It's there only to create the instance right now. Not using it to test
instance-level functionality right now as we'd be only working around it
anyway.
Otherwise I'd need to duplicate that for clang-cl, mingw and so on. It's
enabled only on MSVC 2019 and newer, because I don'r really care about
older versions -- those are mainly for compatibility with existing code,
and Vulkan is not existing code yet.
It's not using Android's native Vulkan library because that's only since
Android 24 and emulator for that version doesn't even start. So we use
our own minimal driver instead.
On Ubuntu, because SwiftShader Vulkan doesn't compile on GCC 4 (or 5)
anymore, we use 4.8 on 16.04 for compile-test against libvulkan-dev and
18.04 for render-test with SwiftShader.
On Mac, because we want to work with both MoltenVK and Vulkan Loader, we
compile-test against MoltenVk in the generic "all build" and render-test
against SwiftShader on a new, Vulkan-specific build. That requires us to
supply our own loader as well -- apparently no such thing is on
Homebrew, which is kinda silly (doesn't anybody do real Vulkan work on
this crazy platform?!).
Version query. Such a simple and obvious thing and because they forgot
to add such function to Vulkan 1.0, the only three possible ways to
retrieve a version retrieval function are:
1. with a static constructor that could make a library crash even before
main() is reached if the driver is *extra* shitty
2. with a init() function that would cause race conditions if ever
called from multiple threads (which of course can happen because you
need to know instance version in order to use the correct function
pointers and route pNext fields)
3. with a init() function that internally uses std::mutexes and
std::call_once and <functional> and atomics and whatnot and thus
takes longer to compile than the rest of the engine
Approach 2 chosen originally but the race condition countermeasures
turned out to be extra annoying to use, so switched to approach 1 now.
No need to use contractions, inverseRayDirection is okay because nobody
needs to type it anywhere. Also no need for the `ones` vector in the
test, Float/Vector3 works as well.
Such as telling people Sdl2Application is not available on Android, or
that EmscriptenApplication needs WITH_EMSCRIPTENAPPLICATION enabled in
order to be built and installed.