takashi,

thanks for your reply, I put a few notes below

regards,
nicholas

>From: Takashi Yamamiya <propella at yuri.sakura.ne.jp>
>Reply-To: The general-purpose Squeak developers 
>list<squeak-dev at lists.squeakfoundation.org>
>To: The general-purpose Squeak developers 
>list<squeak-dev at lists.squeakfoundation.org>
>Subject: Re: [ANN] ODECo 0.1 is available
>Date: Wed, 28 Jul 2004 00:24:09 -0400
>
>Nicholas,
>
> > I just loaded up ode and the examples
> >
> > great fun, fantastic
>
>Thank you for feedback!
>
> > do you mind if I ask a few questions you might know off the top of your
> > head?
> >
> > 1 - is one able to specify constraints on the hinge motion? for example 
>to
> > make an 'elbow'
>
>Original ODE library supports a couple of joint types like ball joint,
>universal joint, or so. I'm going to support all of these joints in
>API level, but I don't sure in etoys level, because etoys is just in
>2-D world and I want to keep the interface easy.
>
>But... What's difference between hinge to elbow? What do you want?

oh, just an elbow has a 0 - 180 degree range of motion. So if you an 
constrain joints then you can make al sorts of 'figures' like 
marionettes/puppets - which will be 'realistic' if you 'shake'/'perturb' 
them.

I started reading the ode docs, the api is huge and has a lot of power. Is 
your goal near total coverage (with a subset only in e-toys)? how close are 
you to your goal?

>
> > 2 - does it do springs (ODE site says 'rigid body'
>
>I also want springs. I don't sure ODE handles springs directly, or
>you can write it in Smalltalk ;)

I read in their docs they have a 'slider' joint that you can add constraints 
to, and that the constraint has 'springiness' - but I've not read enough to 
know what that means exactly.

>
> > 3 - I could not figure out how to get a 'sketch' to be a body that would
> > 'swing' off a hinge, if I made a 'bar' 'look like' a sketch it kind of 
>went
> > dead from an ode perspective
>
>You can just drop any morph in force field. 'bar' in object catalog is
>indeed an instance of Morph, not special object. But now, all objects
>except circle are regarded as rectangle for ODE. I'm going to support
>other complex geometry using 'mesh' feature in ODE.
>
>But probably your problem was just a bug. I have never used
>'look like' feature with ODECo. The property of body is in morph,
>not in player, but your assumption was reasonable.
>
> > 4 - what do you think is the limiting factor for number of bodies? ode 
>or
> > the squeak graphics?
>
>Almost 50 - 100 with small morph. But in many case, performance issue is
>in drawing TransformationMorph.

your SAR mentions croquet, this would be fun in a wonderland also.

>
>regards,
>
>Takashi
>
>
>
>

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