.DDS File Format – Data layout

Pitch and level size

dwPitchOrLinearSize is unreliable, because libraries have filled it in inconsistently, so Microsoft recommends computing it:

The size of one level of a block-compressed texture is max(1, (width + 3) / 4) × max(1, (height + 3) / 4) × block size. The pitch the runtime supplies is not always the same as this, so Microsoft recommends copying a scan line at a time.

A texture with mipmaps

The main image is followed by each smaller level, down to the last. A 256 by 256 uncompressed R8G8B8 texture holds:

With compression, levels smaller than 4 by 4 pixels still take a full block: 8 bytes for DXT1, 16 bytes for DXT2 to DXT5.

Cube maps

Faces are written in the order positive x, negative x, positive y, negative y, positive z, negative z, leaving out any missing face. Each face is its main image and then its mipmaps. All faces are the same size with the same number of levels, and since DirectX 8 a cube map has all six faces.

In Direct3D 10 and later a cube map is a 2D texture array of 6 images, written with a DX10 header. An array of cube maps has arraySize cubes and so arraySize × 6 images.

Volume textures

Without mipmaps, each depth slice is written in order. With mipmaps, all slices of one level are written together, and each level has half as many slices as the one before, with a minimum of 1. A 64 by 64 by 4 volume of 3-byte pixels with all levels holds four 64 by 64 slices, then two 32 by 32 slices, then one each of 16 by 16, 8 by 8, 4 by 4, 2 by 2 and 1 by 1.

Texture arrays

With a DX10 header, array elements follow each other, and each element holds its full set of mipmap levels:

for (element = 0; element < arraySize; element++)
    for (level = 0; level < dwMipMapCount; level++)
        ...the surface...