HDR and Valve

The addition of HDR into the Source engine is part of a deliberate strategy of incremental updates employed by Valve. "Efficiency goes down exponentially with time," explained Gabe. "A project that takes twice as long is considerably less efficient, because you have the complexities of different pieces not working yet. That hides bugs and makes trade-off analysis a lot more difficult. So if you have a project that's going to take five years, if you can break it up five one-year projects, you're much more likely to get to where you are going, and take fewer resources to get there."

Having taken some six years to produce Half-Life 2, Valve are looking to use the Source engine as the solid foundation onto which new technology can be added. Rather than have cool new features like HDR (and others) locked up for another 5 years and delivered in one lump that might be Half-Life 3, Valve will introduce these features one-by-one to bring these innovations to market sooner. "We'll find out whether the overhead of shipping is greater than the efficiency gain in having a narrower development focus," Gabe added.

What are the additional features to come to Source after HDR? We're not sure, and Gabe wouldn't tell us!

HDR will feature in all future Valve games, the first of which will be Day of Defeat: Source, to be released on 26th September. Yes, you read that correctly: Lost Coast will not be the first HDR release from Valve. Granted, this goes against earlier statements from the company, but according to Marketing Director, Doug Lombardi, the two releases are so close together that they are essentially considered as one, internally. No official release date has been set for Lost Coast, but you can expect it to closely follow DoD: Source's release at the end of this month.

The next title to feature HDR will be the first official expansion to Half-Life 2, titled Aftermath. Again, Valve were a little defensive in discussing a target release date, but they are hoping for November, and it is certainly expected before Christmas - the number one sales period of the year.

HDR and Games

To date, what has been touted as 'HDR' in games such as Far Cry is pretty much just a single feature called Blooming: where the light from a bright source spills over the edge of an object, obscuring it from view. The exact featureset that makes up HDR varies within the game industry, so Valve have made a list of what they think is important for HDR. This featureset includes Blooming, HDR Skyboxes, HDR Cube maps, HDR light reflection and refractions and many more.

If you are not already familiar with what these terms mean, please take a minute to read our Half Life 2: Lost Coast HDR overview for an explanation of all the new terminology and example screenshots of all the new features.

While guys like Paul Debevec first worked on HDR by compositing multiple single images of differing exposures into one combined HDR image, Valve are now producing the same effects of HDR in real-time with hardware acceleration. "This is cutting edge technology... when you're on the cutting edge, you can expect to bleed a little," Chris Green joked.

The coding team at Valve certainly sweated blood on getting HDR right for Source: in development since 2003, they went through no fewer than four different approaches to the HDR puzzle. Each method had pros & cons, so while one provided the overbright detail needed for blooming, its performance was "so-so" and it broke Multi-Sample Anti-Aliasing (MSAA). As cool as HDR is, Newell was adament that users would not have to sacrifice the ability to run AA in order to gain access to HDR.

By the fourth interation, the lads had cracked it: MSAA worked; it worked on all DX9 hardware, with reasonable performance on even a Radeon 9600; indeed the performance was the best of the four methods, with only a small performance hit over Half-Life 2's LDR solution.

To clarify, then: the HDR works on Shader Model 2 and Shader Model 3 hardware, and you can run it with anti-aliasing on.