I would love OpenGL c++ course. There are many course in it on internet sadly. It is not the easiest thing to understand but very powerful and must know for anyone interested in graphics
Can we open a new ticket for OpenGL ? Also since GameDev.tv is supporting Godot so much, an openGL course will facilitate in making potential contributors for Godot Engine.
As Apple have now dropped OpenGL I believe that Vulkan should be used as Vulkan has some wrappers that go from Vulkan to Metal.
Of course there is always an argument to keep native to each OS, ie DX for Windows, Metal for Apple OS and Vulkan for Android