Implementation:Google deepmind Mujoco MJWarp Util Misc

Knowledge Sources	Google_deepmind_Mujoco MJWarp Documentation
Domains	Physics_Simulation, GPU_Computing, NVIDIA_Warp
Last Updated	2026-02-15 04:00 GMT

Overview

MJWarp Util Misc provides miscellaneous utility functions including Halton sequences, tendon wrapping geometry, muscle dynamics, and point-in-geom testing.

Description

This module collects miscellaneous GPU-compatible utility functions used by various MJWarp subsystems. It includes the Halton quasi-random sequence generator (used for SDF sampling), 2D line segment intersection testing, circle arc length computation, tendon wrapping around cylinders and spheres (wrap, wrap_circle, wrap_inside), muscle gain/bias/dynamics functions for musculotendon actuators, a sigmoid function for smooth muscle activation dynamics, and a point-in-geometry test (inside_geom) for all standard geometry types.

Usage

Called by multiple subsystems: the Halton function is used in SDF collision sampling and benchmarking, wrapping functions are used by the tendon system, muscle functions support musculotendon actuator computation, and inside_geom is used by sensor evaluation.

Code Reference

Source Location

• Repository: Google_deepmind_Mujoco
• File: mjx/mujoco/mjx/third_party/mujoco_warp/_src/util_misc.py
• Lines: 1-632

Key Functions

# Quasi-random sampling
def halton(index: int, base: int) -> float

# 2D geometry
def is_intersect(p1, p2, p3, p4) -> bool

# Tendon wrapping
def length_circle(p0, p1, ind, radius) -> float
def wrap_circle(end, side, radius) -> Tuple[float, wp.vec2, wp.vec2]
def wrap_inside(...)
def wrap(...)

# Muscle model
def muscle_gain_length(length, lmin, lmax) -> float
def muscle_gain(len, vel, lengthrange, acc0, prm) -> float
def muscle_bias(len, lengthrange, acc0, prm) -> float
def muscle_dynamics(control, activation, prm) -> float
def muscle_dynamics_timescale(dctrl, tau_act, tau_deact, smooth_width) -> float

# Point-in-geometry test
def inside_geom(pos, mat, size, geomtype, point) -> bool

Import

from mujoco.mjx.third_party.mujoco_warp._src.util_misc import halton
from mujoco.mjx.third_party.mujoco_warp._src.util_misc import wrap
from mujoco.mjx.third_party.mujoco_warp._src.util_misc import muscle_gain
from mujoco.mjx.third_party.mujoco_warp._src.util_misc import inside_geom

I/O Contract

Inputs

Name	Type	Required	Description
index	int	No	Sequence index for Halton generator
base	int	No	Base for Halton sequence (prime number)
pos	wp.vec3	No	Geometry position for inside_geom test
mat	wp.mat33	No	Geometry rotation for inside_geom test
size	wp.vec3	No	Geometry size for inside_geom test
geomtype	int	No	Geometry type for inside_geom test
point	wp.vec3	No	Query point for inside_geom test

Outputs

Name	Type	Description
result	float/bool	Halton value, muscle force, or containment boolean

Related Pages

• Environment:Google_deepmind_Mujoco_MJX_Warp_CUDA_Environment