[x3d-public] Discussion of TimeSensor Controls

[Leonard Daly]

Mike McCann and I have been having a private discussion that we both 
thought should be put on x3d-public and perhaps x3dom-users.

I had announced the initial availability of a new node in work that I am 
doing for V4. This node is a functional replacement for TImeSensor and 
the various interpolation nodes. It is called Animate. I will go into 
more detail on that node later on. The particular question also arises 
with V3.x nodes.

Mike was wondering what it would take to have an HTML slider that would 
show where in the animation loop and allow control of playback, much 
like a slider on an audio or video playback you might find with YouTube, 
NetFlix, etc.

IOW, in hands-off mode, the slider moves from start to finish as 
fractional time advances. This is easy to implement as you can get the 
fractional time value and apply it to the slider position.

In hands-on mode, a button-click on the slider needs to pause the time 
control. A drag on the slider would change the fractional time of the 
sensor and button release would start playback from that position. Also 
clicking at a location on the slider widget would have the same effect 
as a drag.

TimeSensor has 'startTime', 'pauseTIme', 'resumeTime', and 'stopTIme' 
fields. This all take local-time in seconds from epoch as the time of 
action. There is also 'cycleInterval' for the duration of a single pass, 
and 'loop' to indicate if the animation should repeat.

To implement a controlling slider, it would be nice to have 'pause' and 
'resume' fields that pause and resume the sensor without needing to 
explicitly supply time. For the slider to control where (when?) in the 
playback, it might be possible to manipulate the existing 'startTime' 
and 'stopTIme' fields to achieve the desired results, but some of those 
changes are ignored if the TImeSensor is currently active (paused counts 
as active).

I think adding a new field called (something like) 'set_fraction' would 
make the user's work much easier and obvious. This would set the current 
fractional time and everything would proceed from there.

There are open questions when things need to run for certain and 
specific intervals. For example, an animation needed to run from 11:03 
to 11:05 local time. At 11:04:48 (fractional time = 0.9) someone changes 
the fractional time to 0.1 (essentially 11:03:12).

1) Is this a case of not a spec problem, because the developer needs to 
ensure this kind of integrity
2) This is a security issue that needs to be handled inside the X3D 
application
3) This is a major vulnerability that needs specification definition
4) This is interpreted code that is run on the user's computer and there 
is nothing that can be done.
5) Something else or not listed.




-- 
*Leonard Daly*
3D Systems & Cloud Consultant
X3D Co-Chair on Sabbatical
LA ACM SIGGRAPH Chair
President, Daly Realism - /Creating the Future/
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