Add separate ExternalDependencies Xcode project.
Move external dependencies to ExternalDependencies project.
The fetchDependencies script builds external dependencies libraries into External/build.
The fetchDependencies script prepares SPIRV-Tools without preparing glslang.
MoltenVK links to pre-built external dependency static libraries.
MoltenVK includes external library headers using full relative paths.
Instead of assuming that `kMVKFormatNone` means the format is
compressed. This makes the code doing these checks more obvious and
self-documenting.
Since I changed the public MoltenVK-specific API, I also bumped the
`VK_MVK_moltenvk` spec revision.
Since a pipeline might be shared between multiple draws, but those draws
could use different textures, it isn't tenable to have a single aux
buffer shared between those draws. Instead, we'll set up constant
buffers using the `setXxxBytes()` method on the command encoder. That
way, separate draws using the same pipeline won't interfere with each
other.
This change also uses separate buffers for the vertex and fragment
shaders, since they may have different sets of textures.
Null the `sampler` field of the stored `VkDescriptorImageInfo` if the
descriptor uses an immutable sampler. That way, we won't try to
double-free a sampler.
Retain immutable samplers when the set is created. Release them when the
set is destroyed.
In which I am proved wrong again. While Metal indeed won't assert if the
pixel formats don't match, the results of attempting such a copy are...
mixed, to say the least. Sometimes, nothing is copied at all. Other
times, pixels are copied in weird ways that don't seem to conform at all
to expectation. (This is most apparent in the output of the CTS's image
copying tests.) It's best, then, to ensure that the source and
destination have the same format.
Unfortunately, in the process of writing this, my fears regarding not
being able to make uncompressed views of compressed images were
confirmed. So we can't do this for compressed images.
In the past, this function just used the passed-in binding number to
index into the array of bindings. When the binding numbers and the
indices of the array matched up, this worked really well.
When they didn't, it broke spectacularly.
So now we keep track of which binding numbers map to which elements in
the array. That way, we don't have to assume that the array indices and
the binding numbers will match up.
