Implementation:Facebookresearch Habitat lab XRInput

Knowledge Sources	Facebookresearch_Habitat_lab
Domains	Embodied_AI, Human_in_the_Loop
Last Updated	2026-02-15 00:00 GMT

Overview

XRInput manages the state of an XR (extended reality) input system, including head-mounted display (HMD) origin tracking and dual controller button, trigger, and thumbstick states.

Description

This module provides two classes for XR input management:

• XRController: Represents the state of a single XR controller. It tracks:
  • Button states: held, down (just pressed), up (just released), and touched.
  • Thumbstick axis values as a two-element list [x, y].
  • Hand trigger and index trigger analog values (0.0 to 1.0).
  • Whether the controller is currently in the user's hand (_is_controller_in_hand).
  • A reset method that clears per-frame events and optionally resets continuous inputs.

• XRInput: Represents the full XR input system with two controllers (left and right), along with HMD origin position and rotation. It provides:
  • controllers property: List of both XRController instances.
  • left_controller and right_controller properties for direct access.
  • origin_position and origin_rotation for HMD tracking data.
  • A reset method that delegates to each controller's reset.

Constants NUM_CONTROLLERS (2), HAND_LEFT (0), and HAND_RIGHT (1) define the controller indices.

Usage

Use XRInput when building VR/XR-enabled HITL applications where users interact with the simulation using VR controllers. The input state is populated externally from the XR runtime and queried each frame by the application logic.

Code Reference

Source Location

• Repository: Facebookresearch_Habitat_lab
• File: habitat-hitl/habitat_hitl/core/xr_input.py
• Lines: 1-117

Signature

NUM_CONTROLLERS: Final[int] = 2
HAND_LEFT: Final[int] = 0
HAND_RIGHT: Final[int] = 1

class XRController:
    def __init__(self):
        ...

    def get_button(self, button) -> bool:
        ...

    def get_button_down(self, button) -> bool:
        ...

    def get_button_up(self, button) -> bool:
        ...

    def get_button_touched(self, button) -> bool:
        ...

    def get_thumbstick(self) -> list[float]:
        ...

    def get_index_trigger(self) -> float:
        ...

    def get_hand_trigger(self) -> float:
        ...

    def get_is_controller_in_hand(self) -> bool:
        ...

    def reset(self, reset_continuous_input: bool = True):
        ...

class XRInput:
    def __init__(self):
        ...

    @property
    def controllers(self) -> list[XRController]:
        ...

    @property
    def left_controller(self) -> XRController:
        ...

    @property
    def right_controller(self) -> XRController:
        ...

    @property
    def origin_position(self) -> list[float]:
        ...

    @property
    def origin_rotation(self) -> list[float]:
        ...

    def reset(self, reset_continuous_input: bool = True):
        ...

Import

from habitat_hitl.core.xr_input import XRInput, XRController, HAND_LEFT, HAND_RIGHT

I/O Contract

Inputs

Name	Type	Required	Description
(none)	-	-	Both XRInput and XRController constructors take no parameters. State is populated externally from the XR runtime.

Outputs

Name	Type	Description
get_button(button)	bool	Whether the specified XRButton is currently held.
get_button_down(button)	bool	Whether the specified XRButton was pressed this frame.
get_button_up(button)	bool	Whether the specified XRButton was released this frame.
get_button_touched(button)	bool	Whether the specified XRButton is currently being touched.
get_thumbstick()	list[float]	Two-element list [x, y] for the thumbstick axis values.
get_index_trigger()	float	Analog value (0.0-1.0) of the index trigger.
get_hand_trigger()	float	Analog value (0.0-1.0) of the hand/grip trigger.
get_is_controller_in_hand()	bool	Whether the controller is currently detected in the user's hand.
origin_position	list[float]	Three-element list [x, y, z] for HMD origin position.
origin_rotation	list[float]	Four-element list [x, y, z, w] for HMD origin rotation (quaternion).

Usage Examples

Basic Usage

from habitat_hitl.core.xr_input import XRInput
from habitat_hitl.core.key_mapping import XRButton

xr_input = XRInput()

# In the frame update loop (state populated by XR runtime):
right = xr_input.right_controller

if right.get_button_down(XRButton.PRIMARY_INDEX_TRIGGER):
    print("Right index trigger pressed!")

trigger_value = right.get_index_trigger()
print(f"Right index trigger analog: {trigger_value:.2f}")

thumbstick = right.get_thumbstick()
print(f"Right thumbstick: x={thumbstick[0]:.2f}, y={thumbstick[1]:.2f}")

# HMD tracking
print(f"HMD origin: {xr_input.origin_position}")

# Reset at end of frame
xr_input.reset()