[Bf-committers] Collada importer/exporter kickout

Juha Mäki-Kanto kiskosika at gmail.com
Sun Jan 15 12:21:38 CET 2012 

That being said, would be helpful if someone could give a concrete example
of how the exporter-side fails when skinning (not "bones look different
after collada" * ) or the error in my logic. From looking at the files
produced the animation matrices should be correctly parent space.

* Bones may look different after import/export if they are interpreted as
lines between joints (where a leaf-bone doesn't have a well defined
orientation) or bones just are on different axis.

2012/1/14 Juha Mäki-Kanto <kiskosika at gmail.com>

> 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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