Chrome, Opera pass Epic Citadel demo's Web graphics test

Two new browsers have followed Firefox with support for the Web-based 3D gaming engine. But Chrome and Opera don't use Firefox's asm.js technology approach.

The Epic Citadel demo of Unreal Engine 3 running in a browser using high-speed JavaScript and WebGL.

Chrome and Opera have become the first browsers to match Mozilla Firefox's support for Epic Games' Unreal Engine 3 and the Web-based Epic Citadel demo that's built on the 3D graphics technology. The demo's computing challenges include 3D graphics covered with 2D textures, rustling leaves, flowing water, reflective stone floors, lens flare, and shadows and other lighting effects.
Mozilla and Epic Games demonstrated the advanced Web programming in March using a combination of Mozilla technologies: Emscripten that converts C or C++ software into JavaScript, and asm.js that can run a specialized subset of JavaScript much faster.
Mozilla has been trying to drum up support for asm.js, but Chrome and Opera used their own JavaScript technology. (Opera Software, earlier this year, shifted away from its browser engine, adopting Chrome's and benefiting from Google's investment in the software.) The Epic Games demo also uses the WebGL standard for 3D graphics, which Chrome, Mozilla, and Opera all support.

Epic Games added Chrome 31 and Opera 18 to its Unreal Engine 3 supported browsers list. Martin Best, the product manager of games at Mozilla, noted the rival browsers' achievement in a blog post Tuesday.
The new browser support is notable, given the push toward Web programs that run on any machine with a browser -- cross-platform flexibility that has big advantages over writing native code that only works on iOS, Windows, or some other specific operating system. But the maturity and consistency of Web programming still leave a lot to be desired, especially for complicated, performance-intensive Web apps.
Mozilla and Google got their Unreal performance with significantly different approaches. Asm.js uses a technology called ahead-of-time (AOT) compilation for its performance boost, with the Web app sending a "use asm" hint to the browser to trigger the technology. Compilation is the process of converting human-written source code into machine language that a computer can execute. AOT compilation means the browser can build an optimized version of the software in advance.

The Epic Citadel demo of Unreal Engine 3 running in a browser using high-speed JavaScript and WebGL.

But Chrome uses a different approach with its V8 JavaScript engine called just-in-time (JIT) compilation that's standard nowadays for most Web sites and Web apps. The JIT approach means the browser compiles the JavaScript, monitors how it runs, and optimizes with new compilation as it goes.
Google likes its approach because improvements to the JIT can mean all JavaScript across the Web gets faster, not just what's specifically created to take advantage of asm.js.
Google's "V8 people seem to want to JIT-optimize harder, not process 'use asm,'" said Mozilla Chief Technology Officer Brendan Eich, but he's not convinced the performance will catch up to AOT compilation. In his experience, Unreal Engine 3 on Chrome shows more "jank" from pauses triggered by recompilation and Firefox is faster to start running the software.
"Yet they do well," Eich said, praising Chrome's virtual machine that runs the JavaScript programs. "V8 is a formidable JIT'ing virtual machine."
In my tests of the two, Chrome showed a higher frame rate on a 2012 Retina-equipped MacBook Pro. Firefox Nightly version 28.0a1 (2013-11-26) showed 52.4fps, but Chrome 33.0.1712.4-dev ran at 59.8fps.
Both versions sent the CPU fan whirring, though, so there's still work to be done.

Update, 11:24 a.m. PT: Adds comment from Google.

The Epic Citadel demo of Unreal Engine 3 running in a browser using high-speed JavaScript and WebGL.