av3-animation-as-crab/README.md

Animator As Crab

A hard fork of Animator As Code where animator controllers are written in Rhai instead of C#.

A Rhai script is evaluated by a Rust library (libaac), which validates it and emits the whole controller as JSON. A Unity Editor window deserializes that JSON and builds a real AnimatorController through the original Animator As Code V1 library, which is left untouched.

script.rhai --> libaac (Rust) --JSON--> AacCrabWindow (Unity Editor) --> AnimatorController

Layout

Path	Contents
rust/	The Rhai DSL, graph model, validator, and the libaac cdylib.
rust/examples/avatar.rhai	The reference script, exercising every feature of the DSL.
csharp/dev.doloro.animator-as-crab/	The Unity package: the untouched Animator As Code V1 library and the bridge in V1/Editor/Crab/.
flake.nix	Dev shell with the Rust toolchain, dotnet, mono, and jq.

Building

nix develop
cargo test --manifest-path rust/Cargo.toml
cargo run --bin aac-dump -- rust/examples/avatar.rhai    # print the generated JSON
nix build .#aac                                          # libaac.so + aac-dump

Copy libaac.so (or libaac.dll, libaac.dylib) into the Unity project's Assets/Plugins folder, and add csharp/dev.doloro.animator-as-crab to the project's packages.

Writing a script

let aac = AnimatorAsCode();
aac.system_name("MyAvatar");
aac.asset_key("AAC_");

let speed = aac.float_param("Speed", 0.0);
let ctrl = aac.new_controller();
let base = ctrl.layer("Base");

let idle = base.state("Idle", 0, 0);
let walk = base.state("Walk", 1, 0);

let walk_clip = aac.clip("walk_anim");
walk_clip.toggle("Body/Props", true);

walk.set_clip(walk_clip);
idle.transition_to(walk).when(speed > 0.1).no_exit_time().duration(0.25);

Conditions are written on the parameters themselves (speed > 0.1, is_sitting == true). There is no && or || — Rhai's are short-circuit built-ins that cannot be overloaded — so use when_all([speed < 0.05, is_sitting == false]).

See rust/examples/avatar.rhai for the full surface: parameters, clips, curves, blend trees, sub-state machines, any-state transitions, and transition settings.

Generating

Open Tools > Animator As Crab and fill in the window:

• the path to the .rhai script (it is watched, so saving the script regenerates the controller),
• the AnimatorController to generate into,
• the animator root, the asset container, and the container mode,
• whether states should write defaults.

Nothing is defaulted silently, and the controller is rebuilt with Animator As Code's modification API: the controller is cleared, and the clips and blend trees of the same asset key are removed from the container before being recreated. Animator As Code's own C# API is untouched and still usable on the same controller.

Limitations

• The Unity side has not been run: there is no Unity project in this repository, so the bridge and the generator are verified by reading, not by executing.
• Blend trees can only nest a blend tree that was declared earlier in the script.
• The graph carries no avatar masks, layer weights, state behaviours, or parameter drivers yet.