Does SwiftUSD use Rust OpenUSD bindings?

[beeeeep54]

Hi 👋

I stumbled across this project when researching OpenUSD bindings for Rust, and I noticed that this project uses Rust as well. Poking around in the code appeared to show some kind of Rust Swift interop, but I can't find where the actual C++ interop is?

The main thing I'm wondering is, does this project use OpenUSD Rust bindings? And if not, what does it use?

Thanks!

[furby-tm]

Hey there @beeeeep54! This repo does not currently offer any Rust/C++ interop, the code found here is some experimentation with Swift/Rust interop, and that example is only related to one of OpenUSD's dependencies Ptex, that is - this line of Swift, calling directly into (Ptex) C++ code being called from Rust through swift-bridge to convert a Rust u32 unsigned integer to it's equivalent Ptex.MeshType enum value, more as a "simple, dumb, test".

If you're interested in OpenUSD Rust bindings you can find that here, @scott-wilson is the best resource for more information on that, and you can find him on the ASWF slack rust channel.

If you're interested in how interoperability is working between Swift and OpenUSD's C++ codebase, here is how Swift/C++ interop works.

Steps to do this easily...

1. Create a new swift package by running the following in your terminal.

mkdir MyApp
cd MyApp

swift package init

2. Create a new directory, say MyCxx inside the MyApp/Sources directory with the following structure.

Sources/
  MyCxx/
    include/
      MyCxx.h
    MyCxx.cpp

3. Inside the Package.swift file at the project's root, copy the following:

// swift-tools-version: 5.10
import PackageDescription

let package = Package(
  name: "MyApp",
  platforms: [
    .macOS(.v14),
    .visionOS(.v1),
    .iOS(.v17),
    .tvOS(.v17),
    .watchOS(.v10)
  ],
  targets: [
    .target(
      name: "MyCxx"
    ),

    .executableTarget(
      name: "MyApp",
      dependencies: [
        .target(name: "MyCxx")
      ],
      swiftSettings: [
        // enable c++ interop.
        .interoperabilityMode(.Cxx)
      ]
    )
  ],
  // set c++ language standard.
  cxxLanguageStandard: .cxx17
)

4. Inside MyApp/Sources/MyCxx add some simple c++ code to test with.

// MyCxx.h
#pragma once

void doSomething();

// MyCxx.cpp
#include "MyCxx.h"

#include <stdio.h>

void doSomething()
{
  printf("Hello from C++!\n");
}

5. Inside MyApp/Sources/MyApp/MyApp.swift add the following to interop with your c++ library directly in swift.

import MyCxx

@main
struct MyApp {
  static func main() {
    doSomething() // should print "Hello from C++!"
  }
}

6. Back in your terminal, build and run your Swift/C++ app.

swift run
# "Hello from C++!"

Hopefully that helps! Cheers 👋🏻.

[beeeeep54]

Thanks so much for the help!

[furby-tm]

Anytime! Feel free to reach out about anything else 👍🏻.