[Sugar-devel] [Physics] New features

[Gary C Martin]

Hi Asaf,

On 1 Sep 2009, at 02:03, Asaf Paris Mandoki wrote:

>> I hope all that olpcgames/pygame wrapper stuff doesn't bite us too  
>> hard ;-)
> From Mike C. Fletcher's email it seems we may be better of without it.
> I'm not quite sure what real advantage does it give us.

I know what you mean –mental reminder I need to reply to his prompt  
email!. There's a heap of scary things going on in olpcgames I don't  
fully understand, and without knowing pygames well enough, I'm not too  
sure of all the fine points of how the wrapper is actually helping us,  
I'm sure it is helping in many... Could take us a while to untangle,  
but might well be worth it (at some point).

OT: Mikes original intention was (I think) to provide a library so  
that you could include it to quickly wrap any old pygame developed  
code into (and under) basic Sugar activity code. It might be better  
just to create a clean/simple (as possible) pygame template Activity,  
that anyone can then clone and drop their pygame code into (like Tomeu  
template efforts for Gnash and Qt). The current case of including of  
multiple layers and wrappers gets pretty confusing trying to track  
down who is actually doing what.

>> It's likely going to be the end of the week before I can spend much  
>> time on
>> Physics.
> Ok, don't worry.
>
>> I can see the need for a "World" tab,
>> and "Material" tab, so that we don't overload on too many features  
>> all at
>> once (i.e a young kid could ignore World and Material tabs, and  
>> just get on
>> with building things as they do now).
> We could also think of a "Tools" tab were we can put all the data
> acquisition tools such as the trail tool and maybe the save/clear
> background options, also we could have the background "paper" move in
> some direction so some sort of plots can be made. (This is just a soup
> of ideas)

We could likely get away with most of these in the "World" tab  
(treating the page canvas that gets drawn onto as part of the world).

> I was also thinking on another new feature. What about joint's
>>> displaying the tension they're in by changing their color?
>>
>> Ooh, yes I like that one, colour would be good, black --> red? Have  
>> you had
>> a look at the old Bridge Activity? It did this for the "rivet"  
>> colour.
> I may have seen It. I also saw it in another Bridge Building Game.
>
> http://www.crypticsea.com/images/bbg1.jpg

Have a quick look at:

	http://wiki.laptop.org/go/Bridge

It was another one of my "someone should really rescue this and  
actually finish it" list ;-) Maybe now we've sharpened our teeth on  
Physics...

>>> We could even break the joints if tension is too high.
>>
>> We could. But perhaps save this for when we have more material  
>> controls else
>> where, quick thought is that once we have a "Materials" tab, there  
>> would be
>> radio buttons for solid links (the default), and breakable links...  
>> (and
>> could we manage a 3rd elastic/stretchy links in the code? That's  
>> another
>> nice way to store potential energy in a contraption).
> I agree on this.
>
>> P.P.S. Did you like the attempt at illustrating longitudinal wave
>> prorogation? It's a but more tricky to set-up than the transverse  
>> wave
>> example, as you need to get the spacing right to see a nice  
>> longitudinal
>> wave propagate before the energy is too dissipated.
>>
>>        http://wiki.sugarlabs.org/go/File:Physics_longitudinal_waves.png
>
> Really nice, would like to see it moving. Maybe I haven't been paying
> enough attention to the mailing list but how can people share their
> creations? Is there a way we can put the data files on the wiki so
> they can be easily downloaded and opened with the activity?


Well if you are running Sugar 0.84 (or better), if I can catch your  
buddy name and "friend" it on jabber.sugarlabs.org I can send you any  
of these right from my Journal with just a couple of clicks! All  
thanks to Tomeu's wonderful "send to --> friend" feature. I now  
routinely round trip Journal objects from UK --> jabber.sugarlabs.org  
--> back to UK again, between 3 machines here. You can send .xo  
bundles like this to...

We might also be able to upload to a web server (if it knows about the  
physics MIME type, might have to ask Bernie about that for the  
SugarLabs wiki), but be warned, that upload/download path is fairly un- 
tested and needs a good thrash out before I'd recommend. Hopefully  
some improvements might land in 0.86 (Browse) but it's still a misty  
road.

Regards,
--Gary