[x3d-public] computed orientation_changed output

[Andreas Plesch]

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