[ANN] ODECo 0.1 is available

Takashi Yamamiya propella at yuri.sakura.ne.jp
Wed Jul 28 04:24:09 UTC 2004


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?

> 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 ;)

> 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.

regards,

Takashi






More information about the Squeak-dev mailing list