KhronosGroup/KTX-Specification

KTX file format source

Home of the KTX File Format Specification

KTX is a file format that can be used for storing GPU-ready texture data (with cubemaps, mip levels, etc). Like DDS but with more features and more formal specification. It supports Basis Universal transcodable formats and supercompression which can yield JPEG-sized universal textures. glTF will use Basis Universal textures in KTX v2 containers.

Click to see the latest published versions of the KTX File Format Specification or the KTX Fragment URI Specification from the Khronos KTX Registry (they look much better than the ersatz views provided by GitHub) or run

make

in a Unix-like environment with AsciiDoctor installed to generate the publishable specs. They are the files out/ktxspec.v2.html and out/ktx-frag.html. Everything needed is inlined.

The canonical KTX spec. text is in the file ktxspec.adoc. The canonical fragment URI spec. text is in the file ktx-frag.html.

If you have questions or comments that don't merit creating an issue such as "why did you do so-and-so?" use GitHub Discussions.

GPU texture format mappings

To ensure correct mappings from Vulkan's VkFormat to other GPU APIs, this repo additionally contains:

• JSON database (schema) with mappings to OpenGL, Direct3D, and Metal enums.
• Switch-case generator that produces 5 files with simple C-like case-return statements.

  Usage: ./generate_format_switches.rb [<out_dir>]

• Compile test of the case statements that serves as an example of use.

$Date$ keyword expansion

A few auxiliary files have $Date$ keywords. If you care about having the proper dates shown on files in your workspace, you must follow the instructions below.

$Date$ keywords are expanded via a smudge & clean filter. To install the filter, issue the following commands in the root of your clone.

On Unix (Linux, Mac OS X, etc.) platforms and Windows using Git for Windows' Git Bash or Cygwin's bash terminal:

./install-gitconfig.sh
rm TODO.md
git checkout TODO.md

On Windows with the Command Prompt (requires git.exe in a directory on your %PATH%):

install-gitconfig.bat
del TODO.md
git checkout TODO.md

The first command adds an [include] of the repo's .gitconfig to the local git config file .git/config, i.e. the one in your clone of the repo. .gitconfig contains the config of the "dater" filter. The remaining commands force a new checkout of the affected files to smudge them with the date. These two are unnecessary if you plan to edit these files.