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Improve documentation related to mjSpec element deletion.

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PiperOrigin-RevId: 775677830
Change-Id: I02e51b57956b0b6a20c654326b54e001b498dd96
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Yuval Tassa
2025-06-25 07:22:31 -07:00
committed by Copybara-Service
parent d0faa3624e
commit 18d5d5d03f
7 changed files with 26 additions and 15 deletions
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doc/programming/modeledit.rst
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@@ -96,25 +96,37 @@ Elements cannot be created directly; they are returned to the user by the corres
my_geom->type = mjGEOM_BOX; // set geom type
my_geom->size[0] = my_geom->size[1] = my_geom->size[2] = 0.5; // set box size
mjModel* model = mj_compile(spec, NULL); // compile to mjModel
...
mj_deleteModel(model); // free model
mj_deleteSpec(spec); // free spec
The ``NULL`` second argument to :ref:`mjs_addGeom` is the optional default class pointer. When using defaults
procedurally, default classes are passed in explicitly to element constructors. The global defaults of all elements
(used when no default class is passed in) can be inspected in
`user_init.c <https://github.com/google-deepmind/mujoco/blob/main/src/user/user_init.c>`__.
.. _meMemory:
Memory management
^^^^^^^^^^^^^^^^^
As seen in the examples above, model elements are never allocated by the user directly, but rather returned by a
constructor. The library takes ownership of all elements and frees them when the parent :ref:`mjSpec` is deleted using
:ref:`mj_deleteSpec`. The user is only responsible for freeing :ref:`mjSpec` structs.
.. _meAttachment:
Attachment
^^^^^^^^^^
This framework introduces a powerful new feature: attaching and detaching model subtrees. This feature is already used
to power the :ref:`attach<body-attach>` an :ref:`replicate<replicate>` meta-elements in MJCF. Attachment allows the user
to move or copy a subtree from one model into another, while also copying or moving related referenced assets and
referencing elements from outside the kinematic tree (e.g., actuators and sensors). Similarly, detaching a subtree will
remove all associated elements from the model. The default behavior is to move the child into the parent while
attaching, so subsequent changes to the child will also change the parent. Alternatively, the user can choose to make an
entirely new copy during attach using :ref:`mjs_setDeepCopy`. This flag is temporarily set to true while parsing XMLs.
It is possible to :ref:`attach a body to a frame<mjs_attach>`:
This framework introduces a powerful new feature: attaching and deleting model subtrees. This feature is already used to
power the :ref:`attach<body-attach>` an :ref:`replicate<replicate>` meta-elements in MJCF. Attachment allows the user to
move or copy a subtree from one model into another, while also copying or moving related referenced assets and
referencing elements from outside the kinematic tree (e.g., actuators and sensors). Similarly, deleting a subtree will
remove all associated elements from the model. The default behavior ("shallow copy") is to move the child into the
parent while attaching, so subsequent changes to the child will also change the parent. Alternatively, the user can
choose to make an entirely new copy during attach using :ref:`mjs_setDeepCopy`. This flag is temporarily set to true
while parsing XMLs. It is possible to :ref:`attach a body to a frame<mjs_attach>`:
.. code-block:: C