From: jpc@tauon.ph.unimelb.edu.au (John Costella)
Subject: Re: TECH: Hierarchical Object Addressing
Date: Wed, 3 Feb 93 9:32:07 EST



> Does anyone have any good methods for addressing parts of an object in a
> software-friendly way? 
> for the purposes of animation etc. I would like to use something like
> 
>         MOVE 'dog' 1, 3, 4
>         ROTATE  'dog' ' rear left shin' 0 30 0
> 
> This is fine if all the parts of the dog are uniquely named, but what if
> they're not? Perhaps I've built the dog out of standard parts from an object
> database and the shin part of a dog's leg is called 'shin' how do I access 
> it?
> 
> My solution was to use a path name:
> 
>         object  'dog'
>         part    'rear:left leg:shin'
 
Aim to abstract the procedure more and more as your system develops.
When you're starting off you'll probably use your first example; when
this becomes unwieldy you'll move to the second. But then even this
might become unwieldy so then you might simply say ``dog walk to fire
hydrant'', ``dog cock leg'', etc. Let the dog worry about how he's
going to move his shins. If the dog then metamorphises from a poodle
into a German Shepherd, only the dog object's code changes, not the
rest of the system.

John

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John P. Costella              School of Physics, The University of Melbourne
jpc@tauon.ph.unimelb.edu.au         Tel: +61 3 543-7795, Fax: +61 3 347-4783
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