User:Chingachgook/Gsoc2009/Diary

From BlenderWiki

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 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

• Invalid language.

  You need to specify a language like this: <source lang="html4strict">...</source>

  Supported languages for syntax highlighting:

  4cs, abap, actionscript, actionscript3, ada, apache, applescript, apt_sources, asm, asp, autohotkey, autoit, avisynth, awk, bash, basic4gl, bf, bibtex, blitzbasic, bnf, boo, c, c_mac, caddcl, cadlisp, cfdg, cfm, cil, clojure, cmake, cobol, cpp, cpp-qt, csharp, css, cuesheet, d, dcs, delphi, diff, div, dos, dot, eiffel, email, erlang, fo, fortran, freebasic, fsharp, gambas, gdb, genero, gettext, glsl, gml, gnuplot, groovy, haskell, hq9plus, html4strict, idl, ini, inno, intercal, io, java, java5, javascript, jquery, kixtart, klonec, klonecpp, latex, lisp, locobasic, logtalk, lolcode, lotusformulas, lotusscript, lscript, lsl2, lua, m68k, make, mapbasic, matlab, mirc, mmix, modula3, mpasm, mxml, mysql, newlisp, nsis, oberon2, objc, ocaml, ocaml-brief, oobas, oracle11, oracle8, pascal, per, perl, perl6, php, php-brief, pic16, pike, pixelbender, plsql, povray, powerbuilder, powershell, progress, prolog, properties, providex, purebasic, python, qbasic, rails, rebol, reg, robots, rsplus, ruby, sas, scala, scheme, scilab, sdlbasic, smalltalk, smarty, sql, systemverilog, tcl, teraterm, text, thinbasic, tsql, typoscript, vb, vbnet, verilog, vhdl, vim, visualfoxpro, visualprolog, whitespace, whois, winbatch, xml, xorg_conf, xpp, z80

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