Ios fix

[hakolao]

As part of my ongoing desire to also build my current project as an iOS app I discovered that iOS seems to be broken.

I am assuming that not many have been running Vulkano on iOS. So this PR is a result of a bunch of figuring out how to get an iOS app to compile and run on my iPhone 8 plus.

Error 1:

error[E0782]: trait objects must include the `dyn` keyword
  --> /Users/okkohakola/Programming/Rust/vulkano/vulkano/src/library.rs:45:44
   |
45 |         fn def_loader_impl() -> Result<Box<Loader>, LoadingError> {

After fixing above by adding dyn

Error 2:

error: cannot find macro `statically_linked_vulkan_loader` in this scope
  --> /Users/okkohakola/Programming/Rust/vulkano/vulkano/src/library.rs:46:26
   |
46 |             let loader = statically_linked_vulkan_loader!();

After fixing above by crate::statically_linked_vulkan_loader

Errors 3:

error[E0053]: method `get_instance_proc_addr` has an incompatible type for trait
   --> /Users/okkohakola/Programming/Rust/vulkano/vulkano/src/library.rs:328:13
    |
46  |               let loader = crate::statically_linked_vulkan_loader!();
    |                            ----------------------------------------- in this macro invocation
...
328 | /             fn get_instance_proc_addr(
329 | |                 &self,
330 | |                 instance: ash::vk::Instance,
331 | |                 name: *const c_char,
332 | |             ) -> extern "system" fn() -> () {
    | |___________________________________________^ expected unsafe fn, found normal fn

46  |             let loader = crate::statically_linked_vulkan_loader!();
    |                          ----------------------------------------- in this macro invocation
...
332 |             ) -> extern "system" fn() -> () {
    |                  -------------------------- expected `extern "system" fn()` because of return type
333 |                 unsafe { vkGetInstanceProcAddr(instance, name) }
    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected fn pointer, found enum `Option`

After fixing that with

        unsafe impl Loader for StaticallyLinkedVulkanLoader {
            unsafe fn get_instance_proc_addr(
                &self,
                instance: ash::vk::Instance,
                name: *const c_char,
            ) -> ash::vk::PFN_vkVoidFunction {
                vkGetInstanceProcAddr(instance, name)
            }
        }

Errors 4

// Bunch of
144 |                     win.borrow().xlib_display().unwrap(),
    |                                  ^^^^^^^^^^^^ method not found in `&Window`

Fix that with

#[cfg(all(unix, not(target_os = "android"), not(target_os = "macos"), not(target_os = "ios")))]

Error 5

41 |     unsafe { winit_to_surface(instance, window) }
   |              ^^^^^^^^^^^^^^^^ not found in this scope

Already down the rabbit hole, make one for ios... how? ... Well my eventual investigation & debugging resulted in handling iOS and MacOS similarly to wgpu seen in this PR.

I've managed to get this working nicely with resizes etc. following wgpu's approach

If you have xcode and apple developer subscription, you should be able to run bevy_vulkano_ios

There is also a simple triangle example in this branch.

And lastly, to fix create_surface_from_handle, testing that in this branch

[Rua]

There's no regressions on my end, so in principle it could be merged. But ideally someone who can test this on iOS would check it first. Is there anyone?

[hakolao]

Let me just try a couple more things today still @Rua just to be sure

[hakolao]

I added these just to make sure we're doing the same function calls master version is doing. Though I am unsure if these are necessary.

[hakolao]

This is ready now

[Rua]

I'll merge it, hopefully we can get other users to test and report any bugs.