[vsg] New port (VulkanSceneGraph)

[cbrl]

• Changes comply with the maintainer guide
• The name of the port matches an existing name for this component on https://repology.org/ if possible, and/or is strongly associated with that component on search engines.
• Optional dependencies are resolved in exactly one way. For example, if the component is built with CMake, all find_package calls are REQUIRED, are satisfied by vcpkg.json's declared dependencies, or disabled with CMAKE_DISABLE_FIND_PACKAGE_Xxx
• The versioning scheme in vcpkg.json matches what upstream says.
• The license declaration in vcpkg.json matches what upstream says.
• The installed as the "copyright" file matches what upstream says.
• The source code of the component installed comes from an authoritative source.
• The generated "usage text" is accurate. See adding-usage for context.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Only one version is in the new port's versions file.
• Only one version is added to each modified port's versions file.

[cbrl]

The pipeline isn't particularly useful since it skips the vulkan dependency. I have tested that the port compiles with the following triplets using VS 2022 for Windows and GCC 11 and GCC 13 for Linux:

• x64-windows
• x64-windows-static
• x64-windows-static-md
• x64-linux
• x64-linux-dynamic

I do not have the ability to test this on ARM or macOS, however.

[FrankXie05]

Related issue: #28529

[FrankXie05]

The usage has been tested successfully locally.

vsg provides CMake targets:

    # this is heuristically generated, and may not be correct
   find_package(vsg CONFIG REQUIRED)
   target_link_libraries(main PRIVATE vsg::vsg)

[dg0yt]

I stumbled over this comment and checked upstream.
https://github.com/vsg-dev/VulkanSceneGraph/blob/f02eba66c8f37e689912363ebd7b9bb79453a8fd/CMakeLists.txt#L40-L63

I think this needs work if you don't want to turn off VSG_SUPPORTS_ShaderCompiler.

• git clone depends on availability of the git tool and bypasses asset caching.
• The clone repo is another fork of what vcpkg offers with port glslang.

[cbrl]

Yeah it's a bit of a problematic aspect of the project. It would be preferable not to disable the shader compiler, but the project vendors its own fork of glslang that might be troublesome to untangle. I will attempt to make it use the vcpkg-provided dependency.

[cbrl]

Seems like it was relatively simple. There were only a few minor changes needed to get vsg to compile with the version of glslang provided by vcpkg. I don't observe any compile issues with the latest commit on any of the triplets I mentioned previously.

[robertosfield]

VulkanSceneGraph project lead here, as a heads up we are experimenting with moving the glslang dependency out from being a insource build to a standard 3rd party dependency. There's a whole tangled web of issue with linking to glslang previously forcing us to resort to the insource build, but slowly it looks like it's distribution is become more standardized so fingers crossed we'll be able to make glslang an external dependency.

I've written up this work on the VSG discussion forum: vsg-dev/VulkanSceneGraph#1199

The work can be found in the external_glslang branch: https://github.com/vsg-dev/VulkanSceneGraph/tree/external_glslang

Once we've seen a bit more cross platform testing I'll merged the external_glslang branch with VSG master and tag a developer release 1.1.5, then eventually we'll get to a 1.2.0 stable release in the next couple of months.