# bevy_rl
<img width="209" alt="image" src="https://user-images.githubusercontent.com/97428129/168558015-e6ddd435-dfdf-4f03-b352-070074f5a392.png">
Build [Reinforcement Learning Gym](https://gym.openai.com/) environments
with [Bevy](https://bevyengine.org/) engine to train AI agents that learn from raw screen pixels.
### Compatibility
| 0.7 | 0.0.5 |
| 0.8 | 0.8 |
### Features
- Set of APIs to implement OpenAI Gym interface
- REST API to control an agent
- Rendering to RAM membuffer
### Usage
#### 1. Define Action Space and Application State
```rust
#[derive(Debug, Clone, Eq, PartialEq, Hash)]
enum AppState {
InGame, // Actve state
Control, // A paused state in which application waits for agent input
Reset, // A request to reset environment state
}
// List of possible agent actions (discrete variant)
bitflags! {
#[derive(Default)]
pub struct PlayerActionFlags: u32 {
const IDLE = 1 << 0;
const FORWARD = 1 << 1;
const BACKWARD = 1 << 2;
const LEFT = 1 << 3;
const RIGHT = 1 << 4;
const TURN_LEFT = 1 << 5;
const TURN_RIGHT = 1 << 6;
const SHOOT = 1 << 7;
}
}
```
#### 2. Enable AI Gym Plugin
```rust
let gym_settings = AIGymSettings {
width: 256,
height: 256,
num_agents: 2,
};
app
// bevy_rl initialization
.insert_resource(gym_settings.clone())
.insert_resource(Arc::new(Mutex::new(AIGymState::<PlayerActionFlags>::new(
```
#### 3. Make sure environment is controllable at discreet time steps
```rust
struct DelayedControlTimer(Timer);
```
```rust
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
);
app.add_system_set(
SystemSet::on_update(AppState::InGame)
.with_system(turnbased_control_system_switch),
);
```
```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);
}
}
```
#### 4. Handle Reset & Agent Actions from REST API in Bevy Environment
```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();
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),
"TURN_LEFT" => Some(PlayerActionFlags::TURN_LEFT),
"TURN_RIGHT" => Some(PlayerActionFlags::TURN_RIGHT),
"SHOOT" => Some(PlayerActionFlags::SHOOT),
_ => None,
};
actions[i] = action;
}
physics_time.resume();
control_agents(actions, agent_movement_q, collision_events, event_gun_shot);
app_state.pop().unwrap();
}
```
### REST API
| Camera Pixels | **GET** | `http://localhost:7878/screen.png` |
| Reset Environment | **POST** | `http://localhost:7878/reset` |
| Step | **POST** | `http://localhost:7878/step` `body=ACTION` |