Direct3D11 related stuff

[DragonJoker]

Hi,

While implementing a library to wrap vulkan around Direct3D 11, I've noticed some very painful missing things in D3D11, that are mandatory in Vulkan :

• Support for binding ranges of a constants buffer (UBO) is missing in D3D11 on some GPUs (even though the feature is supposed to be emulated, it is effectively missing).
• D3D11 does not support copy from GPU buffer to GPU texture at all, which is very painful, especially when you work with staging buffers.

Are those things worth integrating to Vulkan-Portability ?

[kvark]

@DragonJoker Given that Windows 7/8 and below are already out of "mainstream support" in Microsoft terms, and Windows 10 supports D3D12, the group initially decided that D3D11 is not a first tier target. That means that we aren't considering D3D11 limitations when defining the spec, and possible implementations would need to rely on other mechanisms for communicating their capabilities.

FWIW, gfx-portability also has a D3D11 backend in development. It's not nearly as tested as the Metal one, but perhaps it could save you some time.