edge cases:
>
> >
>
> >
>
> >
>
> > key[exactly at n] => keyValue[n]
>
> >
>
> > key[< nMin] => keyValue[nMin]
>
> >
>
> > key[> nMax] => keyValue[nMax]
>
> >
>
> >
>
> >
>
> > Just to confirm.
>
> >
>
> >
>
> >
>
> > > I started converting your testcase (
>
> >
>
> > > https://github.com/andreasplesch/x3dom/blob/step_interpolator/test/regression-suite/test/cases/interpolators/interpolators.html
>
> >
>
> > > ) into standalone X3D file. I noticed a few things special to X3DOM I
>
> >
>
> > > think (aside from lowercase node / field names, which I understand is
>
> >
>
> > > just necessary for HTML5 integration):
>
> >
>
> > >
>
> >
>
> > > - "alphaMode" and "alphaCutoff" specified at "PhysicalMaterial", while
>
> >
>
> > > in X3D 4 they are on "Appearance"
>
> >
>
> >
>
> >
>
> > Yes, for historical reasons, because they only apply to PhysicalMaterial.
>
> >
>
> > Appearance has alphaClipThreshold for regular Material in x3dom. There
>
> >
>
> > was some reason why it was not not reused for PhysicalMaterial perhaps
>
> >
>
> > due to shader uniforms or subtle usage differences.
>
> >
>
> >
>
> >
>
> > > - "PhysicalMaterial.unlit" boolean, while in X3D 4 we have separate
>
> >
>
> > > node "UnlitMaterial" instead
>
> >
>
> > >
>
> >
>
> > > - baseColorFactor -> it is baseColor in X3D 4
>
> >
>
> > >
>
> >
>
> > > - metallicfactor, roughnessfactor -> just metallic, roughness in X3D 4
>
> >
>
> >
>
> >
>
> > Will be easy to rename.
>
> >
>
> >
>
> >
>
> > > - diffusefactor, specularfactor, glossinessfactor on PhysicalMaterial
>
> >
>
> > > -> in X3D 4 we follow te glTF standard "metallic-roughness" workflow,
>
> >
>
> > > so there's no no specular / glossinness.
>
> >
>
> >
>
> >
>
> > There used to be specular/glossiness for glTF1. We would probably just
>
> >
>
> > keep it as there is also an extension.
>
> >
>
> >
>
> >
>
> > > In the end, it was a bit easier to take glTF from
>
> >
>
> > > https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/InterpolationTest/glTF
>
> >
>
> > > and open it in view3dscene, or convert to X3D from view3dscene. But I
>
> >
>
> > > know this is not objective test, sure it was easier this way for me to
>
> >
>
> > > just open in CGE/view3dscene :)
>
> >
>
> >
>
> >
>
> > Of course.
>
> >
>
> > x3dom has a different DEF naming convention prefixing with 'glTF_' and
>
> >
>
> > using the node.name when available but I do not think it is necessary
>
> >
>
> > to align.
>
> >
>
> > I noticed the $ character in the DEF names but see
>
> >
>
> > https://www.web3d.org/x3d/content/examples/X3dSceneAuthoringHints.html#NamingConventions:
>
> >
>
> > 'Most restrictive and most interoperable guidance regarding choice of
>
> >
>
> > characters in names: can start with letter or underscore character,
>
> >
>
> > but not a number or a colon. Can then include letters, numbers,
>
> >
>
> > hyphen, underscore, or period characters. This interoperability is
>
> >
>
> > important so that files can be converted equivalently between
>
> >
>
> > encodings without validation problems.'
>
> >
>
> >
>
> >
>
> > Shapes do not get named
>
> >
>
> >
>
> >
>
> > > Quickly scanning view3dscene output, the one CGE/view3dscene-specific
>
> >
>
> > > thing there is "ImageTexture.flipVertically" (we plan to add
>
> >
>
> > > alternative to it, using texture transform for max conformance), the
>
> >
>
> > > rest looks standard X3D 4.
>
> >
>
> >
>
> >
>
> > x3dom has boolean flipY which I believe corresponds to an OpenGl flag.
>
> >
>
> > I also noticed the boolean OrientationInterpolator.keyValueQuaternions
>
> >
>
> > . x3dom converts all rotations from axis-angle to Quaternions during
>
> >
>
> > parsing, so this would save a little bit time there but not during the
>
> >
>
> > animation. I would assume Euler angles would be a more common format
>
> >
>
> > to accept from modeling software but that might be one step too far.
>
> >
>
> >
>
> >
>
> > Thank you for the nice list which will make it more manageable to work through.
