For a while now, I've been working with XNA for game design and development (although only for personal use ATM.) Overall, I'm a major fan of XNA itself, and it's overall "feel." However, due to the fact that:

1. XNA seems to have a lack of support (no Metro support, no updates since 2010, etc.)
2. I plan to try and get a job in the game development industry, and due to C++'s dominance, being more familiar with it would be very useful
3. XNA only supports Windows (non-Metro) and Xbox 360, while I am interested in Mac and (to a lesser extent) Linux support.

I've been trying to shift over to C++ as my main language. However, I do not want to focus on learning raw DirectX/C++ at this time, so I've been looking for a higher level C++ API (something about the same level as XNA, although something a bit more low-level would be fine) with a feel similar to XNA. So, for someone switching from C#/XNA to C++, what would my best choice(s) be for API's similar to XNA, although unmanaged and running on C++?