bananakyu100 / usd-rs

usd-rs

Rust bindings for USD.

What works ?

• You can create and open/save/export a stage.
• You can define a prim and get/set attributes on it. All 30 basic types are supported + arrays of those types.
• You can create references under prims or as layers.
• You can traverse the prims in a stage.

Work to do

• Relationships
• Schemas
• Edit Targets
• Variant Sets
• Get/Set default root prim

The parts

• usd-cpp is a crate to build the cpp shared library and its dependencies (tbb, boost ..).
• usd-rs is the actual bindings crate.
• usd-examples will be examples.

Building

• git clone [email protected]:luke-titley/usd-rs.git && cd usd-rs
• git submodule update --init --recursive
• cargo build

Requirements

• g++/clang with c++14 support
• cmake
• python
• and of course cargo

At the moment we use the handy 'build_usd.py' script that is bundled with USD to download all the thirdparty libraries USD depends on. That's why we need python. The USD library uses cmake, and obviously we are going to need a c++ compiler.

Perhaps in the future, it might be possible to port a subset of build_usd.py to our build.rs and so remove the python dependency.

The method

I'm using cpp crate for these bindings in the mid term. This makes it easy to hand write the wrappers and work the api. Work on automatically generated bindings is going on in the background. Ultimately this crate will move over to using usd-sys, when that work is complete.

Adding a new basic type.

The attribute types supported by USD are finite and rarely change. However there are a lot of them, so we employ code generation to implement them. This is handled by the usd-basic-types crate, which is an executable for generating all of the variants. We have to run this manually. All the types are listed in the BASIC_TYPES constant a the top of usd-basic-types/src/main.rs

Add a new type to the constant BASIC_TYPES then run the below command.

cargo run --bin usd-basic-types > usd-rs/src/pxr/vt/basic_types.rs

Why not use macros or build.rs?

We rely on the cpp! macro from rust-cpp, we cannot use this macro inside of another macro.