[x3d-public] computed orientation_changed output

Andreas Plesch andreasplesch at gmail.com
Fri Aug 30 14:24:48 PDT 2024


Exactly, there is precedence. So should we consider making this also
available for a regular PositionInterpolator ?

My particular use case was for a GeoPositionInterpolator. So perhaps
we need a GeoNurbsPositionInterpolator and
GeoNurbsOrientationInterpolator. They would work by translating the
controlPoints from geosystem coordinates to geocentric coordinates
first, construct the corresponding NurbsInterpolator, interpolate with
the fraction and translate back the interpolated value to geosystem
coordinates.

Best regards, Andreas

On Fri, Aug 30, 2024 at 4:13 PM Holger Seelig <holger.seelig at yahoo.de> wrote:
>
> It looks like the NurbsOrientationInterpolator can do just that, align the orientation along a path.
>
> https://www.web3d.org/documents/specifications/19775-1/V4.0/Part01/components/nurbs.html#NurbsOrientationInterpolator
>
> Best regards,
> Holger
>
> --
> Holger Seelig
> Leipzig, Germany
>
> holger.seelig at yahoo.de
> https://create3000.github.io/x_ite/
>
> Am 27.08.2024 um 03:57 schrieb Andreas Plesch via x3d-public <x3d-public at web3d.org>:
>
> Thanks for the input. To clarify, I was thinking of aligning the
> orientation of a rigid object (such as a ship) with its changing
> direction of travel.
>
> Regards, -Andreas
>
> On Mon, Aug 26, 2024 at 4:08 PM John Carlson <yottzumm at gmail.com> wrote:
>
>
> Andreas, I read through this, and I suggest a LineSegmentInterpolator that animates a line segment.  One can also interpolate between curves, surfaces and Text strings/fonts through interpolation (morphing or displacement).
>
> In general, perhaps these are called transitions.
>
> Perhaps one could use two interpolators, one for the previous positions and one for the new positions.  I don’t know how two interpolators can adjust the same object though.
>
> On Mon, Aug 26, 2024 at 2:19 PM Andreas Plesch via x3d-public <x3d-public at web3d.org> wrote:
>
>
> An idea for enhancement:
>
> I had a need for a PositionInterpolator to animate an object (say a
> ship). While moving the object around it should align its orientation
> with the direction of travel (bow pointing forward) which is often the
> case. Rather than precomputing key values for an
> OrientationInterpolator to go along with the interpolated positions, I
> decided to derive the orientations from the change in positions
> dynamically. Perhaps not surprisingly, this required a script. Is
> there an existing alternative ? Perhaps via physics ?
>
> The script takes a new position, calculates the direction of travel as
> the difference between the new position, and the last position (which
> it remembers), and uses a default SAI function to compute the rotation
> from the default (0,0,-1) orientation to the new direction. This
> sounds pretty straightforward but becomes more complicated for a
> GeoPositionInterpolator.
>
> Since aligning orientation with direction of travel is a frequent use
> case - including for animated Viewpoints - , the enhancement would be
> for nodes such as position interpolators, chasers and dampers, etc. to
> provide this orientation directly, perhaps as an additional
> orientation_changed event.
>
> An alternative may be use of a TransformSensor which could
> additionally provide this information, say as a direction_changed
> event.
>
> This may be outside the scope of standard X3D since it may be seen as
> a use case for a Script node but is so generally useful that it may
> warrant enhancement of existing nodes.
>
> Thanks for reading and any thoughts or criticism,
>
> Andreas
>
> --
> Andreas Plesch
> Waltham, MA 02453
>
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>
>
>
> --
> Andreas Plesch
> Waltham, MA 02453
>
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-- 
Andreas Plesch
Waltham, MA 02453



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