[ktx2] --automipmap does not work (at least with --bcmp) about ktx-software HOT 1 CLOSED

-automipmap does not generate mipmaps. The documentation says:

        "  --automipmap A mipmap pyramid will be automatically generated when the KTX\n"
        "               file is loaded. This option is mutually exclusive with --levels\n"
        "               and --mipmap.\n"

The key here is "when the KTX file is loaded." I.e the pyramid is generated by OpenGL or Vulkan. This is indicated by setting levelCount in the .ktx2 file to 0.

Generating a pyramid within toktx is something that needs to be added and something I want. For that I would call the option --generatemipmap. I'd be happy to accept a PR to add this function.

To create a mipmapped .ktx2 file with toktx now, you have to specify --mipmap and provide each of the images on the command line or by listing the file names in a file referenced with @ on the command line. E.g.

toktx --mipmap --t2 out.ktx2 @mipfilelist.txt

Be aware that basisu_tool -mipmap option only really works for 1D or 2D images as it puts the mip levels immediately after the base image. When loading, e.g. array textures you need the images for each layer of the array of the same level together sequentially. This means we cannot simply use the basisu_encoder mipmap generation functionality.

Since --automipmap does work as intended, I'm going to close this. Please open another issue for adding mipmap generation functionality.

from ktx-software.