vkd3d: Thoughts on how to include shaders in the project?

[Henri Verbeet]

Hi Philip,

On Mon, 4 Nov 2019 at 19:16, Philip Rebohle
<philip.rebohle at tu-dortmund.de> wrote:
> I'm currently looking into getting Deus Ex: Mankind Divided to run on
> vkd3d. Among other issues, it uses ClearUnorderedAccessView for typed
> buffer views, which is currently not supported and will require the use
> of a compute shader.
>
> There are also a few other areas where shader-based implementations
> might become necessary in the future, e.g. for copies between depth and
> color images, ResolveSubresource with typeless images, etc.
>
> What would be the preferred way to integrate shaders for this purpose in
> vkd3d?
>
I think the preferred way would be to include them as HLSL source, and
use vkd3d-shader to compile them to SPIR-V. The tricky part there is
that the HLSL compiler is currently still a work in progress. It's
possible to use Microsoft's fxc as a replacement—we've used that for
vkmodelviewer in the past—but it seems undesirable to have fxc as a
dependency for vkd3d.

> One option would be to compile GLSL shaders at build-time to a C header
> containing the SPIR-V code, which could then be included in the vkd3d
> source files directly.
>
> This would introduce glslangValidator as a new build-time dependency, is
> that acceptable? Also, how would this be implemented in the build
> system? I don't have much experience with autoconf, so some help in that
> regard would be highly appreciated.
>
In principle, sure. We used to have a dependency on glslangValidator
in the past for the demos, but that was removed in commit
aa5d48eec4987c4c1cb55571b536cd485c25740b once vkd3d-shader became
capable of translating the TPF/DXBC shaders.

> I'd like to avoid including pre-compiled SPIR-V binaries in the source
> tree directly or installing them as separate files if possible, since
> doing so would complicate the workflow significantly.
>
What we typically do (e.g. in the tests) is to include HLSL source in
a comment, and then setup editor commands to generate the equivalent
blob inline. It's not too bad once you have things set up, but it is a
bit of a pain, yes.

Henri