Example: Cargo + WASM + Assets

This example shows a complex use case, using parts of the other examples:

• Build a “main” binary for the host architecture using Cargo.
• Build a WASM plugin targeting wasm32-wasip2 using Cargo.
• Compile shaders using glslc.
• Compress an .tar.gz “asset pack” containing compiled WASM modules, compiled shaders, and PNG images.

Due to the outdatedness rules and depfile integration, every rule accurately captures the actual dependencies of each step. For example, changing a .glsl file included by one of the shaders will only cause the relevant shaders to be rebuilt, and will cause assets.tar.gz to be repackaged, but it will not cause WASM modules to be rebuilt. Similarly, due to the glob patterns, adding a .png file to the project will cause assets.tar.gz to be repackaged, but nothing else will be rebuilt.

Werkfile:

default target = "build"
default cache-dir = "target"

let cargo = which "cargo"
let glslc = which "glslc"
let wasm-tuple = "wasm32-wasip2"

let profile = "debug"
let wasm-profile = "debug"

let cargo-profile = profile | match {
    "debug" => "dev"
    "%" => "%"
}

let cargo-wasm-profile = wasm-profile | match {
    "debug" => "dev"
    "%" => "%"
}

# Rule to build a WASM target with Cargo.
build "target/{wasm-tuple}/{wasm-profile}/%.wasm" {
    # Cargo uses dashes in package names and underscores in build artifacts, so
    # use a regex to replace it.
    let package-name = "{%:s/_/-/}"

    depfile "target/{wasm-tuple}/{wasm-profile}/%.d"
    run "{cargo} build
        --target={wasm-tuple}
        --profile={cargo-wasm-profile}
        -p {package-name}"
}

# Rule to build a SPIR-V shader with glslc.
build "target/%.{frag|vert|comp}.spv" {
    from "%.{0}"
    depfile "target/%.{0}.d"
    run "{glslc} -MD -MF <depfile> -o <out> <in>"
}

let wasm-targets = ["plugin1", "plugin2"]
                   | map "{wasm-tuple}/{wasm-profile}/{}.wasm"

build "target/assets.tar.gz" {
    from [
        wasm-targets,
        glob "assets/**/*.png",
        glob "shaders/**/*.\{frag,vert,comp\}" | map "target/{}.spv"
    ]

    run "tar -zcf <out> <in*>"
}

# Rule to build the main program.
build "target/{profile}/program{EXE_SUFFIX}" {
    depfile "target/{profile}/program.d"
    run "cargo build -p program --profile={cargo-profile}"
}

# Task to build everything.
task build {
    build ["target/{profile}/program{EXE_SUFFIX}", "target/assets.tar.gz"]
}

# Task that just runs `cargo clean`. This deletes `target/`, so also removes
# compiled shaders.
task clean {
    run "{cargo} clean"
}