DART Python Bindings (dartpy)

Load this skill when working with Python bindings or dartpy.

When a binding exposes or changes model/scene loading, dynamics, collision/contact/constraints, simulation stepping, GUI/Filament output, or a visual example, also load dart-verify-sim. Pair a focused Python text/behavior oracle with an assessed, claim-tied Filament capture; document a visual exception when capture is unavailable or not applicable.

Quick Start

import dartpy as dart

world = dart.simulation.World()
loader = dart.utils.DartLoader()
skel = loader.parseSkeleton("dart://sample/urdf/six_axis_arm/six_axis_arm.urdf")
world.addSkeleton(skel)

for _ in range(100):
    world.step()

Full Documentation

For complete Python bindings guide: docs/onboarding/python-bindings.md

For current examples and test patterns: python/examples/ and python/tests/

Quick Commands

pixi run build-py-dev    # Build for development
pixi run test-py         # Run Python tests that need no graphics device
pixi run test-gui        # Run dartpy.gui rendering and integration tests

Wheel Building

This development branch ships Pixi-managed wheel tasks. The core tasks are wheel-build-core, wheel-repair-linux-core, wheel-repair-macos-core, wheel-repair-windows-core, wheel-verify-core, and wheel-test-core; the py312-wheel environment exposes wheel-build, wheel-repair, wheel-verify, and wheel-test on top of them, and py313-wheel exposes wheel-test-abi3. Every wheel is cp312-abi3, built by scikit-build-core from pyproject.toml. CI runs them in .github/workflows/publish_dartpy.yml (for example pixi run -e py312-wheel wheel-build). See docs/onboarding/python-bindings.md for the wheel workflow overview.

Key Patterns

• nanobind is dartpy's only binder on main, under python/dartpy/. Use the DART 6.20 compatibility notes in the owner guide.
• Until the PLAN-624 rename lands, follow the current binding names in python/examples and python/tests; bind new DART 7 APIs directly in the DART 7 Python style (snake_case, properties, keyword-only options) from the PLAN-624 design doc.
• NumPy arrays auto-convert to Eigen types
• dartpy.gui always exists: dartpy requires DART_BUILD_IO and DART_BUILD_GUI. GUI callers use the Filament-backed dart.gui.Viewer and related neutral classes; import and viewer construction need no display.

Key Files

• Package config: pyproject.toml (scikit-build-core) and the PEP 517 wrapper scripts/pep517/dartpy_backend.py
• Package files: python/dartpy/package/ (__init__.py, py.typed, experimental/)
• Binding dependencies: python/CMakeLists.txt
• Binding build system: python/dartpy/CMakeLists.txt