[x3d-public] computed orientation_changed output

[John Carlson]

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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