Remove dependency on windows.h about vulkanmemoryallocator

[res2k]

This approach can break under several circumstances:

• When vulkan_win32.h is changed and makes use of additional Windows types: they're not found.
• Those typedefs are, strictly speaking, windows.h implementation details: They may change in some future SDK update.
• There may be some other conflicts if windows.h is included before or after that bit.

While you may be able to live with the limitations, they're somewhat unsuited for a header that should work in a wide variety of projects.

[jesta88]

Yes these are the risks. Other popular vulkan libraries opted to remove windows.h anyways because realistically, this should be extremely rare (if ever, in the lifetime of a major Vulkan version) and is trivial to fix.

I understand if the owners don't see it that way though.

[res2k]

If I wanted to get rid of windows.h but keep VK_USE_PLATFORM_WIN32_KHR, I might create a wrapper header that does something like you did above, with a #define VULKAN_H_ after #include <vulkan/vulkan_win32.h> and immediately including vk_mem_alloc.h. It should give the result you desire.

If you name your wrapper vk_mem_alloc.h (with the "real" header named differently, of course) you'll even get a transparent solution.

[adam-sawicki-a]

In my opinion @res2k is right. The solution proposed is a hack and may not be reliable or future-proof. If Vulkan header includes "windows.h" then please contact the developers of Vulkan SDK with request to change that.

Many Windows applications include and use "windows.h" anyway. To speed up compilation under Visual Studio I recommend putting it in precompiled header.