While adding geometry stage support for clip/cull, it transpired that the
existing clip/cull support was not setting the type of the result of indexing
into the clup/cull variable. That's a defect independent of the geometry
support, so to simplify the geometry PR, this is addressed separately.
It doesn't appear to change the generated SPIR-V, but that's probably down to
something else tolerating a bad input.
HLSL allows a range of types for clip and cull distances. There are
three dimensions, including arrayness, vectorness, and semantic ID.
SPIR-V requires clip and cull distance be a single array of floats in
all cases.
This code provides input side conversion between the SPIR-V form and
the HLSL form. (Output conversion was added in PR #947 and #997).
This PR extends HlslParseContext::assignClipCullDistance to cope with
the input side conversion. Not as much changed as appears: there was
also a lot of renaming to reflect the fact that the code now handles
either direction.
Currently, non-{frag,vert} stages are not handled, and are explicitly
rejected.
Fixes#1026.
HLSL allows several variables to be declared. There are packing rules involved:
e.g, a float3 and a float1 can be packed into a single array[4], while for a
float3 and another float3, the second one will skip the third array entry to
avoid straddling
This is implements that ability. Because there can be multiple variables involved,
and the final output array will often be a different type altogether (to fuse
the values into a single destination), a new variable is synthesized, unlike the prior
clip/cull support which used the declared variable. The new variable name is
taken from one of the declared ones, so the old tests are unchanged.
Several new tests are added to test various packing scenarios.
Only two semantic IDs are supported: 0, and 1, per HLSL rules. This is
encapsulated in
static const int maxClipCullRegs = 2;
and the algorithm (probably :) ) generalizes to larger values, although there
are a few issues around how HLSL would pack (e.g, would 4 scalars be packed into
a single HLSL float4 out reg? Probably, and this algorithm assumes so).
In HLSL, there are three (TODO: ??) dimensions of clip and cull
distance values:
* The semantic's value N, ala SV_ClipDistanceN.
* The array demension, if the value is an array.
* The vector element, if the value is a vector or array of vectors.
In SPIR-V, clip and cull distance are arrays of scalar floats, always.
This PR currently ignores the semantic N axis, and handles the other
two axes by sequentially copying each vector element of each array member
into sequential floats in the output array.
Fixes: #946
Makes some white-space differences in most output, plus a few cases
where more could have been put out but was cut short by the previous
fix-sized buffer.
