Special:
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[DAT] (requires LDraw-compatible viewer)
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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 12:01:13 GMT
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Viewed:
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2429 times
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> How about 3d modeling Parent->Child relationships
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; Object=Minifig01.RightArm (#009)
0 Name: @MyAn000.009
0 Author: T E
0 LDraw Animation Frame Object File
0 [Parent Object]
0 Parent Object is Minifig01.Torso
0 [This Object]
1 16 0 0 0 1 0 0 0 1 0 0 0 1 982.dat
0 [Child Objects]
1 14 -5 18 -10 1 0 0 0 0.73 -0.64 0 0.64 0.73 983.dat
0
Every Object has an unique name (like Minifig01.RightArm) and an unique index
number (009 in the example above).
> When the Parent part moves, All children move in relation to it, including
> rotation
So far, I can follow you. This is already done by LDA2005. Now, I need a way to
store the parent/child relations to be able to build libraries of objects and
not having to create them again each time, and (another?) way to store what I
call behaviours, like walk, run, march, jump...
I think that MPD:s (that I first rejected, but now find to be a good idea) may
be able to handle to parent/child relations in a good way, but I need time to do
some experimenting on that first.
> (Unless they are Tracking to another object). This is the common
> practice in 3D Modeling/Animation tools.
Don't know what Tracking is, and the lunch break is over. Have to get back to
work now. I'll study the rest of the replies later tonight.
Thanks,
/Tore
> 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 is in Reply To:
 | | Re: Thoughts on File Format for LDraw Animation
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| In lugnet.cad.dev, Kevin L. Clague wrote: <snip> (...) Too true! (...) 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 (...) (19 years ago, 26-Oct-05, to lugnet.cad.dev)
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