[Bf-committers] Collada importer/exporter kickout

[Juha Mäki-Kanto]

Hi,

Did some digging into this -> armature animation vs
collada<http://www.pasteall.org/28205/text>

>From testing and looking at the code Blender imports and uses animation
curves directly which isn't good. It'll only match the original in special
circumstances like if the rotation difference between bone's restpose vs
parent's restpose is identity and you're only animating rotations. For
Second Life there is actually a trick to set all restbones to be positive
Y-axis (identity matrix) which apparently then loads correctly there.

It seems that 2.59 did export/import for armatures correctly
(#29082<http://projects.blender.org/tracker/?group_id=9&atid=498&func=detail&aid=29082>);
tested it and the eulers in the file were interpreted to be quaternions
(and the animation works) so the previous system was somewhat aware of this
caveat.

The gist to me is that collada's transformations may not match a program's
internal representation and reinterpreting usually goes via collada data to
full matrix, possibly fix the matrix and then decomposite to curves. It's a
lossy conversion, key's should match but interpolation won't -> you need to
bake/key every frame when importing the curves.



2012/1/11 Sebastian <sebastian at opencollada.org>

> Is there a list containing all COLLADA related bugs somewhere? There are
> only a few, some of them very unspecific, on the 2.6 bug tracker.
>
>
>
> On 11.01.2012 11:06, Ton Roosendaal wrote:
> > Hi,
> >
> > You can count on plenty of people jumping on a patch if you publish it.
> Don't understimate the power of having many eyes looking. If it requires
> more expertise or IO experience, Campbell is around to check on it too.
> >
> > -Ton-
> >
> > ------------------------------------------------------------------------
> > Ton Roosendaal  Blender Foundation   ton at blender.org    www.blender.org
> > Blender Institute   Entrepotdok 57A  1018AD Amsterdam   The Netherlands
> >
> > On 10 Jan, 2012, at 23:39, Juan Linietsky wrote:
> >
> >> Heh I wanted to emphasize that it works, but I seriously do need to work
> >> with someone familiar with writing blender and/or blender import
> plugins in
> >> C++ to do it, who can take my code and adapt it to Blender. It should
> be a
> >> short task for someone with that experience.
> >>
> >> Cheers
> >>
> >> Juan
> >>
> >>
> >> On Tue, Jan 10, 2012 at 6:53 PM, Daniel Salazar - 3Developer.com<
> >> zanqdo at gmail.com>  wrote:
> >>
> >>> That sounds *very* exciting and *very* appropriate for our needs :) OC
> ads
> >>> too much weight to Blender's big ass
> >>>
> >>> Daniel Salazar
> >>> 3Developer.com
> >>>
> >>>
> >>> On Tue, Jan 10, 2012 at 3:48 PM, Juan Linietsky<reduzio at gmail.com>
>  wrote:
> >>>
> >>>> I didn't realize a collada exporter was so important. If so..
> >>>>
> >>>> I have a *very* *tested* and *very* *small* collada importer in my
> >>>> middleware stuff (~3k lines of C++ code). It supports pretty much
> >>>> everything (models, skeletons, materials, cameras, lights, morphs,
> >>> any-axis
> >>>> orientation, animations with matrices or curves, etc).
> >>>>
> >>>> Given it's very small size and non-dependency on OC, it's very easy to
> >>>> understand and *very easy to mantain*. It pretty much just ignores
> >>>> conformance of input files and just attempts to grab wathever data it
> >>> needs
> >>>> so *compatibility is extremely high*.
> >>>>
> >>>> It's not a standalone library, but it's separated enough that *if
> someone
> >>>> knowledgable of blender internals *wants to give a try to adapting it
> to
> >>>> blender (of course with me 100% available for answering questions with
> >>>> this), i think in a matter of a few hours we can solve the Blender
> >>> problem
> >>>> of collada import support. However as I said in previous mails, I
> really
> >>>> lack the time to get familiar with Blender internals and do this
> myself.
> >>>>
> >>>> Cheers
> >>>>
> >>>> Juan Linietsky
> >>>>
> >>>>
> >>>> On Tue, Jan 10, 2012 at 11:30 AM, Erwin Coumans<
> erwin.coumans at gmail.com
> >>>>> wrote:
> >>>>
> >>>>> Until Blender has good fbx import or an alternative collada import
> >>>>> (python?) it would be good to postpone dropping OpenCollada.
> >>>>>
> >>>>>>  From the feedback, some people are using the import feature, and
> there
> >>>> is
> >>>>> no replacement.
> >>>>>
> >>>>> Let's hope someone stands up and fixes the issues in trunk, rather
> then
> >>>>> branch.
> >>>>> On Jan 10, 2012 2:15 AM, "Ton Roosendaal"<ton at blender.org>  wrote:
> >>>>>
> >>>>>> Hi,
> >>>>>>
> >>>>>> The Collada conformance suite is not working, and working on it
