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| """Defines a post-processing function that merges MJCF fixed joints into their parent body.""" | ||
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| import argparse | ||
| import logging | ||
| import xml.etree.ElementTree as ET | ||
| from pathlib import Path | ||
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| logger = logging.getLogger(__name__) | ||
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| def remove_fixed_joints(mjcf_path: str | Path) -> None: | ||
| """Merges fixed joints into their parent body. | ||
| This function works by finding all of the body links which do not have a | ||
| joint element, and converting them from a body element to a site element. | ||
| Args: | ||
| mjcf_path: The path to the MJCF file to process. | ||
| """ | ||
| tree = ET.parse(mjcf_path) | ||
| root = tree.getroot() | ||
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| # Find all body elements | ||
| worldbody = root.find(".//worldbody") | ||
| if worldbody is None: | ||
| return | ||
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| bodies_to_merge = [] | ||
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| # Find all bodies that don't have joints | ||
| for parent_body in worldbody.findall(".//body"): | ||
| if parent_body.find("freejoint") is not None: | ||
| continue | ||
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| for child_body in parent_body.findall("body"): | ||
| if child_body.find("joint") is not None: | ||
| continue | ||
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| bodies_to_merge.append((parent_body, child_body)) | ||
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| for parent_body, child_body in bodies_to_merge: | ||
| parent_name = parent_body.attrib["name"] | ||
| child_name = child_body.attrib["name"] | ||
| logger.info("Merging body %s into %s", child_name, parent_name) | ||
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| # Create a site element at the position of the merged body | ||
| site = ET.SubElement(parent_body, "site") | ||
| site.set("name", child_name) | ||
| for attr in ["pos", "quat", "euler"]: | ||
| if child_body.get(attr): | ||
| site.set(attr, child_body.get(attr)) | ||
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| # Transfer all child elements except inertial to the parent | ||
| for grandchild in child_body: | ||
| if grandchild.tag != "inertial": | ||
| child_body.remove(grandchild) | ||
| parent_body.append(grandchild) | ||
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| # Remove the merged body | ||
| parent_body.remove(child_body) | ||
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| # Save the modified XML | ||
| tree.write(mjcf_path, encoding="utf-8", xml_declaration=True) | ||
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| def main() -> None: | ||
| parser = argparse.ArgumentParser() | ||
| parser.add_argument("mjcf_path", type=Path) | ||
| args = parser.parse_args() | ||
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| remove_fixed_joints(args.mjcf_path) | ||
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| if __name__ == "__main__": | ||
| # python -m urdf2mjcf.postprocess.merge_fixed | ||
| main() |