Implementation:Google deepmind Mujoco mj saveLastXML

Knowledge Sources	MuJoCo MuJoCo API Reference
Domains	Model_IO, Serialization
Last Updated	2026-02-15 06:00 GMT

Overview

Concrete tool for exporting the last loaded model as MJCF XML provided by the MuJoCo C API.

Description

The mj_saveLastXML function writes the internally stored XML specification from the last mj_loadXML call to a file or stdout. The output is a canonicalized MJCF XML with all defaults expanded and includes inlined.

Usage

Call after mj_loadXML to export the resolved model. If filename is NULL or empty, output goes to stdout.

Code Reference

Source Location

• Repository: mujoco
• File: src/xml/xml_api.cc
• Lines: 76-96

Signature

int mj_saveLastXML(const char* filename, const mjModel* m,
                   char* error, int error_sz);

Import

#include <mujoco/mujoco.h>

I/O Contract

Inputs

Name	Type	Required	Description
filename	const char*	No	Output file path (NULL/empty for stdout)
m	const mjModel*	Yes	Compiled model (for reference)
error	char*	No	Error buffer
error_sz	int	No	Error buffer size

Outputs

Name	Type	Description
return	int	1 on success, 0 on failure
file	MJCF XML	Written to filename or stdout

Usage Examples

#include <mujoco/mujoco.h>

// Load and re-export as canonical XML
char error[1000];
mjModel* m = mj_loadXML("input.urdf", NULL, error, 1000);
if (m) {
    mj_saveLastXML("output.xml", m, error, 1000);
    mj_deleteModel(m);
}

Related Pages

Implements Principle

• Principle:Google_deepmind_Mujoco_Model_XML_Export