Interactive Simulation

Interactive simulation runs a model continuously with live inputs — keyboard, gamepad, browser controls, or an external process — and streams the state to a browser viewer, including 3D scenes. It uses the same rum.toml scenario format as batch simulation; the scenario selects the model, solver, viewer, input routing, and transport ports.

Running the Examples

Quadrotor software-in-the-loop:

cargo run -p rumoca --release -- \
  sim -c examples/interactive/quadrotor/rum.acro.toml

Rover:

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

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.

How a Scenario Becomes Interactive

A scenario with only [model] and [sim] produces a batch HTML report. Adding transports and input/viewer sections launches the interactive runner instead:

[transport.http] + [transport.websocket] — serve the browser viewer (scene = "my_scene.js" selects the 3D scene file).
[locals], [signals] — named runner state and routing from input devices to model input variables.
[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:

Mode	Behavior	Use
`as_fast_as_possible`	No sleeping; drain inputs	Batch-like exploration
`realtime`	Sleep to wall-clock `dt`, zero-order-hold inputs	Human-in-the-loop browser control
`lockstep`	Step only when an external packet arrives	External interfaces that own the timing

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

Input Routing

Keyboard, gamepad, and viewer inputs go through the generic Rumoca input path; the scenario describes which signals drive which model inputs. The model side is plain Modelica input variables, so the same model runs in batch (inputs from equations or defaults) and interactively (inputs from devices) without modification.

Viewer Modes

The built-in results panel is for plots. External web viewers handle 3D scenes and interactive SIL. Both are launched from scenarios, so the same configuration works from the CLI, VS Code, and editor tooling.