About Texture Coordinate Transformations

Direct3D devices can transform the texture coordinates for vertices by applying a 4×4 matrix. The system applies transformations to texture coordinates in the same manner as geometry, and any transformations that can be communicated in a 4×4 matrix—scales, rotations, translations, projections, shears, or any concatenation of these—can be applied.

Devices that support hardware-accelerated transformation and lighting operations (TnLHAL Device) also accelerate the transformation of texture coordinates. When hardware acceleration of transformations isn't available, platform-specific optimizations in the Direct3D geometry pipeline apply to texture coordinate transformations.

Texture coordinate transformations are useful for producing special effects while avoiding the need to directly modify the texture coordinates of your geometry. You could use simple translation or rotation matrices to animate textures on an object, or you might transform texture coordinates that are automatically generated by Direct3D to simplify and perhaps accelerate advanced effects such as projected textures and dynamic light-mapping. Additionally, you might use texture coordinate transforms to "reuse" a single set of texture coordinates for multiple purposes (in multiple texture stages).

For more information, see Using Texture Coordinate Processing.