(KTX). The KTX file format is straightforward and designed to be easy to
use in OpenGL.
http://www.khronos.org/opengles/sdk/tools/KTX/file_format_spec/http://www.khronos.org/opengles/sdk/tools/KTX/
The attached plugin can read:
* 1D, 2D, and 3D textures
* uncompressed and compressed images
* mipmapped and non-mipmapped textures
* little-endian and big-endian files
* textures from files as well as seekable istream objects
It does not handle:
* array textures (not supported by the ReaderWriter API)
* cubemap textures (not supported by the ReaderWriter API)
* the "KTXorientation" key-value pair; support could be added later (see
the file format spec for more information)
* non-seekable istream objects (would require more complicated memory
management)
"