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wiki>Chingachgook: /* Documentation */

2009-07-28T08:39:15Z

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== Learning the basics of COLLADA ==

=== May 8th ===

In COLLADA, primitives can be presented in 2 forms: polygons as <polygons> and <polylist> and triangles as <triangles> <trifans> and <tristrips>. Ignoring line primitives for now.

Since Blender allows only quadrilaterals and triangles, I will need to find out how to convert polygons to triangles or quads or a combination of these. 

In case vertex normals are missing in a COLLADA file, they should be generated. 

In COLLADA all coordinates are right-handed by definition - this is good since Blender uses right-handed too :-). 

=== May 12th ===

How to determine if a MFace is a quad or triangle? According to exotic.c, if a face is quad then face->v4 is non-zero. 

Now I know how to use addvertlist, addfacelist functions - progress!

Arystan introduced me to operator basics and menus based on operators. 

=== May 17th ===

COLLADA DOM 

There are [https://collada.org/mediawiki/index.php/DOM_guide:_Creating_documents#The_dom.2A_classes two ways] to work with COLLADA DOM: dae* classes and dom* classes. dae* classes provide a generic string interface to data. dom* classes, in contrast, provide direct access to data, i.e. floats are stored as floats. Although dae* classes are easier to learn than dom* classes (there's only a single daeElement class vs. tens of dom* classes), to keep code compact and efficient, I'll use dom* classes as much as possible. 

=== May 18th ===

Studying a few build systems that Blender uses: make and scons.

Build with make succeded, but only release and with a few hacks. Debug build failed. Maybe later.

Built with scons before, very easy. Documentation on how to add a new library/module is available in the source tree in doc/blender-scons-dev.txt. Thanks jesterKing!

=== May 24th ===

Studying OpenCollada.

=== May 25th ===
*Coding environment prepared.
*Added "Collada Export" menu, the code is in wm_operators.c for now.

=== May 27th ===

Studying OpenCollada. It differs strongly from Collada DOM.

=== May 30th ===

Order of elements inside <Collada> (doesn't matter?) borrowed from examples in collada spec:
*asset
**required tags: created, modified - create with StreamWriter::appendTextElement
**up_axis(y up by default) - z up in Blender
*library_visual_scenes
*scene - is necessary for programs that allow only one scene
*library_geometries
*other
TODO:
*don't forget unit measurement conversions
*parenting

=== May 31st ===
Can not create <created> and <modified> with Asset class.

=== June 3d ===
prepareToAppendValues() calls another function prepareBaseToAppendValues()
which creates the following
*<source id = "">
**<float(or any other type)_array id = "" count = count * stride>
At this step I have to insert data into <float_array> with appendValues().
Next I close <float_array> and add the following
**<technique_common>
***<accessor source = "" = "" stride = "">
****<param name = "" type = ""/>
****...
***</accessor>
**</technique_common>
*</source>
with finish()

Now I know how to create <created> <modified>. It seems that
add() method creates them automatically - cool =)

=== June 5th ===
Very basic geometry exporter is almost ready! 
What is left:
*add blender's api

=== June 9th ===
Texcoords(UVs?) should be stored in <source>

== Notes for personal reference ==

*COLLADA floats are actually C++ doubles
*[https://collada.org/mediawiki/index.php/Portal:Tutorials COLLADA skinning and accessors]
*[http://www.blender.org/development/release-logs/blender-240/how-armatures-work/ How armatures work] - will be very helpful on phase-2 of this project 

== Documentation ==

*[http://www.khronos.org/files/collada_spec_1_5.pdf COLLADA 1.5 specification]

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wiki>Chingachgook: /* Documentation */

Yamyam: 1版をインポートしました