# 🏋️♀️ bevy_rl
🏗️ Build 🤔 Reinforcement Learning 🏋🏿♂️ [Gym](https://gym.openai.com/) environments with 🕊 [Bevy](https://bevyengine.org/) engine to train 👾 AI agents that 💡 learn from 📺 screen pixels.
## Compatibility
| 0.7 | 0.0.5 |
| 0.8 | 0.8.4 |
| 0.9 | 0.9.0 |
## 📝Features
- Set of APIs to implement OpenAI Gym interface
- REST API to control an agent
- Rendering to RAM membuffer
## 📋 Changelog
- 0.8.4
- Added object representation of observation space
## 👩💻 Usage
### 1. Define App States
```rust
#[derive(Debug, Clone, Eq, PartialEq, Hash)]
enum AppState {
InGame, // where all the game logic is executed
Control, // A paused state in which bevy_rl waits for agent actions
Reset, // A request to reset environment state
}
```
### 2. Define Action Space and Observation Space
A action space is a set of actions that an agent can take. An observation space is a set of observations that an agent can see. Action space can be discrete or continuous. Observations should be serializable to JSON with `serde_json` crate.
```rust
// Action space
bitflags! {
#[derive(Default)]
pub struct PlayerActionFlags: u32 {
const FORWARD = 1 << 0;
const BACKWARD = 1 << 1;
const LEFT = 1 << 2;
const RIGHT = 1 << 3;
}
}
// Observation space
#[derive(Default, Serialize, Clone)]
pub struct EnvironmentState {
pub map: GameMap,
pub actors: Vec<Actor>,
}
```
### 3. Enable AI Gym Plugin
Width and hight should exceed 256, otherwise wgpu will panic.
```rust
let gym_settings = AIGymSettings {
width: 256,
height: 256,
num_agents: 16,
};
app
.insert_resource(gym_settings.clone())
.insert_resource(Arc::new(Mutex::new(AIGymState::<
PlayerActionFlags,
EnvironmentState,
>::new(gym_settings.clone()))))
.add_plugin(AIGymPlugin::<PlayerActionFlags, EnvironmentState>::default())
```
### 4. Implement Environment Logic
`DelayedControlTimer` should pause environment execution to allow agents to take actions.
```rust
struct DelayedControlTimer(Timer);
```
Define systems that implement environment logic.
```rust
app.add_system_set(
SystemSet::on_update(AppState::InGame)
.with_system(turnbased_control_system_switch),
);
app.insert_resource(DelayedControlTimer(Timer::from_seconds(0.1, true))); // 10 Hz
app.add_system_set(
SystemSet::on_update(AppState::Control)
// Game Systems
.with_system(turnbased_text_control_system) // System that parses user command
.with_system(execute_reset_request), // System that performs environment state reset
);
```
`turnbased_control_system_switch` should pause game world and poll `bevy_rl` for agent actions.
```rust
fn turnbased_control_system_switch(
mut app_state: ResMut<State<AppState>>,
time: Res<Time>,
mut timer: ResMut<DelayedControlTimer>,
ai_gym_state: ResMut<Arc<Mutex<AIGymState<PlayerActionFlags>>>>,
) {
if timer.0.tick(time.delta()).just_finished() {
app_state.push(AppState::Control);
physics_time.pause();
let ai_gym_state = ai_gym_state.lock().unwrap();
ai_gym_state.send_step_result(true);
}
}
```
`execute_reset_request` handles environment reset request. `turnbased_control_system_switch` in this example parses agent actions and issues commands to agents in environment via `control_agents`.
```rust
pub(crate) fn execute_reset_request(
mut app_state: ResMut<State<AppState>>,
ai_gym_state: ResMut<Arc<Mutex<AIGymState<PlayerActionFlags>>>>,
) {
let ai_gym_state = ai_gym_state.lock().unwrap();
if !ai_gym_state.is_reset_request() {
return;
}
ai_gym_state.receive_reset_request();
app_state.set(AppState::Reset).unwrap();
}
pub(crate) fn turnbased_control_system_switch(
mut app_state: ResMut<State<AppState>>,
time: Res<Time>,
mut timer: ResMut<DelayedControlTimer>,
ai_gym_state: ResMut<Arc<Mutex<AIGymState<PlayerActionFlags>>>>,
ai_gym_settings: Res<AIGymSettings>,
mut physics_time: ResMut<PhysicsTime>,
) {
if timer.0.tick(time.delta()).just_finished() {
app_state.overwrite_push(AppState::Control).unwrap();
physics_time.pause();
let ai_gym_state = ai_gym_state.lock().unwrap();
let results = (0..ai_gym_settings.num_agents).map(|_| true).collect();
ai_gym_state.send_step_result(results);
}
}
pub(crate) fn turnbased_text_control_system(
agent_movement_q: Query<(&mut heron::prelude::Velocity, &mut Transform, &Actor)>,
collision_events: EventReader<CollisionEvent>,
event_gun_shot: EventWriter<EventGunShot>,
ai_gym_state: ResMut<Arc<Mutex<AIGymState<PlayerActionFlags>>>>,
ai_gym_settings: Res<AIGymSettings>,
mut app_state: ResMut<State<AppState>>,
mut physics_time: ResMut<PhysicsTime>,
) {
let mut ai_gym_state = ai_gym_state.lock().unwrap();
// Drop the system if users hasn't sent request this frame
if !ai_gym_state.is_next_action() {
return;
}
let unparsed_actions = ai_gym_state.receive_action_strings();
let mut actions: Vec<Option<PlayerActionFlags>> =
(0..ai_gym_settings.num_agents).map(|_| None).collect();
for i in 0..unparsed_actions.len() {
let unparsed_action = unparsed_actions[i].clone();
ai_gym_state.set_reward(i, 0.0);
if unparsed_action.is_none() {
actions[i] = None;
continue;
}
let action = match unparsed_action.unwrap().as_str() {
"FORWARD" => Some(PlayerActionFlags::FORWARD),
"BACKWARD" => Some(PlayerActionFlags::BACKWARD),
"LEFT" => Some(PlayerActionFlags::LEFT),
"RIGHT" => Some(PlayerActionFlags::RIGHT),
_ => None,
};
actions[i] = action;
}
// Send environment state to AI Gym
ai_gym_state.set_env_state(EnvironmentState {});
physics_time.resume();
control_agents(actions, agent_movement_q, collision_events, event_gun_shot);
app_state.pop().unwrap();
}
```
## 💻 AIGymState API
| `send_step_result(results: Vec<bool>) ` | Send upon agents interactions are complete |
| `send_reset_result(result: bool) ` | Send when reset request is complete |
| `receive_action_strings(Vec<Option<String>>)` | Recieve environment for agent actions |
| `receive_reset_request()` | Recieve environment for reset request |
| `is_next_action() -> bool` | Whether agent actions are supplied |
| `is_reset_request() -> bool` | Whether reset request was sent |
| `set_reward(agent_index: usize, score: f32)` | Set reward for an agent |
| `set_terminated(agent_index: usize, result: bool)` | Set termination status for an agent |
| `reset()` | Reset bevy_rl state |
| `set_env_state(state: B)` | Set current environment state |
## 🌐 REST API
| Camera Pixels | **GET** | `http://localhost:7878/visual_observations` |
| State | **GET** | `http://localhost:7878/state` |
| Reset Environment | **POST** | `http://localhost:7878/reset` |
| Step | **GET** | `http://localhost:7878/step` `payload=ACTION` |
## ✍️ Examples
[bevy_rl_shooter](https://github.com/stillonearth/bevy_rl_shooter) — example FPS project