Headers matching 1.0.26

See https://khronos.org/registry/openxr for the specification's changelog. Some improvements in the generation were required for this updated spec version (specifically new vendor extensions in it). The overall structure is unchanged, however.

What's Changed

• Fix build due to OpenXR-SDK-Source change, etc. by @KiruyaMomochi in #35
• Improve-defaultable by @rpavlik in #36
• Non-nullable-atoms by @rpavlik in #37
• Cleanup by @rpavlik in #38

New Contributors

• @KiruyaMomochi made their first contribution in #35

Full Changelog: release-1.0.21...release-1.0.26

Headers matching OpenXR 1.0.21

See https://khronos.org/registry/openxr for the specification's changelog. Since the last tagged release of this repository, a large number of improvements have been made, stabilizing it somewhat and splitting it into multiple mostly-independent header files.

Header matching OpenXR 1.0.10

Use with the headers from OpenXR 1.0.10: https://github.com/KhronosGroup/OpenXR-SDK/tree/release-1.0.10/include/openxr