>
> >
>
> >
>
> >
>
> > I found another animation example here:
>
> >
>
> > https://github.com/mrdoob/three.js/pull/12907
>
> >
>
> > and uploaded it here:
>
> >
>
> > https://github.com/andreasplesch/Library/blob/gh-pages/Examples/gltf2/interpolation/InterpolationComparison.gltf
>
> >
>
> >
>
> >
>
> > Regards, Andreas
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > >
>
> >
>
> > > Regards,
>
> >
>
> > > Michalis
>
> >
>
> > >
>
> >
>
> > >
>
> >
>
> > > pon., 17 lip 2023 o 07:16 Andreas Plesch <andreasplesch at gmail.com> napisał(a):
>
> >
>
> > > >
>
> >
>
> > > > Hi Michalis,
>
> >
>
> > > >
>
> >
>
> > > > I am putting finishing touches on STEP and CUBICSPLINE interpolation modes.
>
> >
>
> > > >
>
> >
>
> > > > For STEP, I am using the lower value of the interval:
>
> >
>
> > > >
>
> >
>
> > > > key='0 1 2'
>
> >
>
> > > > keyValue='10 11 12'
>
> >
>
> > > >
>
> >
>
> > > > value at key= 0.6 : 10
>
> >
>
> > > > value at key= -0.1 : 10
>
> >
>
> > > > value at key= 2 : 12
>
> >
>
> > > > value at key= 2.1 : 12
>
> >
>
> > > >
>
> >
>
> > > > This corresponds to typical x3d interval use, and you may have done the same ?.
>
> >
>
> > > >
>
> >
>
> > > > I also added CUBICSPLINE to all interpolators except for
>
> >
>
> > > > ColorInterpolator (could be added but seems strange). Doing that I
>
> >
>
> > > > found that for CoordinateInterpolator and NormalInterpolator the
>
> >
>
> > > > layout of keyValues with in and out tangents was most natural this
>
> >
>
> > > > way:
>
> >
>
> > > >
>
> >
>
> > > > keyValue='FrameData1, FrameData2..FrameDataN'
>
> >
>
> > > >
>
> >
>
> > > > where FrameData is the data for a key frame and looks like:
>
> >
>
> > > >
>
> >
>
> > > > [inTangent1, inTangent2 .. inTangentM],
>
> >
>
> > > > [value1, value2 .. valueM],
>
> >
>
> > > > [outTangent1, outTangent2 .. outTangentM]
>
> >
>
> > > >
>
> >
>
> > > > where all entries are Vec3f.
>
> >
>
> > > >
>
> >
>
> > > > The total number of scalar values in keyValue is thus N * 3 * M * 3.
>
> >
>
> > > >
>
> >
>
> > > > I could not test CUBICSPLINE for Coordinate or NormalInterpolator yet
>
> >
>
> > > > since I do not have a test example. Does any scene come to mind ?
>
> >
>
> > > >
>
> >
>
> > > > Perhaps I can augment the Dolphin example with some arbitrary tangents
>
> >
>
> > > > for testing.
>
> >
>
> > > >
>
> >
>
> > > > I also converted the glTF Interpolation Test example to X3D:
>
> >
>
> > > > https://github.com/andreasplesch/x3dom/blob/step_interpolator/test/regression-suite/test/cases/interpolators/interpolators.html
>
> >
>
> > > >
>
> >
>
> > > > It may be useful for testing Position and OrientationInterpolator without glTF.
>
> >
>
> > > >
>
> >
>
> > > > Andreas
>
> >
>
> > > >
>
> >
>
> > > > On Tue, Jun 27, 2023 at 10:34 AM Andreas Plesch <andreasplesch at gmail.com> wrote:
>
> >
>
> > > > >
>
> >
>
> > > > > Hi Michalis,
>
> >
>
> > > > >
>
> >
>
> > > > > Ok, let me work on adding a STEP interpolation mode to interpolators.
>
> >
>
> > > > > Do you want to raise a spec. improvement suggestion ?
>
> >
>
> > > > >
>
> >
>
> > > > > As a side note, STEP mode is also related to x3d sequencers. A
>
> >
>
> > > > > ScalarInterpolator in STEP mode would be equivalent to a hypothetical
>
> >
>
> > > > > ScalarSequencer, except for the next and previous fields. Hm, perhaps
>
> >
>
> > > > > it makes sense to add next and previous fields to interpolators which
>
> >
>
> > > > > would step through intervals.
>
> >
>
> > > > >
>
> >
>
> > > > > The CUBICSPLINE algorithm for glTF is fairly well documented as far as
>
> >
>
> > > > > I remember. Feel free of course to look up the implementation in
>
> >
>
> > > > > x3dom.
>
> >
>
> > > > >
>
> >
>
> > > > > It is worth noting that the existing SplineInterpolator nodes only
>
> >
>
> > > > > allow for one (central) tangent per key and key value, whereas the
>
> >
>
> > > > > common cubic spline algorithm allows for two tangents (in, and out)
>
> >
>
> > > > > per key and key value. Those mathematically inclined may be able to
>
> >
>
> > > > > show that the x3d algorithm for spline interpolations is equivalent to
>
> >
>
> > > > > the cubic spline algorithm with identical in and out tangents.
