Only build glslang if Vulkan or Direct3D 12 rendering is enabled

[Calinou]

glslang isn't needed for OpenGL rendering, which includes the web export. This reduces the web release export template's .wasm size by about 20 KB, since web builds use vulkan=no.

This check may need to be revisited once #70315 is merged, as I assume the Direct3D 12 renderer also needs the glslang module to be enabled.

I found this while working on godotengine/godot-docs#8424 🙂

[clayjohn]

Shouldn't this be tied into building for web instead? So it is disabled on web builds and enabled on non-web builds?

[Calinou]

Shouldn't this be tied into building for web instead? So it is disabled on web builds and enabled on non-web builds?

If you build a custom desktop export template with all Vulkan-based renderers disabled, you don't need glslang either as I understand it. (vulkan=no can be used for desktop builds too.)

[akien-mga]

@RandomShaper Do we need glslang for D3D 12?

[RandomShaper]

@RandomShaper Do we need glslang for D3D 12?

We need. For now (including upcoming refactors), glslang is needed for every RenderingDevice backend. In an upcoming PR I'm letting the RD drivers build scripts define RD_ENABLED. That would be the hint to include glslang or not.

Going back to the present, this PR is fine, but will make me add or env['d3d12'] to the script in the D3D12 PR. That's fine as I'll have to rebase anyway and reapply to D3D12 everything happened to Vulkan. However, for future-proofing it, you may want to add it yourself.

[Calinou]

Going back to the present, this PR is fine, but will make me add or env['d3d12'] to the script in the D3D12 PR. That's fine as I'll have to rebase anyway and reapply to D3D12 everything happened to Vulkan. However, for future-proofing it, you may want to add it yourself.

I've done this in this PR, since D3D12 has been merged in master.

[akien-mga]

Thanks!