[x3d-public] value_changed event if value does not change

[Andreas Plesch]

Thanks for sharing your thoughts.

> Date: Fri, 1 Feb 2019 11:10:43 -0800
> From: Leonard Daly <Leonard.Daly at realism.com>
>
> Andreas,
>
> > Any takers for below ?
> >
> > To sharpen the question a bit: Would any (known) scene break if
> > interpolators would not generate a value_changed event if the key
> > values stayed the same ? As in the central intervals of keyValue='0 1
> > 1 1 1 0' ?
>
> The only situation I can think of is someone using an interpolator as a
> timed locking switch. For example, a motion sensor that leaves a light
> on in a room for N seconds after the last motion detected. If the value
> of "1" is light on, "0" for off, and the time intervals are the
> beginning and end are very short this would work. However, this is not a
> good solution. It would be better to capture the end of the interval and
> act on that.

I think in this scenario, skipping the events after the light is
initially switched on, would just leave the light switch on. Unless
something else wants to switch the light off. Then the continuous
interpolator output would force the light to stay on which is what may
be intended, perhaps expecting a short flicker. Hm.

This kind of overriding behaviour does not feel like a good solution
but it should be expected to work, I suppose.

> I cannot think of a well-designed solution that would depend on an event
> when there is no change in value.

Thanks again, Andreas

>
>
> Leonard Daly
>
>
> >
> > -Andreas
> >
> > On Wed, Jan 30, 2019 at 9:05 AM Andreas Plesch
> > <andreasplesch at gmail.com <mailto:andreasplesch at gmail.com>> wrote:
> >
> >     x3dom may want to introduce an optimization which would skip
> >     generating a value_changed event for interpolators if the output
> >     value actually did not change. I do not know the background but
> >     one could imagine an automatically generated keyValue array with a
> >     lot of constant sequential values, or just a long interval with
> >     constant values.
> >
> >     It is clear that the spec. requires generating a value_changed
> >     event for each set_fraction input event, even if the value does
> >     not actually change. But what would be a real world scenario where
> >     skipping this generation of constant value_changed event would
> >     functionally break an event chain ? Perhaps there is even an
> >     example somewhere ? Normally, keep feeding in a constant value
> >     would not be expected to change an output.
> >
> >
> >     --
> >     Andreas Plesch
> >     Waltham, MA 02453
> >
> >
> >
> > --
> > Andreas Plesch
> > Waltham, MA 02453
> >
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>
>
> --
> *Leonard Daly*
> 3D Systems & Cloud Consultant
> LA ACM SIGGRAPH Past Chair
> President, Daly Realism - /Creating the Future/
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