Subject:
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Re: Thoughts on File Format for LDraw Animation
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Newsgroups:
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lugnet.cad.dev
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Date:
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Wed, 26 Oct 2005 07:55:24 GMT
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Viewed:
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2396 times
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In lugnet.cad.dev, Kevin L. Clague wrote:
<snip>
> Groups fail you because you cannot nest groups.
Too true!
> You want a hierachical model for a minifig including named sub-parts that you
> can effect: left-arm, left-hand, left-leg, torso, right-arm, right-hand,
> right-leg, head.... plus the ability to add things like minifig tools, hats, and
> other accessories and relate them to specific sub-parts (e.g. right-hand sword).
>
> You are going to want rotation axis for each sub-component, as well as the
> ability to move each sub-component. Furthermore if you move the entire minifig,
> all sub-components must move along.
>
> So a super-set of LDRAW 1.0.0 file format is needed that lets you define
> compound parts (separate ldraw file?) and have the whole part and all
> sub-components named. With names, you can modify attributes, rotation,
> position, color, part type....
>
> Wow, you've taken on a lot.
>
> I can kinda follow your ideas, but it makes my brain hurt.
>
> Kev
How about 3d modeling Parent->Child relationships
When the Parent part moves, All children move in relation to it, including
rotation (Unless they are Tracking to another object). This is the common
practice in 3D Modeling/Animation tools.
Another I've seen, used in conjunction with Parenting, is Tracking. This allows
an object to be Rotate to face another object on an axis, while being Moved by
it's Parent. with Parenting relationships an empty handle object could be
defined to contain multiple parts, including other handles et cetera. Then when
the mast handle is moved, it moves all of it's children down the tree. This
would also leave it possible to reposition a child object in relation to it's
parent. Finally, if there were an object naming convention (beyond the basic
part file name) such as from end of file field to end of line, or even a simple
string field with no allowed spaces on the end, you would be more able to use
some form of meta command to rotate a uniquely named object in a model (Whether
that object was a group handle (Empty) or an part. The parenting relationship
would thusly create all the motion of the children.
So you'd have
EXISTING LDRAW Line Format <Unique_Part_Name> <Parent_Name> <Track_Part_Name>
<Nonvolatile_Axis> <Volatile_Axis>
Unique_Part_Name would be unique to each piece in a model, even if it was just
2795_001 and 2795_002 (likely software defaults)
Parent_Name would be Null for no parent or the name of another piece's
Unique_Part_Name
Track_Part_Name would be the Unique_Part_Name to track rotation to.
Nonvolatile_Axis would be the Axis the part will rotate on (X/Y/Z)
Volatile_Axis would be the part Axis which is tracking to Track_Part_Name
(X/-X/Y/-Y/Z/-Z)
I hope that makes sense.
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Message has 1 Reply:
 | | Re: Thoughts on File Format for LDraw Animation [DAT]
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| (...) This is the way LDA2001/2005 already works on the inside. Here's a temporary object file, created by LDA2005, before it is inlined into its parent and grandparent files and, after that, deleted: 0 Project=MyAn; Frame #000; (...) (19 years ago, 26-Oct-05, to lugnet.cad.dev)
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Message is in Reply To:
| | Re: Thoughts on File Format for LDraw Animation
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| (...) <snip> (...) One of the weaknesses of the LDraw file format is that part instances do not have names. This makes it impossible to modify attributes about the part instance. The closest thing we have to date is named groups provided by MLCad. (...) (19 years ago, 25-Oct-05, to lugnet.cad.dev)
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