Thursday, May 22, 2008

bike accident

I got side-swiped by a car Tuesday. Only injuries are some scraped skin and sprained wrist (I'm either really lucky or all too experienced in surviving bike accidents), but the latter has dramatically slowed by dev pace due to having to type with only one hand.

The sprain is mending well and i should be able to do light stuff (like typing) with it this weekend, provided I keep it immobile.

In other news, bump mapping is working again, but our lacks proper normals, texcoords, and tangents. If anyone is willing to spend an hour or two working out the calcs for these please get in touch.

Tuesday, May 20, 2008

hacking at 3am, seeing rainbows

There are some real advantages to hacking into the wee hours of the morning, this gem of a screenshot is one of the best of late.

Thing is, I'm sitting here after refactoring several hundred lines of code and fixing two typos that was causing our normalisation cubemaps to be bugged, staring at this window, and unable to understand why.

The rainbow effect is obviously from the normalisation cubemap, a data construct that maps tangent-space bumpmaps to object-space on the video card (without shaders). I just can't determine at this late hour why it's showing up instead of rendering the bumpmap as it used to.

I'm sure it'll make much more sense after 8 hours sleep. In the meantime, enjoy the screenshot, or compile PySoy from subversion and run yourself!

Saturday, May 17, 2008

Mesh code refactoring

I spent most of the day fixing, shifting, folding, documenting, and otherwise refactoring soy.models.Mesh and it's related datatypes and atoms. I'll likely spend most of tomorrow finishing this up.

In short, the render process we used was crude, lacked some really easy features, looped through 6 different classes for each Mesh (Mesh, MaterialList, Material, Texture, FaceList, VertexList) and had data management code in these plus the two related atom classes (Face and Vertex).

In short, not only was the code difficult to grok (even for me and I wrote much of it) but was slower that need be and increasingly difficult to expand. Game engines need both rendering speed (fps) and easy expandability, so this is a high priority ticket.

The new structure moves all of the actual Mesh data into the Mesh objects themselves; MaterialList is gone (to be replaced by MaterialDict later), FaceList and VertexList will now only store a reference to their parent Mesh to draw data from.

I'm going to be centralizing data management functions in Mesh as well, so the atoms can be much simpler and we can actually talk about optimizing the VBO layout. We'll also be doing dynamic passes, based on how many textures/pass a GL implementation supports, and supporting more textures targets (ie, specularity, emissive)

Again, sprint via IRC this weekend complete with remote peer programming via Gobby. Join us in #PySoy on

why can't XMPP keep their website up?

Several times this month I've found, the organization responsible for the Jabber protocol and it's many extensions, non-responsive. Their site has been down for at least 7 hours tonight, the longest yet (to my knowledge).

For our purposes I'll be mirroring their XEP's on as soon as they're back up. It's seriously frustrating to be working on this when the documents you need are often unavailable.

If anyone knows of an existing mirror we could use, please reply to this posting.

Friday, May 16, 2008

some real progress toward beta-3

With Pyrex 0.9.8 released yesterday, including a number of key changes we needed to move forward, we're back in action for PySoy belated Beta-3 release.

The new forward declarations are a bit kludgy (example), and I don't think it'll be very maintainable in the long term. I think changing a class's inheritance should require editing one file, not two (the .pxd) or more (every .pxd that uses it).

It works for now, until we can wipe out the entire include/ directory, and to be fair it's only so cumbersome due to PySoy's size and how the classes are interconnected.

The nogil allowance for cdef methods is a massive step toward stomping out the multicore race conditions. One of the developers testing just the fixes to soy.bodies noticed the examples often running longer than before, though there's a lot more cleanup to be done before this is package-wide.

One of the roadblocks I hit is the nogil fix can't be used with our Children class, which stores pointers to Python objects of the same type and uses those pointers (through a typecast) to access their cdef methods in a for loop.

While our usage is GIL-safe, the current version of Pyrex still wants to throw in an INCREF just to be extra-cautious, which makes it not. I've let Greg know about this, we'll see if it can't be fixed soon.

In the meantime, I've called for an IRC sprint this weekend for the pending cleanup, refactoring, documentation, and testing that needs doing before beta-3. Join #PySoy on if you want to pitch-in!

Tuesday, May 13, 2008

Building a better Pyrex - part 1

With our recent decision to drop the Pyrex codebase and start from scratch, we find ourselves repeating a process from 2 years ago;

When PySoy first forked off of Soya, we had a small list of things that needed to be fixed based on our negative experiences working with that project. The API needed to be cleaned up, pydocs added, Shape needed to be mutable and implemented with vertex arrays or VBOs rather than display lists, etc.

As we worked on it, that list grew longer, including rewriting large parts of the codebase, until we found ourselves at a point where starting over would be more expedient. Of course now there's little doubt that was a good move, learning from both Soya's mistakes and our own failed early attempts we now have a pretty rocking architecture.

The first and most foundational change we're making from Pyrex, as previously stated, is in the lexical scanner and parser. Both Pyrex and Cython are based on Plex, which was Greg's answer to processing a Python-like language.

In contrast, we'll be using Python's own tokenize module for our lexical scanner and an ASDL-based parser akin to the parser used in Python 3.0. We're extending Python.asdl with cdef, ctypedef, cimport, cinclude, etc.

