This is a proposed API change in 946, which won't make it into this release.
The intent is to allow slightly larger constants to be specified in the updated
vkd3d_shader_parameter1 structure. In particular, this is large enough to pass
4-dimensional integer or float vectors inline, which the proposed clip plane
implementation will use, as well as other Direct3D FFP parameters.
We could also simply add vkd3d_shader_immediate_constant1 as a separate union
member in vkd3d_shader_parameter1, but this API is a bit cleaner and simpler.
As the newly added documentation describes, this reroll serves two purposes:
* to allow shader parameters to be used for any target type (which allows using
parameters for things like Direct3D 8-9 alpha test),
* to allow the union in struct vkd3d_shader_parameter to contain types larger
than 32 bits (by specifying them indirectly through a pointer).
The SPIR-V backend may emit SPIR-V 1.3 if Vulkan 1.1 is available.
Some extensions which provide wave op instructions are available in
SPIR-V 1.0, but these are not sufficient to implement all Shader Model 6
wave op intrinsics. SPIR-V 1.3 has all of the required instructions, but
does not support reading from a quad at a non-constant (but uniform) lane
index, so it may later prove necessary to introduce a Vulkan 1.2
environment.
