Shader model wars revisited

When it was released, the game Splinter Cell: Chaos Theory supported only two DirectX shader programming models for graphics, Shader Model 1.1 and Shader Model 3.0. This was something of a curious development, because the most commonly supported shader model among DirectX 9-class graphics cards is SM2.0. Many of the game's fancy visual effects were only available on newer NVIDIA graphics cards, despite the fact that lots of other cards, including several cubic tons of Radeons, could easily reproduce those effects.

This slight has been addressed in a new patch for the game, and SimHQ has tested Shader Model 2.0 on a Radeon X800 XT versus SM3.0 on a GeForce 6800 GT. The article is worth a read, because it sheds some light on the shader model debate. However, I'd recommend ignoring their assertion that "no ATI hardware currently on the market supports high dynamic range rendering." The first real-time HDR rendering demo that I ever saw was running on a Radeon 9700, and any new ATI VPU based on that technology (virtually all of them) can do HDR rendering. ATI chips have to rely on their pixel shaders to handle floating-point texture filtering and blending, while NV4x GPUs can handle those tasks with dedicated logic. Still, as ever, SM2.0 cards can render virtually anything that SM3.0 cards can. Given the performance numbers from SimHQ's tests, the real-world differences between shader models 2.0 and 3.0 look as slight as ever.

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