fix: support multiple worldbody elements in MJCF parser#1496
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adenzler-nvidia merged 1 commit intoJan 29, 2026
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MuJoCo allows multiple <worldbody> elements in a single model (e.g.,
when using <include> to bring in separate MJCF files). Previously,
Newton's parser only processed the first worldbody element.
Changed root.find('worldbody') to iterate over root.findall('worldbody')
so all worldbody elements are processed into the world body, matching
MuJoCo's behavior.
Added tests for:
- Multiple inline worldbody elements with geoms and bodies
- Multiple worldbody elements with sites
- Includes that create multiple worldbody elements
Contributor
📝 WalkthroughWalkthroughModified MJCF parsing to support multiple worldbody elements instead of a single worldbody. Restructured parsing logic to loop through each worldbody and process its child elements (bodies, geoms, sites, frames) within per-world context. Added comprehensive test coverage for multiple worldbody scenarios. Changes
Estimated code review effort🎯 3 (Moderate) | ⏱️ ~20 minutes Possibly related PRs
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Actionable comments posted: 1
🤖 Fix all issues with AI agents
In `@newton/tests/test_import_mjcf.py`:
- Around line 4183-4187: The xml_resolver function currently has an unused
parameter base_dir causing ARG001; rename that parameter to _base_dir (or prefix
with an underscore) in the xml_resolver definition so the signature reads
xml_resolver(_base_dir, file_path) (or explicitly ignore it) and update any
references accordingly to silence Ruff while keeping behavior intact for the
xml_resolver function used in the tests.
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MuJoCo allows multiple elements in a single model (e.g., when using to bring in separate MJCF files). Previously, Newton's parser only processed the first worldbody element.
Changed root.find('worldbody') to iterate over root.findall('worldbody') so all worldbody elements are processed into the world body, matching MuJoCo's behavior.
Added tests for:
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newton/tests/test_examples.py)pre-commit run -aSummary by CodeRabbit
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