[Bf-committers] Collada Development (moving forward)

[Domino Marama]

On 01/31/2012 12:05 AM, Campbell Barton wrote:
> To avoid overwhelming new collada devs with all bugs at once,
> I suggest we try have a single application working for export
> (mesh/rig/animation).
>
> Gaia and I agreed export to SecondLife is a reasonable target to
> support initially since its open-source and 2.4x python exporter was
> compatible.

Second Life doesn't use animations from Collada, so it's only suitable
for testing mesh and rig.It uses bvh (and a custom .anim format) for
animations - so it's a good test for whether Collada rigging is
consistent with bvh export of animations, but not for animations directly.

> Once supported other applications can be made compatible, but always
> keeping SecondLife working.
> This way we always have at least _some_ happy collada users :).
>
> I've mailed 2 developers already to see if they would be interested to
> help with collada support, if there are others - don't be shy!
> Please reply here or mail me direct.
>
>
> On a related note, all our collada reports have been set as `TODO`,
> and are now linked from a wiki page.
> http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Import_Export#OpenCollada
>
>
> Related Issues:
> * A python script may be a better way to go for simple collada
> support, one has been written but I didn't hear of anyone testing it
> or any response as to how well it works.
> ** see thread http://markmail.org/message/5ovtzrs3a2red5ga
I tested and looked into Juan's script. There was an issue where the
matrix is in the wrong place in the file (instead the node rather than
outside - Collada works a bit like turtle graphics with a 3D cursor you
position before adding things). It also only exports triangles, and it
converts quads to triangles in a way that isn't compatible with ngons.
Collada spec says triangulation should be an option on exporters.

Because Second Life doesn't need all the features of Juan's script I
started on an elementtree based Collada export for Second Life rather
than fixing Juan's script at that point in my investigation. It's
currently working 100% for static meshes. But it's slow compared with
Juan's script so I was considering porting my mesh logic into Juan's
script as my next step.

>
>
> Having an export-only python script supporting at least 1 of
> application is quite a feasible as a technical target,
> but also need to see there are devs who are prepared to take on this
> task and be responsible for collada support in blender.
>
Yes there are, and I'm glad to see in the wiki that a review in a year
is mentioned. I started my python alternative and stopped working on
fixing bugs under the threat of Collada being removed. Knowing that we
have a year to get up to speed and improve things encourages me to go
back into the Blender code.

Best Wishes,
Domino