[Bf-committers] Alembic triangulation

Tue Aug 23 01:23:31 CEST 2016

François,

Shaders are not as important as meterials per face assignments.
Unreal imports materias names and assingnments form Blender Alembics, but
Maya and 3dMax don't. I think it is related to Blender and Unreal beeing
Alembic 1.6.

An update of my findings so far:

https://forums.unrealengine.com/showthread.php?120948-Blender-2-78-Alembic-Unreal-4-13

*Adriano*

2016-08-22 11:45 GMT-03:00 François T. <francoistarlier at gmail.com>:

> 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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> > >
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> > >
> > > Links:
> > > ------
> > > [1] https://developer.blender.org/maniphest/task/edit/form/1/
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>
>
>
> --
> ____________________
> François Tarlier
> www.francois-tarlier.com
> www.linkedin.com/in/francoistarlier
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