[Bf-funboard] Reasoning behind child - parent coordinates

[Alberto Torres]

That secret parent-child relationship is not even accessible via the Python
API. I had to derive it from the parent and child matrices. There should be
a way to reset that easily to zero. Asking if we want to transform all
actions to reflect that change, and informing if that would break something.

It can be easily made into an add-on. But IMHO it should be the regular
behaviour when parenting with no conflicts (actions used by different
objects with different parent relationships, constraints that use local
coordinates, parent-relative scale).

On Fri, Apr 17, 2015 at 9:59 PM, Gatis Kurzemnieks <
gatis.kurzemnieks at gmail.com> wrote:

> I dont think it is because of dependancy graph (My guess).. I think it is
> just a weird design decision.
> On Fri 17 Apr 2015 at 20:51 Jeffrey <italic.rendezvous at gmail.com> wrote:
>
> > I would hope so. I've found this functionality very confusing myself. We
> > should at least be able to access the offset as a setting.
> >
> > On 04/17/2015 09:59 AM, Knapp wrote:
> > > On Fri, Apr 17, 2015 at 6:00 PM, Gatis Kurzemnieks <
> > > gatis.kurzemnieks at gmail.com> wrote:
> > >
> > >> Hello.
> > >> I am wondering what is the logic behind Blenders weird coordinate
> > >> calculations when doing parenting operations. What I mean is that
> child
> > >> objects local coordinates are not real local in relation to parent,
> but
> > >> there is the hidden "origin" transformation "matrix_parent_inverse"
> > which
> > >> is not represented in UI in any way.
> > >> Simple example : Create two objects at 0,0,0. Move one object
> somewhere
> > and
> > >> then take the first object (still at 0,0,0) and parent it to moved
> > object.
> > >> You would expect that child objects coords would now be offset
> relative
> > >> from parents, but no - they are still 0,0,0. I mean come on - when
> > childs
> > >> local coords are 0,0,0 it should be in the origin of it's parent,
> > right!?
> > >>
> > >> There is a command "Make Parent without Inverse" that parents without
> > the
> > >> hidden offset, but it destroys the real offset - putting child in the
> > >> center of parent and this is bad. There is also a command called Clear
> > >> Origin, that does something similar (but not exactly and not always -
> > and
> > >> it is not clear to me what and why. It takes Alt O, Alt G, Alt O again
> > to
> > >> clear origin and coords completely in some situations).
> > >>
> > >> I can't see any benefit, reason or logic behind this. This makes
> things
> > >> confusing and conflicts with the way other 3d apps work. And I can't
> > find a
> > >> simple solution (besides writing my own python script which I did), to
> > get
> > >> normal parenting behavior.
> > >>
> > >>
> > >> best wishes,
> > >> Gatis
> > >> _______________________________________________
> > >> Bf-funboard mailing list
> > >> Bf-funboard at blender.org
> > >> http://lists.blender.org/mailman/listinfo/bf-funboard
> > >>
> > >
> > > Just a guess, but could this be yet another strangeness of the old
> > > dependency graph that the devs are working hard to repair/rewrite??
> > >
> > >
> >
> > --
> > Jeffrey "Italic_" Hoover
> >
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> > Bf-funboard at blender.org
> > http://lists.blender.org/mailman/listinfo/bf-funboard
> >
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