Graphics Texture Mapping

When performing anisotropic filtering when sampling a texture to provide an output sampled texture value for use when rendering an output in a graphics processing system, an anisotropy direction along which to take samples in the texture is determined by determining X and Y components of a vector of arbitrary length corresponding to the direction of the major axis of an assumed elliptical projection of the sampling point for which the texture is being sampled onto the surface to which the texture is being applied, and then normalising the determined X and Y vector components to provide X and Y components for a unit vector corresponding to the direction of the major axis of the elliptical footprint of the sampling point to be used as the anisotropy direction along which to take samples in the texture.