I'm trying to enable anisotropic filtering in DirectX 9 and it seems to be a fairly straightforward process. However, when I enable and disable the filtering, it makes 0 difference on the texture quality when viewed at an angle, they still look awful. Is there a step I'm missing? d3ddev->SetSamplerState( 0, D3DSAMP_MAXANISOTROPY, 16 ); d3ddev->SetSamplerState( 0, D3DSAMP_MIPFILTER, D3DTEXF_ANISOTROPIC ); d3ddev->SetSamplerState( 0, D3DSAMP_MAGFILTER, D3DTEXF_ANISOTROPIC ); d3ddev->SetSamplerState( 0, D3DSAMP_MINFILTER, D3DTEXF_ANISOTROPIC );

Does your card support it with that MAXANISOTROPY level?

It's a GeForce 7900 gs. In all the games I play it supports x16 filtering

If you're using shaders and not fixed function, the sampler states in the shader might be overriding your SetSamplerState().

Anisotropic Filtering only makes sense for the MINFILTER sampler state, in fact I think the D3D debug runtimes will give you a warning if you set it for the MIPFILTER sampler state. When minifying a texture, anisotropic filtering takes into account multiple samples to improve the quality of textures that are viewed at an angle and so stretched along one axis. It doesn't make sense as a MIPFILTER and although D3D seems to support anisotropic filtering as a MAGFILTER, I'm not sure what that's supposed to mean and I haven't seen any hardware that supports it.

The effect is quite subtle but should be noticeable if you switch back and forth with the same scene, providing the textures you are viewing are being minified and not magnified. Have you tried debugging your scene in PIX to verify that the sampler states are set correctly for the draw call you're interested in?

Maybe check out the driver panel as well. To allow the app to choose the anisotropy, the corresponding bar in the NV panel must be grayed.