[Bf-committers] Alembic streaming

[Lukas Tönne]

Hi,

I'd like to point out that using existing types (objects/empties,
shapekey, etc) may not necessarily be a good idea. The design of
Alembic may simply not map very well to existing Blender
scene/object/etc. structures. In my experience it is tempting to try
and use an existing system for a new purpose, simply because it gives
you a familiar environment and a somewhat clear path to follow (a
prime example is the hair system, which was implemented as a variation
of the particle system, but imho actually requires it's own place to
work properly). Forcing a newly designed feature into the shape of an
old concept will just lead to trouble sooner or later ...

Shape keys may work when using Alembic for mesh data, but then what
about fluids, smoke, point clouds, particles,
stuff-we-don't-even-think-about-now?

So, long story short, i suggest to consider adding a new ID type or so
for archives and maybe a distinct component struct to put into Objects
for Alembic support. I'd need to read more about the design to be able
to say if that makes any sense.

Regards,
Lukas

On Mon, Sep 10, 2012 at 4:20 PM, patrick boelens <p_boelens at msn.com> wrote:
>
> Hey guys,
>
> I may be (and probably am) way off about this, but taking only geometry into account, couldn't we use shapekeys for that? I could imagine each frame simply becoming a shapekey, whose panel we could then provide with a "sequence" toggle, making it play all of them in succession. An additional "timescale" slider could then provide additional playback control. This way, users would have full control over the geometry and it seems it would integrate nicely with what's already there.
> I haven't really looked into Alembic at all yet though, so if I am completely missing the point here please pretend I never sent this mail. ;)
>
> Regards,
> Patrick
>
>> Date: Mon, 10 Sep 2012 14:34:38 +0200
>> From: j.bakker at atmind.nl
>> To: bf-committers at blender.org
>> Subject: Re: [Bf-committers] Alembic streaming
>>
>> Hi,
>>
>> The case I am working on is data interchange between departments, where
>> Blender is one of the many tool-sets in use.
>> The use of alembic within blender is:
>>   * export baked animation data to an alembic archive.
>>   * use of alembic archive (baked mesh data) in a blender for vfx or
>> rendering.
>>
>> As you mentioned there are many other areas where Blender could benefit
>> from alembic as cache system, like sims and pointclouds. IMO these are
>> more blender internally managed. But sure, the system should be capable
>> to handle these as well.
>>
>> Jeroen
>>
>>
>> On 09/10/2012 01:34 PM, Ton Roosendaal wrote:
>> > Hi,
>> >
>> > You probably skip a step here; what do you (we) want to have alembic for in the first place?
>> >
>> > To me it seems we would need it for:
>> >
>> > - realtime playback of cached (baked) characters
>> > - smoke, fluid, cloth sims
>> > - general point cloud caches
>> >
>> > All these have a relationship with something in Blender, and can thus live or work within that context as well.
>> >
>> > If you consider to only use Alembic as import format it's barely interesting...
>> >
>> > -Ton-
>> >
>> > ------------------------------------------------------------------------
>> > Ton Roosendaal  Blender Foundation   ton at blender.org    www.blender.org
>> > Blender Institute   Entrepotdok 57A  1018AD Amsterdam   The Netherlands
>> >
>> > On 10 Sep, 2012, at 12:20, Jeroen Bakker wrote:
>> >
>> >> Hi all!
>> >>
>> >> I am looking into realizing Alembic support in Blender. The biggest
>> >> issue on this topic is the Alembic streaming.
>> >> Alembic is not a standard importer/exporter, but can be used as a
>> >> read-only cache file.
>> >>
>> >> My ideas are to use a placeholder (like an empty) and parent all objects
>> >> that are inside the alembic archive. On frame change the data of the
>> >> objects will be refreshed. I think that in the current architecture this
>> >> is the most doable thing, but it has some drawbacks.
>> >>
>> >> The objects are not read-only, they can be edited, but on a frame change
>> >> they will be refreshed. We can make the child objects not selectable in
>> >> the 3d editor, but when doing simulations you need to be able to select one.
>> >>
>> >> Are there other ideas to handle this issue?
>> >>
>> >> Greetings,
>> >> Jeroen
>> >> _______________________________________________
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>> >
>>
>>
>> --
>>
>> Met vriendelijke groet,
>>
>> Jeroen Bakker
>>
>> *At Mind BV
>> *
>>
>> Telefoon: 06 50 611 262
>> E-mail: j.bakker at atmind.nl <mailto:j.bakker at atmind.nl>
>>
>>
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