>
> >
>
> > > > >
>
> >
>
> > > > > x3dom just mirrors glTF in that inTangent, value, outTangent occur in
>
> >
>
> > > > > triplets in the MF keyValue field. An alternative interface would
>
> >
>
> > > > > introduce keyInTangent and keyOutTangent fields which then would
>
> >
>
> > > > > require sensible default values. Not sure.
>
> >
>
> > > > >
>
> >
>
> > > > > Some thoughts, Andreas
>
> >
>
> > > > >
>
> >
>
> > > > > PS:
>
> >
>
> > > > > A StringSequencer would be useful as a mechanism to store and select
>
> >
>
> > > > > alternative string values for display in Text nodes. I think the
>
> >
>
> > > > > current strategy is to use an IntegerSequencer to select from Shapes
>
> >
>
> > > > > in a Switch. A MFStringSequencer would be more concise and convenient.
>
> >
>
> > > > > Hm, similarly there could be a StringTrigger event utility.
>
> >
>
> > > > >
>
> >
>
> > > > >
>
> >
>
> > > > > On Tue, Jun 27, 2023 at 8:18 AM Michalis Kamburelis
>
> >
>
> > > > > <michalis.kambi at gmail.com> wrote:
>
> >
>
> > > > > >
>
> >
>
> > > > > > Indeed glTF has additional interpolation options, and I think it would
>
> >
>
> > > > > > make sense to add them to X3D.
>
> >
>
> > > > > >
>
> >
>
> > > > > > Looks like X3DOM and view3dscene/Castle Game Engine go in this
>
> >
>
> > > > > > direction already :)
>
> >
>
> > > > > >
>
> >
>
> > > > > > 1. X3DOM has SFString "interpolation" field, default "LINEAR", see
>
> >
>
> > > > > > https://doc.x3dom.org/author/Interpolation/X3DInterpolatorNode.html .
>
> >
>
> > > > > > Andreas above explained how it supports "CUBICSPLINE" option.
>
> >
>
> > > > > >
>
> >
>
> > > > > > 2. view3dscene / Castle Game Engine allow to use "STEP" interpolation
>
> >
>
> > > > > > explicitly.
>
> >
>
> > > > > >
>
> >
>
> > > > > > For this, we add such field:
>
> >
>
> > > > > >
>
> >
>
> > > > > > SFString [in,out] interpolation "LINEAR" # range: ["LINEAR"|"STEP"]
>
> >
>
> > > > > >
>
> >
>
> > > > > > .. to all X3DInterpolatorNode descendants (so, all interpolator
>
> >
>
> > > > > > nodes). This seems exactly like X3DOM, we just added "STEP", where
>
> >
>
> > > > > > X3DOM added "CUBICSPLINE". In the end we should probably have all
>
> >
>
> > > > > > ["LINEAR"|"STEP"|"CUBICSPLINE"].
>
> >
>
> > > > > >
>
> >
>
> > > > > > 3. Note that even without this field, with default linear
>
> >
>
> > > > > > interpolation, it was possible to have effectively step interpolation,
>
> >
>
> > > > > > as Andreas mentions. You can just duplicate keys in the middle, like
>
> >
>
> > > > > >
>
> >
>
> > > > > > key [0 0.33 0.33 0.66 0.66]
>
> >
>
> > > > > > keyValue [10 10 20 20 30 30]
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> >
>
> > > > > > # interpolation "LINEAR"
>
> >
>
> > > > > >
>
> >
>
> > > > > > This is valid with X3D ("""keys shall be monotonically
>
> >
>
> > > > > > non-decreasing""" according to spec).
>
> >
>
> > > > > >
>
> >
>
> > > > > > It is equivalent to
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> >
>
> > > > > >
>
> >
>
> > > > > > key [0 0.33 0.66]
>
> >
>
> > > > > > keyValue [10 20 30]
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> >
>
> > > > > > interpolation "STEP"
>
> >
>
> > > > > >
>
> >
>
> > > > > > Using explicit "STEP" is slightly better, as you need 50% less
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> >
>
> > > > > > memory to store it, less computation (no need to do lerp or detect
>
> >
>
> > > > > > this special case to optimize), and seems just simpler for authors --
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> >
>
> > > > > > it specifies intention explicitly, which makes sense, also if one
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> >
>
> > > > > > hopes a round-trip e.g. import to Blender and export to Blender.
>
> >
>
> > > > > >
>
> >
>
> > > > > > Having such additional interpolation options seems common, glTF
>
> >
>
> > > > > > and Blender too have them (
>
> >
>
> > > > > > https://docs.blender.org/manual/en/latest/editors/graph_editor/fcurves/properties.html#editors-graph-fcurves-settings-interpolation
>
> >
>
> > > > > > ).
