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Compressed Texture Surfaces

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A surface can contain a bitmap to be used for texturing 3D objects. To reduce the amount of memory consumed by textures, Microsoft DirectDraw supports the compression of texture surfaces.

Note   No new callbacks have been added to support compressed texture surfaces. DirectDraw passes information about compressed texture surfaces to the driver through the existing driver callbacks.

FOURCC Description Alpha
premultiplied?

DXT1

Opaque / one-bit alpha

N/A

DXT2

Explicit alpha

Yes

DXT3

Explicit alpha

No

DXT4

Interpolated alpha

Yes

DXT5

Interpolated alpha

No

The preceding shows the five types of compressed textures that drivers should support.

For more information about the format of compressed textures, see Compressed Texture Formats in the DirectDraw SDK documentation.