How to get a raw pointer of vk::Device?

[iddm]

I have a ash::vk::Device object, and I need to get a real vulkan *mut vk::Device. I see only the Handle trait, but the values there return an u64.

I can only think of this hack:

fn main() {
    let number = 5u64;
    let pointer = std::ptr::null_mut::<u8>();
    let pointer = unsafe { pointer.add(number as _) };
    let vk_device_ptr: *mut ash::vk::Device = pointer.cast();
}

Regardless of the answer, can ash include such a possibility of returning native typed pointers to the user instead of just integers?

[MarijnS95]

PFN_vkCreateDevice also takes a *mut vk::Device, this already works by taking a borrow (which implicitly derefs to a raw pointer) to the #[repr(transparent)] vk::Device which is a *mut u8 under the hood.

ash/ash/src/instance.rs

Line 364 in a40ddee

&mut device,

ash/ash/src/vk/features.rs

Line 187 in a40ddee

p_device: *mut Device,

But the example/hack contradicts your request. What do you need this for, can you show an example of the API in question?

and I need to get a real vulkan *mut vk::Device

What is meant here by "real"? Handles are typically passed by value (except for getter cases like vkCreateDevice() demonstrated above) and are pointer typedefs to declared (but undefined!) structs: https://registry.khronos.org/vulkan/specs/1.3-extensions/man/html/VK_DEFINE_HANDLE.html

[iddm]

That means that I had bindgen bindings to a c library which accepted a vk::Device*, so I couldn't work with just some transparent handle because of the types. I had to actually convert it to a pointer of the target type. So, thanks to the types being typedef as a pointer, I was able to calculate the offset myself. the way I did above (still not sure it is correct, though, but everything seems to work so far). So, it would be nice to have a trait and implement it for all these types to get a raw pointer to these objects, without doing what I did every single time.

[MarijnS95]

There is no API to add here, afaik. If you have an ash::vk::Device, you just take a borrow of that and let the compiler coerce that to a pointer, so that it becomes *mut ash::vk::Device which is equivalent to a pointer to a Device handle?

Can you share the library, header, and/or bindgen result so that we can take a look at what you need? Can you share what bindgen is typedef'ing that vk::Device to?