Yuval Tassa
5e99ca6cb8
The writer consumes the same generated rows as the reader. mjXWriter::WriteAttrTable drives the mechanical attributes of an element from its mjXAttr rows: each bound field is compared against the class default at the same offset -- the default object is the same struct type, so the rows carry no comparison values -- and attributes equal to their default are skipped. A null default object means the element has no defaults, and every defined value is written. Ranged-arity rows write with trailing-default trimming, which the reader makes round-trip exact by refilling from the same default. Call sites upcast to the private mjs base (the friend declarations permit it; mjCMesh gains the friendship its siblings had); the comparison object is def->X().spec, a freshly-defaulted struct for the sections, or zero-initialized for size, whose spec defaults (-1, auto) are resolved by compilation. Converted: pair, geom, site, joint, camera, light, material, the equality family, both tendon types (the fixed rows are the spatial rows without appearance attributes -- exactly the tag difference), the actuator, flex with its three sub-elements, mesh, skin, option, the six visual sub-sections, statistic and size. The remnants keep names, files, resolved reference strings (the mjC classes null their private base's string pointers; resolved names live behind accessors), and the writing=custom policies the schema declares: compile directives never saved (fromto, springdamper, fitscale), type-dependent lengths and attributes (sizes, joint pos/axis/limited, shellinertia), and alternatives (mass/density, fovy-versus-intrinsics, the plugin-gated gain/bias family). Compiler keeps its write-if-nonzero policy; keyframe keeps its model-sized vectors. Saved files are canonical: attributes follow schema declaration order with remnants trailing, and sections follow the schema's dependency order (statistic before visual, deformable before the contact and equality sections that name flexes, tendon before the equality constraints that name tendons, custom demoted to the data tail). Uniform behavior fixes fall out: default-equal positionals are dropped, dynprm is trimmed like every other ranged vector, and mesh material -- read into the spec but never written -- now survives save/load round trips. Changelog entries ride along. Verified: full suite, doc_test, and the two-tier A/B harness -- saved XML reorders attributes, and every corpus model reloads to a byte-identical binary. PiperOrigin-RevId: 958255003 Change-Id: I5fe7346014450db88b2f3f8680a8f616f7d31266
MuJoCo Python Bindings
This package is the canonical Python bindings for the MuJoCo physics engine. These bindings are developed and maintained by Google DeepMind, and is kept up-to-date with the latest developments in MuJoCo itself.
The mujoco package provides direct access to raw MuJoCo C API functions,
structs, constants, and enumerations. Structs are provided as Python classes,
with Pythonic initialization and deletion semantics.
It is not the aim of this package to provide fully fledged
scene/environment/game authoring API, as there are already a number of existing
packages that do this well. However, this package does provide a number of
lower-level components outside of MuJoCo itself that are likely to be useful to
most users who access MuJoCo through Python. For example, the egl, glfw, and
osmesa subpackages contain utilities for setting up OpenGL rendering contexts.
Installation
The recommended way to install this package is via PyPI:
pip install mujoco
A copy of the MuJoCo library is provided as part of the package and does not need to be downloaded or installed separately.
Source
IMPORTANT: Building from source is only necessary if you are modifying the Python bindings (or are trying to run on exceptionally old Linux systems). If that's not the case, then we recommend installing the prebuilt binaries from PyPI.
If you need to build the Python bindings from source, please consult the documentation.
Usage
Once installed, the package can be imported via import mujoco. Please consult
our documentation for
further detail on the package's API.
We recommend going through the tutorial notebook which covers the basics of
MuJoCo using Python:
Versioning
The major.minor.micro portion of the version number matches the version of
MuJoCo that the bindings provide. Optionally, if we release updates to the
Python bindings themselves that target the same version of MuJoCo, a .postN
suffix is added, for example 2.1.2.post2 represents the second update to the
bindings for MuJoCo 2.1.2.
License and Disclaimer
Copyright 2022 DeepMind Technologies Limited
MuJoCo and its Python bindings are licensed under the Apache License, Version 2.0. You may obtain a copy of the License at https://www.apache.org/licenses/LICENSE-2.0.
This is not an officially supported Google product.