This covers implementation of the GPUTexture abstraction for the Metal backend, with additional utility functionality as required.
Some components have been temporarily disabled pending dependencies on upcoming Metal backend components, and these will be addressed as the backend is fleshed out.
One core challenge addressed in the Metal backend is the requirement for read/update routines for textures. MTLBlitCommandEncoders offer a limited range of the full functionality provided by OpenGLs texture update and read functions such that a series of compute kernels have been implemented to provide advanced functionality such as data format conversion and partial/swizzled component updates.
This diff is provided in full, but if further division is required for purposes of code review, this can be done.
Authored by Apple: Michael Parkin-White
Ref T96261
Reviewed By: fclem
Maniphest Tasks: T96261
Differential Revision: https://developer.blender.org/D14543
Adding WITH_METAL option to CMAKE to guard compilation for macOS only. Implemented stub METALBackend to mirror GPUBackend interface and added capabilities initialisation, along with API initialisation paths.
Global rendering coordination commands added to backend with GPU_render_begin and GPU_render_end() commands globally wrapping GPU work. This is required for Metal to ensure temporary resources are generated within an NSAutoReleasePool and freed accordingly.
Authored by Apple: Michael Parkin-White, Vil Harvey, Marco Giordano, Michael Jones, Morteza Mostajabodaveh, Jason Fielder
Ref T96261
Reviewed By: fclem
Maniphest Tasks: T96261
Differential Revision: https://developer.blender.org/D14293