>
> >
>
> > > > > >
>
> >
>
> > > > > > 4. Note that view3dscene / Castle Game Engine do not support
>
> >
>
> > > > > > "CUBICSPLINE" interpolation yet, but we plan to.
>
> >
>
> > > > > >
>
> >
>
> > > > > > For now we support curve interpolation by adding extra
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> >
>
> > > > > > intermediate keys to the linear interpolation -- so, we have
>
> >
>
> > > > > > needlessly more keys / key values. But this is only a temporary
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> >
>
> > > > > > solution, we want to support "CUBICSPLINE" properly, like X3DOM.
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> >
>
> > > > > >
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> >
>
> > > > > > Regards,
>
> >
>
> > > > > > Michalis
>
> >
>
> > > > > >
>
> >
>
> > > > > > niedz., 25 cze 2023 o 05:33 Andreas Plesch <andreasplesch at gmail.com> napisał(a):
>
> >
>
> > > > > > >
>
> >
>
> > > > > > > > Date: Sat, 24 Jun 2023 10:11:03 -0700
>
> >
>
> > > > > > > > From: Joseph D Williams <joedwil at earthlink.net>
>
> >
>
> > > > > > > > To: Michalis Kamburelis <michalis.kambi at gmail.com>
>
> >
>
> > > > > > > > Cc: GPU Group <gpugroup at gmail.com>, X3D Graphics public mailing list
>
> >
>
> > > > > > > > <x3d-public at web3d.org>
>
> >
>
> > > > > > > > Subject: Re: [x3d-public] Blender > Exporting rig transforms to HAnim?
>
> >
>
> > > > > > >
>
> >
>
> > > > > > > > Which shows that yes, you have a list of the key times that just have to be ascending. Default is linear interpolation between keyvalues. Now new to me, I like the STEP option where value not interpolated but stays the same until next keyvalue change. For that effect, gltf makes it easier. I want that STEP option in x3d! And then there is also the cubic spline with specified tangents. Me want that one too.
>
> >
>
> > > > > > >
>
> >
>
> > > > > > > In order to support glTF x3dom added a CUBICSPLINE with tangents
>
> >
>
> > > > > > > option to interpolators, in the same form as glTF, eg. three values
>
> >
>
> > > > > > > (in tangent, value, out tangent) per key. Parallel to glTF x3dom
>
> >
>
> > > > > > > interpolators have a "interpolation" SFString field which can have
>
> >
>
> > > > > > > "LINEAR" and "CUBICSPLINE" values. I suspect due to glTF support other
>
> >
>
> > > > > > > viewers also already do something like that and could expose such a
>
> >
>
> > > > > > > mode to regular X3D.
>
> >
>
> > > > > > >
>
> >
>
> > > > > > > A STEP option is already elegantly solved by X3D with duplicate keys
>
> >
>
> > > > > > > with different values in series. That allows mixing step wise and
>
> >
>
> > > > > > > linear interpolation in one animation. x3dom just translates glTF STEP
>
> >
>
> > > > > > > to that format which is very straightforward. A dedicated STEP option
>
> >
>
> > > > > > > would be 50% more efficient in storage but I am not sure if this is
>
> >
>
> > > > > > > enough of a benefit to justify duplication of existing functionality.
>
> >
>
> > > > > > > It may not or it may as x3dom already does it internally for glTF. It
>
> >
>
> > > > > > > would be possible to add to x3d as well but perhaps not necessary.
>
> >
>
> > > > > > >
>
> >
>
> > > > > > > Andreas
>
> >
>
> > > > > > >
>
> >
>
> > > > > > > _______________________________________________
>
> >
>
> > > > > > > x3d-public mailing list
>
> >
>
> > > > > > > x3d-public at web3d.org
>
> >
>
> > > > > > > http://web3d.org/mailman/listinfo/x3d-public_web3d.org
>
> >
>
> > > > >
>
> >
>
> > > > >
>
> >
>
> > > > >
>
> >
>
> > > > > --
>
> >
>
> > > > > Andreas Plesch
>
> >
>
> > > > > Waltham, MA 02453
>
> >
>
> > > >
>
> >
>
> > > >
>
> >
>
> > > >
>
> >
>
> > > > --
>
> >
>
> > > > Andreas Plesch
>
> >
>
> > > > Waltham, MA 02453
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > --
>
> >
>
> > Andreas Plesch
>
> >
>
> > Waltham, MA 02453
>
> >
>
> >
>
>
>
>
>
>
>
> --
>
> Andreas Plesch
>
> Waltham, MA 02453
>
>
--
Andreas Plesch
Waltham, MA 02453
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