🚀 API Quick Reference#

📋 Core Module - `motrixsim`#

Function Category	API	Description
Model Loading	`load_model(path)`	Load MJCF/URDF model files
Simulation Step	`step(model, data)`	Execute a single simulation time step
Kinematics	`forward_kinematic(model, data)`	Perform forward kinematics computation

🔧 Core Objects#

Object	Type	Usage Description
`SceneModel`	Model	Static simulation world description, including robot geometry, joints, and sensor definitions
`SceneData`	Data	Dynamic simulation state, storing real-time data such as positions and velocities
`Options`	Config	Simulation parameter settings, controlling integrator and solver parameters

🔍 Named Access - Model Component Access#

MotrixSim provides convenient named access interfaces for model components, supporting direct access and manipulation of various components by name or index.

🔧 Access Methods#

MotrixSim’s Named Access supports two access methods:

Access by name: model.get_body("my_body")
Access by index: model.get_body(0)

Each component access method returns the corresponding component object, providing its properties and methods.

🎯 Model Components#

Component	Access Method	Returned Object Functionality	Index Query Method
Body	`model.get_body(name/id)`	Get rigid body pose, DoF state	`get_body_index(name)`
Link	`model.get_link(name/id)`	Get link pose, velocity	`get_link_index(name)`
Joint	`model.get_joint(name/id)`	Set/get joint position, velocity	`get_joint_index(name)`
Site	`model.get_site(name/id)`	Get site position, orientation	`get_site_index(name)`
Sensor	`model.get_sensor_value(id, data)`	Read sensor data	-
Actuator	`model.get_actuator(name/id)`	Set actuator control, limits	`get_actuator_index(name)`

🔢 Batch Access#

API	Type	Description
`model.get_actuator_ctrls(data)`	ndarray	Get all actuator control values
`model.get_link_poses(data)`	ndarray	Get positions and orientations of all links
`model.bodies`	List[Body]	List of all body objects
`model.links`	List[Link]	List of all link objects
`model.joints`	List[Joint]	List of all joint objects
`model.sites`	List[Site]	List of all site objects

📊 SceneData - State Data#

Property/Method	Type	Description
`data.dof_pos`	ndarray	DoF position array
`data.dof_vel`	ndarray	DoF velocity array
`data.actuator_ctrls`	ndarray	Set/get actuator control values
`data.reset(model)`	-	Reset scene data state
`data.low`	LowData	Low-level data object (contact info, etc.)

🔨 Model Building Module - `motrixsim.msd`#

Function/Method	Description
`msd.from_file(path)`	Load model file for combining and building
`scene.attach(other, ...)`	Attach another model with transform and prefix
`scene.build()`	Build the final `SceneModel` for simulation

🎨 Rendering Module - `motrixsim.render`#

Object/Class	Category	Main Functionality
`RenderApp`	Main Renderer	Model loading, scene synchronization
`RenderGizmos`	Gizmo Drawing	Drawing spheres, cubes, etc.
`RenderUI`	User Interface	Buttons, switches, controls
`Input`	Input Handler	Keyboard, mouse, ray detection