> Each RGB image data block is encoded according to the BC1 formats, with the exception that the two code bits always use the non-transparent encodings. See: * https://www.khronos.org/registry/DataFormat/specs/1.3/dataformat.1.3.html#s3tc_bc2 * https://docs.microsoft.com/en-us/windows/win32/direct3d9/textures-with-alpha-channels
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