Implementation:Facebookresearch Habitat lab UserMask

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

Overview

UserMask defines the Mask and Users classes that provide bitmask-based user targeting and user set management for the Habitat HITL multi-user framework.

Description

This module provides two core classes for managing multiple users in HITL applications:

• Mask (IntFlag): A bitmask type that represents a set of user indices. It supports standard bitwise operations (|, &, ^, ~) for combining and filtering user sets. Key static methods include:
  • from_index(index): Creates a mask for a single user index.
  • from_indices(indices): Creates a mask for multiple user indices.
  • all_except_index(index): Creates a mask for all users except one.
  • all_except_indices(indices): Creates a mask for all users except a list.
  • Predefined constants: NONE (0), ALL (~0), and MAX_VALUE (32).

• Users: Manages a bounded set of users with activation/deactivation semantics. Users start inactive and can be activated individually. The class provides:
  • indices(user_mask): A generator yielding active user indices that match the given mask.
  • activate_user(user_index) / deactivate_user(user_index): Toggle user activity.
  • to_index_list(user_mask): Convert a mask to a list of active user indices.
  • max_user_count and active_user_count properties.

The bitmask approach allows efficient user targeting in multi-user scenarios, such as sending rendering data or messages to specific subsets of users.

Usage

Use Mask wherever you need to specify which users should receive a message, see a visual element, or be affected by an operation. Use Users to manage the set of active users and iterate over them efficiently.

Code Reference

Source Location

• Repository: Facebookresearch_Habitat_lab
• File: habitat-hitl/habitat_hitl/core/user_mask.py
• Lines: 1-128

Signature

class Mask(IntFlag):
    NONE: Final[int] = 0
    ALL: Final[int] = ~0
    MAX_VALUE: Final[int] = 32

    @staticmethod
    def from_index(index: int) -> Mask:
        ...

    @staticmethod
    def from_indices(indices: List[int]) -> Mask:
        ...

    @staticmethod
    def all_except_index(index: int) -> Mask:
        ...

    @staticmethod
    def all_except_indices(indices: List[int]) -> Mask:
        ...

class Users:
    def __init__(self, max_user_count: int, activate_users: bool = False) -> None:
        ...

    def indices(self, user_mask: Mask) -> Generator[int, Any, None]:
        ...

    def activate_user(self, user_index: int) -> None:
        ...

    def deactivate_user(self, user_index: int) -> None:
        ...

    def to_index_list(self, user_mask: Mask) -> List[int]:
        ...

    @property
    def max_user_count(self) -> int:
        ...

    @property
    def active_user_count(self) -> int:
        ...

Import

from habitat_hitl.core.user_mask import Mask, Users

I/O Contract

Inputs (Users.__init__)

Name	Type	Required	Description
max_user_count	int	Yes	Maximum number of users (0 to 32).
activate_users	bool	No	If True, all users are initially active. Defaults to False.

Outputs

Name	Type	Description
Mask.from_index(i)	Mask	A bitmask with only user index i set.
Mask.from_indices(lst)	Mask	A bitmask with all listed user indices set.
Users.indices(mask)	Generator[int]	Generator yielding active user indices matching the mask.
Users.max_user_count	int	The maximum user count for this Users instance.
Users.active_user_count	int	The number of currently active users.

Usage Examples

Basic Usage

from habitat_hitl.core.user_mask import Mask, Users

# Create a user set with 4 users, all initially active
users = Users(max_user_count=4, activate_users=True)

# Create masks for specific users
user_0_mask = Mask.from_index(0)
users_1_and_2 = Mask.from_indices([1, 2])
all_except_0 = Mask.all_except_index(0)

# Iterate over active users matching a mask
for user_index in users.indices(users_1_and_2):
    print(f"Processing user {user_index}")

# Deactivate a user
users.deactivate_user(2)
print(f"Active users: {users.active_user_count}")

# Combine masks with bitwise operators
combined = user_0_mask | users_1_and_2
for user_index in users.indices(combined):
    print(f"User {user_index} in combined mask")