Currently the mutable descriptor set is repeated many times in the
pipeline layout in order to cover the indices for all the
descriptor types that would be present if mutable descriptors were
not used. This is useless and wasteful, but was necessary before
the descriptor sets backing the SRV-UAV-CBV heap were moved at the
end of the allocation table because descriptor set indices are
currently a compile-time constant in many places.
Now this is not needed any more and we can just avoid putting
many copies of the mutable descriptor set in the pipeline layout,
making it easier to meet Vulkan implementation limits.
So that when mutable descriptors are in use we can avoid putting
the other descriptor sets backing the SRV-UAV-CBV descriptor heap
in the pipeline layout altogether.
So we avoid hardcoding that it is number zero. There are two
goals here: first making the code easier to understand and
second allow reshuffling the descriptor set allocation in a
later commit.
The descriptor heap implementation is a rather central behavior element
in vkd3d, so it's useful to have all the relevant information logged
in a single place.
Slightly simplifies descriptor write addressing, and makes layouts
essentially the same as array layouts, differing only in the binding
details, and therefore easier to understand. This also simplifies the
addition of storage buffer bindings, which can all be added onto the end.
Allows descriptor set layouts to be created after all bindings are
mapped. This is less complex and fragile than the current scheme, and in
a future patch it will support separating descriptor types into different
sets. Descriptors on virtual heaps are currently allocated from pools
which contain an equal number of each descriptor type used by vkd3d, and
this can waste a significant amount of device memory.
Enables the bounded range to be mapped to the unbounded one, instead of
being mapped to a separate binding which will be populated from the same
d3d12 descriptors as the unbounded one.
Based on the design document, "The runtime will not clamp or validate
the input, but implementations may clamp to the range [0,1] if necessary.",
so we test for the EXT_depth_range_unrestricted extension, and only clamp if
it's not available (thus, necessary to do so).
NaNs are converted to zero as per "NaNs must be treated as 0, but the runtime
will convert NaNs to 0 on behalf of the implementation.", and a default bounds
are set to 0.0 and 1.0.
The existing code sets "stageFlags" to VK_SHADER_STAGE_ALL when
"use_vk_heaps" is true, but doesn't adjust the visibility. This
potentially violates the "Any two elements of pPushConstantRanges must
not include the same stage in stageFlags" constraint, and causes the
validation layers to complain accordingly.
vkd3d might decide to disable some extensions after the chain is created,
so the chain must be recreated with only the structures corresponding to
enabled extensions.
Similarly to a54187f3c9c9ad4a5d1357721104f28c498ac112, this fixes some validation
errors on devices that do not support tessellation; the Adreno 540 on my OnePlus 5
phone in my specific case.
