What is pixel shading?

On 21 Oct 2005 14:37:03 -0400 PN wrote:

> I was looking for a game "Constantine"and it said that video card
> must support pixel shading.What is it?

They are little programs (written by the game developer) that run on the
graphics chip and that are executed for single pixels to define their
appearance on the screen.

Older 3D chips, that don't have that feature only allow for a pre-defined,
hard coded behaviour, meaning much less flexibility for game developers to
customize the look of their games and add visual effects.

Pixel shaders (for Microsoft's DirectX platform) first appeared in early
2001 in Nvidia's "GeForce 3" GPU. There are multiple revisions, already,
though. GeForce 3 supported rev. 1, the Radeon 8500 that appeared later in
2001 supported PS 1.1 etc (the latest revision is PS 3.0).

If your game just says "pixel shading" without specifying any version
number, I'd assume it would only require PS v1.

All of those version numbers refer to MS's DirectX. For OpenGL there have
been vendor specific extensions for version 1.x and for the latest OpenGL
version 2.0 there's a standard for a High Level Shading Language (HLSL). I
don't know how well that standard is supported by ATI, Nvidia etc.
currently, though.


HTH,

Chris