Subject:
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Re: Is there an origin point specified in LDRAW parts?
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Newsgroups:
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lugnet.cad
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Date:
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Wed, 25 Mar 2009 17:56:47 GMT
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Viewed:
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10818 times
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In lugnet.cad, Geoffrey Hyde wrote:
> If there is an origin point specified in LDRAW part files, I would like to
> know what is needed in order to calculate it's position and alignment to the
> x, y, z coordinate system LDRAW uses.
>
> Can anyone point me to where I can find information that would be useful in
> retrieving the origin point of a LDRAW part, and how for simple parts like
> bricks this could be used to determine the extent of the x, y, z space that
> the part would take up for rectangular parts like bricks?
>
> Are there any utilities available that would show origin points in parts,
> and how they are calculated, and for parts with multiple studs EG 2x4 brick
> where the stud connections would normally be situated?
>
> I was assuming that for every part, like bricks, that the origin point would
> be at some naturally-occurring connection point like a stud or hole. But it
> would seem that this is not always the case, and one document said that the
> parts are always centered on a centre point which the rest of the part would
> be drawn from.
>
> It appears that for the most part, LDRAW model files rely on the user being
> able to properly position the parts on standard values and that there's no
> way of specifying alignment for studs, to describe bricks that would be
> stacked on top of each other physically, for example.
>
> I don't know if we even need such information in parts, or if there's a way
> around it that would eliminate the need for an origin point.
>
> I'm familiar with the way in which rotation matrixes work, and I can
> understand that programs use this to position and rotate parts in models,
> but this is not what I'm after. What I'm after is how could the user
> calculate a part's origin point themselves, should they need to do so, and
> if they're reading in raw part data from a part file and not from a model?
>
>
> Cheers ...
>
> Geoffrey Hyde
Origin of all parts is x=0,y=0,z=0.
Where this origin is placed at the part is different.
Y-Direction:
If the part have studs, then the y=0 is the surface below the studs.
If the part has no studs, then it should be at the top of the part, or in the
middle of the part (wheels etc.) or a assumed best place for rotation in model
files (many technic parts).
All the above applies similar to the x and z directions.
I think there is at present no documention that describes all, because often it
depends on the author and the reviewers of a file.
I hope this answer helps.
cu
mikeheide
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Message is in Reply To:
 | | Is there an origin point specified in LDRAW parts?
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| If there is an origin point specified in LDRAW part files, I would like to know what is needed in order to calculate it's position and alignment to the x, y, z coordinate system LDRAW uses. Can anyone point me to where I can find information that (...) (16 years ago, 25-Mar-09, to lugnet.cad)
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