> won't
> >>>>> help
> >>>>>> anything.
> >>>>>> I wrote about this here;
> >>>>>> http://code.blender.org/index.php/2011/10/collada-momentum/
> >>>>>>
> >>>>>> Collada just has no reference stakeholder(s) (like how fbx was
> native
> >>>> for
> >>>>>> motionbuilder).
> >>>>>> Blender would be the worst stakeholder for it even, since we have
> the
> >>>>>> awesome .blend :)
> >>>>>>
> >>>>>> Much better stakeholders would be Linden Labs (2nd life), or
> >>> CryTek...
> >>>> or
> >>>>>> Daz? Three names of companies who make plenty of dollars with
> >>> software
> >>>>>> licensing. Why don't they put an employee as developer in our team,
> >>> to
> >>>>>> ensure Collada exports smoothly for their products?
> >>>>>>
> >>>>>> I even wouldn't mind a (python) addon "Export to DazCollada,
> >>>> CryCollada,
> >>>>>> 2ndLifeCollada, etc. It's how collada has been designed to work
> >>>> anyway...
> >>>>>>
> >>>>>> -Ton-
> >>>>>>
> >>>>>>
> >>>>
> ------------------------------------------------------------------------
> >>>>>> Ton Roosendaal  Blender Foundation   ton at blender.org
> >>>> www.blender.org
> >>>>>> Blender Institute   Entrepotdok 57A  1018AD Amsterdam   The
> >>> Netherlands
> >>>>>>
> >>>>>> On 10 Jan, 2012, at 0:25, Sebastian wrote:
> >>>>>>
> >>>>>>> COLLADA has a great conformance test suite at
> >>>>>>> http://www.khronos.org/conformance/implementers/collada/
> >>>>>>>
> >>>>>>> It's being made available for free and I've already seen Blender
> >>>>> results
> >>>>>>> uploaded some time ago.
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>> On 09.01.2012 23:52, spatial wrote:
> >>>>>>>>> For the COLLADA community Blender is definitely one of the most
> >>>>>>>>> important stakeholders to stop supporting COLLADA would make
> >>> things
> >>>>> in
> >>>>>>>>> DCC exchange even worse.
> >>>>>>>> I agree. Not to mention all those who co use it alongside LW , all
> >>>> of
> >>>>>>>> DAZ products....etc.
> >>>>>>>>
> >>>>>>>> I actually tried to avoid a discussion here since a long time,
> >>>>>>>> but topic is too important.
> >>>>>>>>
> >>>>>>>> First, kicking out collada from blender doesn't help anyone. None
> >>> of
> >>>>> the
> >>>>>>>> "common" interexchange formats is that reliable / support all
> >>>>> features.
> >>>>>>>> To have at least a second format as a backup strategy,  if a
> >>> certain
> >>>>>>>> features arent't supported / have some unreliable results, is a
> >>>> "must
> >>>>>>>> have" in every cross application enviroment.
> >>>>>>>>
> >>>>>>>> And btw, blenders FBX import is, from my experience, still not as
> >>>>>>>> reliable as it should be, to actually replace collada. (sorry,
> >>> this
> >>>> is
> >>>>>>>> no actual bashing... its already great what has been archived...
> >>>>>>>> especially if you consider that it is allways pain in the ass, to
> >>>>>>>> support such a complex exchange format)
> >>>>>>>>
> >>>>>>>>> We are currently discussing further financing of OpenCOLLADA and
> >>>> will
> >>>>>>>>> spend more time the next months on bugfixing and conformance
> >>> tests.
> >>>>>>>>>
> >>>>>>>> Sorry to say this, but this is one of the mayor reasons I have to
> >>>> post
> >>>>>> this:
> >>>>>>>>
> >>>>>>>> Conformance tests do only help a little to 0
> >>>>>>>> The big _advantage_ fbx has, is a working reference application
> >>>> called
> >>>>>> maya.
> >>>>>>>>
> >>>>>>>> No conformance test can actually be that foolproof to support all
> >>>>>>>> features and variations. So by this simple unoffical agreement,"if
> >>>> it
> >>>>>>>> doesn't work in maya - it is broken", users and developers have an
> >>>>> ideal
> >>>>>>>> platform to discuss errors / find workarounds.  This greatly
> >>> avoids
> >>>>> the
> >>>>>>>> "picking in the dark" situation all developers currently face with
> >>>>>>>> collada. Even if a dev doesn't have access to it, in a lot of
> >>> cases,
> >>>>> he
> >>>>>>>> can track down problems reported by users who do provide a simple
> >>>>>>>> screenshot.
> >>>>>>>>
> >>>>>>>> Could this collada reference application be Blender ?
> >>>>>>>> For me this is a very attractive idea, but also, I'm very aware of
> >>>> the
> >>>>>> fact,
> >>>>>>>> that I'm opening a can of worms I'm actually in no way in the
> >>> right
> >>>>>>>> position to touch.
> >>>>>>>>
> >>>>>>>> Anyway just my 2 cents on this.
> >>>>>>>> chris
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> _______________________________________________
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> >>>>>>>> Bf-committers at blender.org
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