N64 Programming Manual Chapter 13

Restrictions

Texture Types and Modes
The following is a list of restrictions concerning the use of certain textures types in certain modes:

Point Sample
Clamp &/| (wrap | mirror) works for all texel types.

Filter
Clamp works for all texel types. Wrap t | mirror t | (clamp t & wrap t) | (clamp t & mirror t) works for all texel types.

Wrap s | mirror s | (clamp s & wrap s) | (clamp s & mirror s) works for all texel types except YUV.

Copy
Clamping is implicitly disabled for copy mode. 32-bit RGBA and YUV texel types are not supported. To copy these types, they should be loaded and copied as 16-bit RGBA type texels. When using a 16-bit RGBA type to copy a 32-bit RGBA or YUV texture, mirroring in s is not supported.

Wrap or mirror works for 4, 8, and 16-bit types.

LOD
You must put the RDP in two-cycle mode to use texture LOD.

Alignment
The texture image pointer, as defined using the gDPSetTextureImage command, must be 8-byte aligned. Additionally, each tile must be aligned according to its size. For example, 8-bit texture tiles must be aligned to 8-bit boundaries, 16-bit textures to 16-bit boundaries, etc. One exception is 4-bit tiles, which must be accessed on byte (8-bit boundaries).

Tiles
The maximum size of a tile is 256 rows (t coordinate) and 1024 texels (s coordinate) within the limits of Tmem size. It is better to always make the s coordinate the longer coordinate in terms of load performance.

You should avoid shifting coordinates left using the shift parameter of a tile unless necessary. Please see the example in Section 13.12, Applications - "Multiple Tile Effects."

Coordinate Range
The valid texture coordinate range is currently from -1024.0 to +1023.99. A total range of 2K texels across a primitive. The texture hardware can handle this full range without any noticeable loss of accuracy. For small coordinate ranges however, if given a choice of coordinates close to zero or coordinates close to 1024, slightly higher quality may result from the lower coordinates.