(NOTE: Trilinear filtering is a patented process owned by Lockheed-Martin/Real3D but the technique has many variations and the term has become almost generic. 3dfx, for example, uses their own patented technique. NVIDIA says they are using a D3D technique called linear-mipmap-linear. - ED)

TNT is capable of single pass trilinear but not when multi-texturing. To avoid a performance hit, the hardware defaults to 'dithered trilinear' when multi-texturing. Besides true trilinear filtering, there are implementations that approximate true trilinear filtering that produce images of reasonable quality without the performance penalty.

'Dithered trilinear' does not belong to any of these 'Trilinear approximation' methods. In fact, it is little better than a bilinear filter. To date, only the Savage4 lays claim to the ability to apply two trilinear textures in a single pass. Trilinear Filtering

'Vortex Rikers' from 'Unreal', actual resolution: 800x600x32

'Trilinear Approximation' (Savage4, Direct3D renderer, trilinear turned on)

'Trilinear Dithering' (TNT2, Direct3D renderer, trilinear turned on)

'Bilinear Dithering' (TNT2, Direct3D renderer, trilinear turned off)

(NOTE: On a practicla note, this is a good example of features over function. Because NVIDIA is not actually doing trilinear filtering in this case, the game actually looks better with the 'advanced' trilinear filtering feature turned off. The game also runs better with this setting and is, in fact, what the developer has set as the default. Once again, bringing the theoritical in contact with the practical does not always bring the anticipated result. - ED)