Implementation:Google deepmind Mujoco MJX Mesh

Knowledge Sources	Google_deepmind_Mujoco MJX Documentation
Domains	Physics_Simulation, JAX, Mesh_Processing
Last Updated	2026-02-15 04:00 GMT

Overview

Mesh processing utilities that convert MuJoCo geom meshes into convex hull representations suitable for JAX-based collision detection.

Description

This module handles the conversion of mesh geometry data into the ConvexMesh and ConvexInfo data structures required by the convex collision routines. It computes face normals, edge normals, and convex hull representations using scipy and trimesh. The box() function converts box geom info into a convex representation, convex() processes arbitrary mesh data from a MuJoCo model, and hfield() / hfield_prism() handle height field decomposition into prism-shaped convex cells for collision. Coplanar face merging is performed to reduce face counts.

Usage

Called during model loading and collision setup. The convex() function is used to precompute ConvexMesh data stored in the model, while box() and hfield_prism() are invoked at collision time to construct convex representations on the fly.

Code Reference

Source Location

• Repository: Google_deepmind_Mujoco
• File: mjx/mujoco/mjx/_src/mesh.py
• Lines: 1-337

Key Functions

def _get_face_norm(vert: np.ndarray, face: np.ndarray) -> np.ndarray
def _get_edge_normals(face: np.ndarray, face_norm: np.ndarray) -> Tuple[np.ndarray, np.ndarray]
def _convex_hull_2d(points: np.ndarray, normal: np.ndarray) -> np.ndarray
def _merge_coplanar(vert, face, face_norm) -> Tuple
def box(info: GeomInfo) -> ConvexInfo
def convex(m: Union[mujoco.MjModel, Model], data_id: int) -> ConvexMesh
def hfield_prism(vert: jax.Array) -> ConvexInfo
def hfield(m: Union[mujoco.MjModel, Model], data_id: int) -> HFieldInfo

Import

from mujoco.mjx._src.mesh import box
from mujoco.mjx._src.mesh import convex
from mujoco.mjx._src.mesh import hfield

I/O Contract

Inputs

Name	Type	Required	Description
m	mjx.Model or mujoco.MjModel	Yes	Model containing mesh vertex and face data
info	GeomInfo	Yes	Geom properties (position, rotation, size) for box conversion
data_id	int	Yes	Mesh or height field data index within the model
vert	jax.Array	Yes	Vertex positions for height field prism construction

Outputs

Name	Type	Description
ConvexInfo	ConvexInfo	Convex geom info including vertices, faces, normals, and edges
ConvexMesh	ConvexMesh	Precomputed convex mesh data for storage in model
HFieldInfo	HFieldInfo	Height field info with grid data and dimensions

Related Pages

• Environment:Google_deepmind_Mujoco_MJX_JAX_Environment