Friday, April 02, 2010

Quake II in HTML5 -- What does this really mean?

Now that we've finally been able to push our port of Quake II to the browser public, it's time to discuss the questions "what's the point?" and "what does this mean for the future?".

Let me begin with a tweet I saw last night, which neatly summarizes a very salient point:

Not sure if the best endorsement of JS engine speed in 2010 is ports of games from 1997...

http://twitter.com/tberman/status/11446377136

Well said. We should be setting the bar higher than this. The choice of Quake II was mainly predicated on the fact that a Java port already existed, and this was just a 20% project (more like -5%, actually -- nights and weekends for the most part). I'm pretty certain Quake III would have ported just as easily (perhaps more easily, as it was written specifically for hardware acceleration and likely leans on the hardware a little more).

So then there's the fact that it's running at frame rates about a third of what's possible on the same hardware in C (or on the JVM, for that matter). There are a few reasons for this:

  • There are inefficiencies still to be worked out in WebGL implementations, especially the expensive frame buffer read-back on Chrome.
  • There are things being done in Javascript that really ought to be done in vertex shaders; this especially applies to things like model animation interpolation, which is a nasty hot spot in the Javascript code that could easily be pushed to the shader.
  • There are some things, such as dealing with packed binary data structures, that are incredibly inefficient in Javascript (and I mean something like 100x slower than JVM or C code). This can be largely mitigated through better APIs, such as the Khronos Group's Typed Arrays spec.
  • This code is fairly idiosyncratic, having been ported from straight C, and exercises some code generation paths in the GWT compiler that could be better optimized (using lots of small arrays, and lots of static methods, still needs some work).

I would be willing to hazard a guess that we could easily get another 30% out of the frame rate with relatively minor tweaks. If the game were written from the ground up to work with web technologies, it would likely be twice as fast on any reasonable metric (frame rate, startup time, etc.). That's an extremely rough estimate, but I'd be willing to bet on it.

So back to our original question. What's the point? What this code currently proves is that it's feasible to build a "real" game on WebGL, including complex game logic, collision detection, and so forth. It also did an excellent job exposing weak spots in the current specs and implementations, information we can and will use to go improve them.

Now if I were starting with a plain C code base, I would most likely prefer to port it using a technology like NaCl -- that's what it's for. But while it's not feasible to actually ship games on WebGL yet (it will be a while before it's widely deployed enough for that), one can envision a world where game developers can deploy their games as easily as we currently deploy web pages, and users can play them just as easily. And that's a pretty damned compelling world to imagine.

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