Use include_bytes! in shader! for automatic recompilation

[mvilim]

This PR makes use of std::include_bytes to automatically recompile path-loaded shaders when they change, as suggested in #890. The resulting variable is left unused, so the compiler is free to optimize it away.

I confirmed that the shader bytes are only included in the binary if debug = true (with debug off and opt-level = 0, the bytes are not present in the final binary). Given the small size of shader files, I assume including their source by default is reasonable. If we would rather not include it by default, I can add a flag to the shader! macro to control the functionality.

I believe this should also close #1231 and #1349.

[Eliah-Lakhin]

@mvilim Merged. Thank you for the improvement!

Regarding #1231 and #1349. Do I understand correctly, it affects glsl source changes detection as well?

[Eliah-Lakhin]

@mvilim From my observations it didn't fully resolve the issue. This is an example of the macro use:

vulkano_shaders::shader! {
    ty: "compute",
    include: [ "./src/shader" ],
    path: "./src/shader/main.glsl",
    types_meta: {
        use serde::{Deserialize, Serialize};

        #[derive(Clone, Copy, PartialEq, Debug, Default, Serialize, Deserialize)]

        impl Eq
    }
}

When I change a file indirectly included in the entry-point(./src/shader/main.glsl) through the shaderc's #include <..> directive, it didn't detect changes. However, if I change the entry-point file itself it does detect the changes.

Perhaps, the more proper solution would be reading such directives and include their sources as well(recursively).

Would you mind working on this additional improvement?

[mvilim]

I didn't even notice the include directive. Thanks for catching that issue. I have opened #1529 with a fix. Thankfully shaderc exposes a mechanism for obtaining the set of files used in the compilation.