[x3d-public] keyValue at first next for Sequencers [was: ScalarSequencer proto repo]

[Andreas Plesch]

On Sat, Nov 11, 2017 at 12:09 AM, Andreas Plesch
<andreasplesch at gmail.com> wrote:
> ..
> Relatedly, for event utility sequencers, what should be the first key
> and keyValue produced by the first next input event if there was no
> previous set_fraction event (as a reference for next) ? Presumably the
> first one in the key and keyValue arrays ?

To demonstrate with an example fragment:

<IntegerSequencer DEF='S' key='0 0.1 0.2' keyValue='2 4 6' />
<ROUTE fromNode='touch' fromField='isActive' toNode='S' toFIeld='next' />

Nothing else in the scene provides input to the sequencer, so the
first 'next' input has to be relative to some default start index. The
question is if the value_changed event from the sequencer will be 2 or
4 after the first next event.

x_ite (and x3dom) will provide 2.

InstantPlayer and the Proto implementation here
http://www.web3d.org/x3d/content/examples/Basic/development/IntegerSequencerPrototype.html
will provide 4.

The spec. is inconclusive from what I can tell. Tooltip is silent.

Will check other browsers.

-Andreas

>
> On Sat, Nov 4, 2017 at 9:13 AM, Andreas Plesch <andreasplesch at gmail.com> wrote:
>> I developed a first ScalarSequence proto here:
>>
>> https://glitch.com/edit/#!/ripe-taxi?path=index.html:65:12
>> https://ripe-taxi.glitch.me/
>>
>> and it works with x_ite. I will test it in other browsers as well.
>>
>> Looking through the examples, I see that persisting state is mostly
>> managed by initializeOnly fields.
>>
>> Interestingly, the BooleanSequencerPrototype example
>>
>> http://www.web3d.org/x3d/content/examples/Basic/development/BooleanSequencerPrototypeIndex.html
>>
>> declares local variables outside of the functions:
>>
>> var key, keyValue;
>>
>> But this is rarely done, and I am not sure if this is covered by the spec.
>>
>> I also noticed that fields of accessType inputOutput are often
>> substituted by the corresponding inputOnly/outputOnly fields.
>> In theory, inputOutput type in a script should enable set_ and
>> _changed events, so I am not sure why this splitting is necessary.
>>
>> For example, is it sufficient for an inputOutput key field to write
>>
>> function set_key(val) { key = val; }
>>
>> to achieve both assigning the new value to the field, and also
>> outputting of a key_changed event ?
>>
>> I think in x_ite it is sufficient but I will need to test.
>>
>> -Andreas
>>
>> On Sat, Nov 4, 2017 at 12:39 AM, Andreas Plesch <andreasplesch at gmail.com> wrote:
>>> Working on a ScalarSequencer proto ,I developed the script which
>>> provides the functionality:
>>>
>>> https://ripe-taxi.glitch.me/
>>>
>>> It seems to work ok using x_ite. In order to maintain internal,
>>> persisting state, the script uses an initializeOnly field:
>>>
>>> https://glitch.com/edit/#!/ripe-taxi?path=index.html:161:21
>>>
>>> Perhaps this is the intended use of such a field but I was wondering
>>> if there are other standard ways to have such internal state storage.
>>> For example, it may be convenient to use a javascript object for state
>>> which could not be a field value.
>>>
>>> It is possible to just use a global variable, initialized in the
>>> initialize() function. However, in an environment such as web page
>>> this would intrude other script sharing the global context. One could
>>> use a namespace then, say script1.globalA
>>>
>>> With x_ite it is possible declare a scoped variable in the script but
>>> outside the functions which then persists and is in the scope of all
>>> script functions but out of scope anywhere outside the script. A good
>>> solution but likely this is not guaranteed to work in other browsers
>>> since the spec. does not cover code execution outside the script
>>> functions.
>>>
>>> Perhaps the namespaced global variable would be the most standard way
>>> but it would be great if global variables could be avoided.
>>>
>>> -Andreas
>>>
>>> --
>>> Andreas Plesch
>>> Waltham, MA 02453
>>
>> --
>> Andreas Plesch
>> Waltham, MA 02453
>
>
>
> --
> Andreas Plesch
> Waltham, MA 02453



-- 
Andreas Plesch
Waltham, MA 02453