metal-cpp VS Open-Source Vulkan C++ API

My understanding is the proliferation of “XYZ-cpp” AI frameworks is due to the c++ support in Apple’s gpu library ‘Metal’, and the popularity of apple silicon for inference (and there are a few technical reasons for this): https://developer.apple.com/metal/cpp/

This is basically also what the "official" C++ API for Metal does (https://developer.apple.com/metal/cpp/), it's an automatically generated bindings wrapper which calls into ObjC runtime functions.

I also dabbled a bit with this idea by parsing clang AST-dumps of macOS system headers:

https://github.com/floooh/objc-ast-experiments

Unfortunately this is very brittle, and also broke on ARM CPUs, I guess the shim code needs some ABI adjustments (famously, objc_msgSend has multiple "ABI shapes": https://www.mikeash.com/pyblog/objc_msgsends-new-prototype.h...).

There's official C++-interface: https://developer.apple.com/metal/cpp/

It doesn't matter if the project driven by Microsoft or not, the cat (of automatically generated language bindings) is out of the bag. E.g. Zig is using the same approach without being an official MS project: https://github.com/marlersoft/zigwin32, and Apple has an automatically generated C++ API for Metal (https://developer.apple.com/metal/cpp/).

In the future, the question won't be "what language do I need to learn to code on this platform", but instead "are there language bindings for my favourite language".

this? https://developer.apple.com/metal/cpp/

Doesn't it just use objc/runtime.h and if anything is missing you can just add your custom api calls?

Metal has C++ bindings (which cover a full app lifecycle so you don’t have to touch Objective-C/Swift at all) but they’re based on the Objective-C memory model. There are some helper structs mimicking shared pointers, but you’ll still need to understand the basics of how an autorelease pool is used to avoid memory leaks and/or bad access crashes.

On https://developer.apple.com/metal/cpp/ check Foundation folder and all those nice Object::sendMessage().

It might be useful to maybe look at the Vulkan.hpp examples since you can do the same in about 200 lines of code. https://github.com/KhronosGroup/Vulkan-Hpp/blob/main/samples/15_DrawCube/15_DrawCube.cpp

Wow that library looks amazing, I'll definitely be using it. Bonus that it's official from the Khronos Group. https://github.com/KhronosGroup/Vulkan-Hpp

Even auto-generated c++ wrappers like vulkan-hpp require lots of manual maintenance.

Ultimately I went with vulkan.hpp RAII bindings, even though that way also has some learning curve and I couldn't find any documentation other than the RAII programming guide. It's great for getting started, but could use a complementary auto-generated API doc. There are also decent programming samples, which really suck for getting started, but otherwise do a good job of presenting concepts they focus on. Putting the available resources together I was able to get a project going in two weekends.

This is exactly how the official Vulkan C++ API, Vulkan-Hpp does it. For the precise example mentioned in the blog post:

Or the vulkan.hpp RAII samples would be a good place?

For a real-life example: consider the vk::raii namespace of Vulkan-Hpp, where the developers have posted examples. The vk::raii::su namespace has a bunch of free functions that one might think are associated with a Vulkan instance/object (in fact, the Vulkan Tutorial does implement them as member functions), but they are much nicer when used as pure functions. It keeps the class/struct definition itself nice and clean.

final c++17 draft (N4659) first post-publication draft after c++20 (N4868) vulkan-structs.hpp (containing the vk::ImageCreateInfo definition) VkImageCreateInfo struct