This way we have less code to debug and a solid foundation to start with. With lexing and parsing almost "for free" we'll be able to focus on the important bits and get the platform able to support the kind of features we need quickly.

We've also reached a rough consensus on the following syntax changes from Pyrex:
  • unicode, generators, decorators, etc will be supported
  • all custom for syntaxes dropped in favor of Python's standard
  • with nogil: replaced with full with support
  • special methods will always have self as first argument (ie, both __sub__ and __rsub__ used)
  • cinclude added for direct C header parsing

There's more to come, which I'll post in additional installments as work progresses on this project. works with

Greg fixed the latest bug that caused PySoy to raise a dict assignment error on import with 0.9.7.

Pyrex was released a few hours ago with this fix, and I've updated to work with either or >=

Beta-3 is still blocked by the multicore race condition caused by redundant incref/decref calls on Python arguments to class methods in this latest version of Pyrex.

Monday, May 12, 2008 now requires EXACTLY Pyrex

16:02 < maacl> import soy
16:02 < maacl> File "LoopThread.pym", line 51, in
16:02 < maacl> TypeError: 'dict' object does not support item assignment
16:03 < Arc> from threading import _active, _active_limbo_lock
16:03 < Arc> self._active = _active
16:03 < Arc> [...] and line 51:
16:03 < Arc> self._active[self._threadID] = self

I'm not going to even look into this further. Pyrex 0.9.7, for a reason I'm not going to even contemplate, raises an error about dict item assignment on the last line. None of us use it due to it's barfing of depreciated lines for all our for statements, but this brave tested did and reported the problem today.

I just committed an update to that fails when any Pyrex version besides is used.

Sunday, May 11, 2008

subversion vs git

I stayed up late last night working to install a shared git repository for the Pyrex replacement project. First of all, copious thanks to johnw and Ilari on #git for their help on this.

I'm very much an enthusiast of Trac, it's an excellent engine for project websites and has all the essential tools, builtin and via plugins, that any project should need. Ok, so there's a few things a project could need that isn't already written, but new plugins are easy enough (it's all Python, after all).

As such, I like to leave user administration to Trac, and it maintains a .htusers and .access file local to each project for that purpose. Likewise, for SVN, we use WebDAV on Apache, whereas the ssh+svn method would require adding those users to the local system or PAM hacking.

Thus, the most direct path would seem to install GIT via WebDAV and run it from there. As Ilari pointed out, GIT's DAV has many problems over SVN, from lockups to a failed push sometimes corrupting the shared repository. I tried anyway, with hours of help from joshw, and at 5am I had to throw in the towel. I'm sure it's possible, but not with my current lack of GIT knowledge.

The other available solutions could work, but first I'd want to write some new Trac plugins for accepting developer ssh keys and using these on the backend to govern access or figure out the PAM configuration for .htusers to have restricted SSH access for GIT pushes.

There are certainly advantages to GIT, but server setup difficulty and added complications for Windows developers leads me to sticking with subversion servers with git-svn client-side for now.

Saturday, May 10, 2008

a radical redirection

We've been at a deadlock for a few weeks now, our previous coding pace has turned into a lot of contemplation and side discussions about the greater issues with the PySoy codebase.

I think we have a roadmap forward, or enough of one to post these in a blog entry:

First, PySoy 1.0 will not be released until after Python 3.0 this Fall, and it would be pointless to continue developing with 2.x in target. Python 3.0 also has a large number of useful changes for our project. Our target platform should therefore be 3.0 (and it's alpha/beta's for now).

Second, with the release of Pyrex 0.9.7 Greg has, once again, introduced a major language change (the "for" statement) without even soliciting input from the community. This has sealed the deal for us, even if our immediate issues are fixed we cannot continue to subject ourselves to a language that changes in incompatible ways between 2 micro versions (0.9.6 -> 0.9.8, when the old syntax will not be supported).

We earlier started a Cython variant to support PySoy's codebase, but given recent developments in their community, the timelines of our projects, and their choice to stick with Python 2.x for now, we're moving forward on a Pyrex replacement written from scratch and targeting Python 3.0.

We're going to use a similar language style to Pyrex, Greg certainly had some good ideas, and will keep language porting in mind, but there will be changes. We will also not be using any of his code including his Plex module, Pyrex and Cython's lexical analyzer which is the core of those packages.

PySoy Beta3, earlier aimed for release in "early Spring", has been indefinably postponed as we work on that. The subversion repository is of course open, and development can and will continue, but we cannot release until the new build system is complete.

Friday, May 02, 2008

initial impressions of Trac 0.11

Trac 0.11rc1 was released this week, marking a feature freeze for 0.11.

One of the major improvements over 0.10.4 is the Genshi template system allowing complete control over a site's HTML. For example, you can copy the default layout.html to your site's templates/ directory to remove the obnoxious "Trac" string at the end of every page's title and the other Edgewall advertising splayed all over a default Trac site.

Of course, this is also means a Trac site can be radically redesigned in structure without editing the source code. Hopefully this leads to a greater diversity in project site design.

Another major feature is ticket workflows are now customizable, allowing projects using Trac to decide how their tickets will be processed. For example, a "testing" state could be added to signify a ticket as "though to be complete, but waiting for verification".

I plan on upgrading this weekend along with a few new Trac plugins and a minor site redesign.