[ll][WIP][Postponed] Vulkan: Add MoltenVK support

[davll]

In order to run Vulkan on macOS/iOS, we should do the below:

1. update Ash to support MVK extensions
2. create surface from UIView / NSView

TODO

• Compile
• Test

Current Status

Failed to run example/hal/quad... :(

[mvk-info] MoltenVK version 0.18.2. Vulkan version 1.0.51.
[mvk-info] GPU device NVIDIA GeForce GT 750M supports the following Metal Feature Sets:
	OSX GPU Family 1 v2
	OSX GPU Family 1 v1
[mvk-info] GPU device Intel Iris Pro Graphics supports the following Metal Feature Sets:
	OSX GPU Family 1 v2
	OSX GPU Family 1 v1
AdapterInfo { name: "NVIDIA GeForce GT 750M", vendor: 0, device: 0, software_rendering: false }
AdapterInfo { name: "Intel Iris Pro Graphics", vendor: 0, device: 0, software_rendering: false }
[mvk-info] You require a license for the MoltenVK Vulkan Core feature set. Reverting to evaluation mode.
Segmentation fault: 11

It seems that somewhere in the Rust runtime has failed to do core::ptr::drop_in_place<alloc::boxed::Box<Any>>.

UPDATE:

The segmentation fault disappears when I commented out swapchain creation code.
functor.create_swapchain_khr
I'll investigate there later.

How to test

Download and install libMoltenVk.dylib to $HOME/.local/lib

cd examples/hal/quad
DYLD_LIBRARY_PATH=$HOME/.local/lib RUST_BACKTRACE=1 cargo run --features vulkan

Run debugger

DYLD_LIBRARY_PATH=$HOME/.local/lib RUST_BACKTRACE=1 /Applications/Xcode.app/Contents/Developer/usr/bin/lldb target/debug/quad

[davll]

I don't think it is worth to keep developing and fixing the PR, and therefore decided to stop working on it. Hope someone can pick it up and continue on it.

[kvark]

@davll is this feature desirable? Given how close our Metal backend now to be conformant, I wonder what value does MoltenVK integration bring to our Vulkan backend.

[davll]

OK, I think it should be closed due to no activity.