Implementation:Google deepmind Mujoco User Init

Knowledge Sources	Google_deepmind_Mujoco
Domains	Physics Simulation, Default Initialization
Last Updated	2026-02-15 04:00 GMT

Overview

Provides default initialization functions for all MuJoCo specification data structures in pure C.

Description

user_init.c defines default initializers for all major MuJoCo specification types including mjs_defaultSpec, mjs_defaultBody, mjs_defaultOrientation, and many others. It uses memset to zero-initialize structures, then sets specific defaults such as compiler settings (autolimits, euler sequence, threading), engine options (via mj_defaultOption and mj_defaultVisual), and per-element defaults like quaternion identity values. Being a C file, it serves as the foundation for ensuring all spec structures start in a well-defined state.

Usage

Called internally whenever a new specification element is created, ensuring all fields have sensible default values before user modifications.

Code Reference

Source Location

• Repository: Google_deepmind_Mujoco
• File: src/user/user_init.c
• Lines: 1-386

Key Functions

void mjs_defaultSpec(mjSpec* spec);
void mjs_defaultOrientation(mjsOrientation* orient);
void mjs_defaultBody(mjsBody* body);

Import

#include "user/user_api.h"
#include <mujoco/mjspec.h>

I/O Contract

Inputs

Name	Type	Required	Description
spec	mjSpec*	Yes	Specification structure to initialize with defaults
body	mjsBody*	Yes	Body structure to initialize with defaults
orient	mjsOrientation*	Yes	Orientation structure to initialize with defaults

Outputs

Name	Type	Description
void	void	Structures are modified in-place with default values

Related Pages

• Environment:Google_deepmind_Mujoco_C_Build_Environment