[Bf-committers] Alembic triangulation

Mon Aug 22 16:45:04 CEST 2016

Alembic doesn't contain any information about the unit. You have to make it
a convention in your project. If in blender 1 unit = 1 meter for you, then
you need to set the proper unit system in Maya which will be in cm at the
system level. We did a patch on the alembic I/O of Maya (you can find it on
the alembic github) which use the unit of the maya scene rather than
assuming that the alembic is in cm (which what is the default I/O in maya
does). But know that Alembic only stores generic unit.

For materials, there is no such information in Alembic file format. Only
shading groups (or material assignation per face as you might name it). So
you cannot exchange shaders or material parameters with Alembic. You will
need a script in your dcc which binds a material based on it's name and the
shading group stored in the Alembic. (alembic is just a geometry cache)

cheers,

F.

2016-08-20 14:51 GMT+02:00 Adriano Oliveira <adriano.ufrb at gmail.com>:

> Kévin,
>
> I treasure your Alembic iniciative and I wish to help. I am just performing
> some tests before judging what it is or is not a bug. In the prosses I will
> give some constructive feedback here.
>
> Blender-Alembic-Blender seams ok. I am performing some testes in this
> plataforms: Unreal 4.13, 3ds Max 2017 (educational), Maya 2017
> (educational).
>
> Findings on importing Alembic character animation from Blender:
>
> 1. Unreal 4.13 (preview 2): Issues with rotation (y-z) and scale (cm-m).
> Bad normals from Blender (ok from Max). Animation and meshes are ok.
>
> 2. 3ds Max 2017 (Educational): Rotation/sacale ok. Bad normals. No
> materials. Animation and meshes are ok.
>
> 3. Maya... soon...
>
>
> At this moment, I would say that normals are problematic.
>
> I will report bugs as soon as I have solid tests.
>
>
>
> *Adriano A. Oliveira*
> Professor Adjunto do Curso de Cinema e Audiovisual
> Universidade Federal do Recôncavo da Bahia (UFRB)
> Centro de Artes Humanidades e Letras (CAHL)
> Matrícula: 1673892
> (71) 99181-0123 [VIVO] / (71) 99146-8523 [TIM]
>
> 2016-08-19 23:56 GMT-03:00 Kévin Dietrich <kevin.dietrich at mailoo.org>:
>
> > Please use the bug tracker [1] to report bugs/issues, with simple
> > example files to reproduces them.
> >
> > If one software can open an Alembic file from Blender without issues,
> > and another can't, for basic things like normals, then the bug is mostly
> > likely in the other software, not Blender, we don't do anything fancy
> > here. Also, can 3ds Max import materials from other software without
> > issues?
> >
> > Le 2016-08-20 04:38, Adriano Oliveira a écrit :
> >
> > > ....
> > >
> > > bf48750
> > >
> > > 3) Bad normals when importing from Blender-Alembic into Unreal 4.13 and
> > 3ds
> > > Mac 2017.
> > >
> > > 4) 3ds Max doesn't import materials from Blender-Alembic. Unreal 4.13
> > does.
> > >
> > > *Adriano A. Oliveira*
> > > Professor Adjunto do Curso de Cinema e Audiovisual
> > > Universidade Federal do Recôncavo da Bahia (UFRB)
> > > Centro de Artes Humanidades e Letras (CAHL)
> > > Matrícula: 1673892
> > > (71) 99181-0123 [VIVO] / (71) 99146-8523 [TIM]
> > >
> > > 2016-08-19 19:36 GMT-03:00 Adriano Oliveira <adriano.ufrb at gmail.com>:
> > >
> > > Kévin,
> > >
> > > I am very interested in the workflow Blender-Unreal through Alembic.
> The
> > > idea is to use Unreal for real time rendering.
> > > Alembic in Unreal 4.13 is in preview state, so it will improve a lot.
> > >
> > > Some findings:
> > >
> > > 1) Alembic is very usefull to export destruction simulations. I used
> Cell
> > > Fracture to explode a cube and it produces houndreds of n-gons objects.
> > On
> > > importing into Unreal, it gives errors. I think this would justify an
> > > triangulation option, as in OBJ export.
> > >
> > > 2) I have some crashes on importing Alembic animated characters into
> > > Blender or Unreal that was exported without Flatten Hierarchy.
> > >
> > > ;)
> > >
> > > *Adriano A. Oliveira*
> > > Professor Adjunto do Curso de Cinema e Audiovisual
> > > Universidade Federal do Recôncavo da Bahia (UFRB)
> > > Centro de Artes Humanidades e Letras (CAHL)
> > > Matrícula: 1673892
> > > (71) 99181-0123 [VIVO] / (71) 99146-8523 [TIM]
> > >
> > > 2016-08-19 19:10 GMT-03:00 Kévin Dietrich <kevin.dietrich at mailoo.org>:
> > >
> > > Le 2016-08-19 23:53, Adriano Oliveira a écrit :
> > >
> > > Hi,
> > >
> > > Is it possible to have an option to triangulate mesh on Alembic export.
> > I am trying to import a animation from Blender to Unreal 4.13 and the
> late
> > > ask for tri or quad faces.
> > >
> > > Also it would be nice to have Z to Y convertion options, as long as
> > Unreal rotates the Alembic imports form Blender.
> > >
> > > Congratulations for the grate job!
> > >
> > > *Adriano A. Oliveira*
> > > _______________________________________________
> > > Bf-committers mailing list
> > > Bf-committers at blender.org
> > > https://lists.blender.org/mailman/listinfo/bf-committers
> > > Hi,
> > >
> > > Adding an option to triangulate meshes in the exporter wouldn't that
> > > much of a trouble (though it would have to wait for after the 2.78
> > > release), but I have to ask what prevents you from triangulating the
> > > meshes before exporting? If you've got a lot of objects to triangulate,
> > > a simple Python script can be written to automate the process. Shall it
> > > be a destructive operation, or shall it preserve the state of the
> meshes
> > > (meaning meshes in Blender are not triangulated, but the exported ones
> > > are)?
> > >
> > > For the axis conversion, Alembic files written from Blender follow the
> > > Alembic Y-up convention, so I guess this is already what you want? I do
> > > plan on adding support for more (custom) axis conversions though.
> > >
> > > Regards,
> > >
> > > Kévin Dietrich.
> > > _______________________________________________
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> > > https://lists.blender.org/mailman/listinfo/bf-committers
> >
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> >
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> > ------
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François Tarlier
www.francois-tarlier.com
www.linkedin.com/in/francoistarlier