[Bf-committers] Need ideas on COLLADA improvement for GSoC

Daniel Balster dbalster at gmail.com
Wed Mar 21 12:00:24 CET 2012

Hi Arystanbek,

...I just started a new COLLADA feature at home a few weeks ago:
profile_GLES. Since it goes beyond a small set of bug fixes it should go
into a review/approval process.

Problem description:

profile_COMMON does not make me happy. Normally you write your "cool"
shaders manually and feed them with parameters - but in profile_COMMON
everything is hard-wired:
- it's hard to match blender's current material+textures into a
profile_COMMON effect
- if you want to use COLLADA with custom shaders, you're missing a lot of
- just have a look at the <bump> hack
- normally you have a shader (ie "skinning") that can be used for multiple
different models that only differ in a specific material setting (ie
textures). Currently it's not possible to create a material/effect with
exchangable samplers.

My current COLLADA feature:

profile_GLES (or Cg, GLSL,...) is much more versatile since it lets you
spit out a lot of generic parameters, passes and even the actual shader

- via #ifdef I'm exporting <profile_GLES> instead of <profile_COMMON>
- I'm just spitting out a lot of <newparam> for everything I'm aware of.
- by convention, I'm splitting blender's material name into "prefix-" and
"shader", ie "Material.001-skinning"
- if the current blender document contains text scripts called
"skinning.fs" and "skinning.vs", they're exported in the <code> section of
- otherwise an external reference to "skinning" is written.
- additionally, I tried to hijack the current GLSL renderer to use these
shaders to mimic my intended game effects (not working so far)

So, if you like the idea I could write a clear feature design document and
contribute some code as a starting point. Since this is a very specific
workflow it will need some reviews - especially how to interpret all of
this in the import case (ie load shaders as text documents and bind them to
the GLSL renderer? convert to node graph? ...)

Another not yet finished feature/bugfix is support for exporting
binormals/tangents in meshes. Currently I'm doing this as a post process
after importing a COLLADA file in my engine, checking for <bump> and
regenerating normals and tangents by myself. Would be great if blender
could do this as well.

best regards,

On Wed, Mar 21, 2012 at 7:47 AM, Arystanbek Dyussenov
<arystan.d at gmail.com>wrote:

> Hi,
> This year I want to take part in improving the situation with collada
> im/export as a part of GSoC. I plan to fix priority issues, currently faced
> by collada users. I will post my proposal to this mailing list, after I
> prepare it.
> I am not the only student, who would like to work on collada this year and
> there's a possibility of other student or me adding new functionality to
> collada support.
> Do you have ideas what collada im/export is currently missing?
> I think that carefully planned export of constrainted animations (in the
> baked form) is something that users could benefit from.
> --
> Best regards,
> Arystanbek Dyussenov
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