Interactive Simulation

Interactive simulation is regular task = "simulate" with live inputs enabled. The scenario still owns the model, solver, and output/viewer panels; [sim] chooses the clock policy, [input] maps devices into local state, and [signals.model_inputs] routes that state into Modelica input variables. External browser scenes are just one presentation surface for that same run.

Running the Examples

The interactive examples live under examples/interactive/. They use the same scenario settings surface as batch simulations, but enable input routing and viewer presentation.

Quadrotor SIL

// rumoca-live-scenario: ../repo-examples/interactive/quadrotor/rumoca-scenario.acro.toml

Native run:

cargo xtask repo modelica-deps ensure
cargo run -p rumoca --release -- \
  sim -c examples/interactive/quadrotor/rumoca-scenario.acro.toml

Rover

// rumoca-live-scenario: ../repo-examples/interactive/rover/rumoca-scenario.toml

Native run:

cargo run -p rumoca --release -- \
  sim -c examples/interactive/rover/rumoca-scenario.toml

Fixed-Wing SIL

// rumoca-live-scenario: ../repo-examples/interactive/fixedwing/rumoca-scenario.toml

Native run:

cargo xtask repo modelica-deps ensure
cargo run -p rumoca --release -- \
  sim -c examples/interactive/fixedwing/rumoca-scenario.toml

Reusable Booster Autonomous Landing

// rumoca-live-scenario: ../repo-examples/interactive/reusable_booster/rumoca-scenario.toml

Native run:

cargo xtask repo modelica-deps ensure
cargo run -p rumoca --release -- \
  sim -c examples/interactive/reusable_booster/rumoca-scenario.toml

See Reusable Booster Autonomous Landing for the differential-flatness planner, SE_2(3) controller, gimbal/RCS allocation, and visualization details.

The CLI prints the HTTP and WebSocket endpoints for the viewer. Open the HTTP URL in a browser if it does not open automatically. Use release builds — interactive simulation is real-time work.

Quadrotor Scenario Shape

The quadrotor example is the reference shape:

[rumoca]
version = "1"
task = "simulate"

[model]
file = "QuadrotorSIL.mo"
name = "QuadrotorAcro"

[sim]
dt = 0.01
t_end = 10.0
mode = "realtime"
solver = "rk-like"

[input]
mode = "auto"

Input mappings are scenario-level simulation settings, not viewer settings. The same file then declares local state, keyboard/gamepad bindings, and the bridge into the model:

[locals.throttle]
default = 0.0
type = "float"

[input.gamepad.integrators.throttle]
source = "LeftStickY"
write = "throttle"
deadband = 0.1
rate = 0.7
clamp = [0.0, 1.0]

[input.keyboard.keys.Space]
action = "toggle"
state = "armed"
debounce_ms = 500
precondition = "throttle <= 0.05"

[signals.model_inputs]
stick_throttle = "local:throttle"

[signals.model_inputs.armed]
from = "local:armed"
when_false = 0.0
when_true = 1.0

The external 3D browser view is presentation:

[transport.http]
port = 8080
scene = "quadrotor_scene.js"
asset_dir = "../../assets"

[transport.websocket]
port = 8081

[viewer]
status_title = "Quadrotor"
show_armed = true

Open Settings on the scenario in VS Code, the playground, or the user guide to edit the same TOML through typed controls: input enablement, locals, keys, gamepad axes/buttons/integrators, model-input routes, solver clocking, and viewer panels.

How a Scenario Runs Live

A scenario with only [model] and [sim] is a regular simulation. Live input and live presentation are independent additions:

• [transport.http] + [transport.websocket] — serve the browser viewer (scene = "my_scene.js" selects the 3D scene file). This asks for an external web surface.
• [input], [locals], [signals.model_inputs] — named simulation state and routing from input devices to model input variables. Input alone does not select a special viewer.
• [transport.udp] + [schema]/[receive]/[send] — couple an external process (e.g. a flight controller) over FlatBuffers/UDP.

See Scenario Files for each section.

Pacing

The runtime supports three pacing styles via [sim] mode:

Defaults: lockstep when external coupling is configured, otherwise realtime.

Input Routing

Keyboard, gamepad, and browser inputs go through the generic Rumoca input path. The model side is plain Modelica input variables, so the same model runs in batch (inputs from equations or defaults) and live input runs (inputs from devices) without changing the Modelica source.

Viewer Surfaces

Viewer surfaces are separate from input routing. Standard timeseries/scatter panels use the results viewer. External web scenes use the native realtime scheduled loop and the configured scene script. Both are launched from scenarios, so the same configuration works from the CLI, VS Code, and editor tooling.