[Sugar-devel] Physics activity (Was: Release v3 tonight?)

[Asaf Paris Mandoki]

On Tue, Jul 14, 2009 at 6:27 PM, Gary C Martin <gary at garycmartin.com> wrote:

> On 13 Jul 2009, at 05:46, Asaf Paris Mandoki wrote:
>
>  On 13 Jul 2009, at 03:11, Gary C Martin wrote:
>>
>>  Think we need to make a call on the stability of the new Physics Journal
>>> state format first, or at least make sure everyone knows the storage format
>>> may (or may not) be stable long term (hate to see a bunch of folks
>>> generating/posting examples for lesson plans only to have them all fail to
>>> resume in a few versions from now).
>>>
>>
>> Are we talking about doing something like this?
>>
>> http://wiki.laptop.org/go/Physics_File_Format
>> (See also the discussion)
>>
>> I think the format described there is much too elaborate for our needs
>> although the right thing to do is implement it at the elements level and
>> that may require to do more than what we really need for this activity.
>>
>>  JSON sounds like a good option for the format. I'll look into the api we
>> have available.
>>
>
> Cool, the simpler the better, my main concern would be that we should at
> least have control over the stored format should upstream change (unless
> upstream are willing to offer some guarantee of backwards compatibility in
> box2d if things do need to change).


By looking at the elements api I see that there isn't that much more to to
if I do it at the elements layer so I'll start doing it there. I'll reopen
http://dev.sugarlabs.org/ticket/1034 and post my ideas for the
implementation there so we can comment on them.



>  We should also start considering adding some sort of Save/Load state so
>> it's easier to test tweaks to a contraption.
>>
>
> You mean undo/redo? Save/Load is not a Sugar thing. Hmmm. Undo/redo would
> need to snap shot the state of the entire simulation on every user change...
> Could be a tough one. Of course with Journal state working, the Keep button
> is all about keeping a version of the current state (allowing you to 'stop'
> and resume an earlier 'version') :-)
>

The problem I see with the Keep button is that you have to close the
activity and open it again to restore the state. I'm not talking about
saving to a file it's more like picking a state and then returning to it.
Something like an undo/redo but the snap shots are selected by the user.

Saludos,
Asaf
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