# Copyright 2018 The dm_control Authors.

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

# http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

# ============================================================================

"""The base empty arena that defines global settings for Composer."""

import os

from dm_control import mjcf

from dm_control.composer import entity as entity_module

_ARENA_XML_PATH = os.path.join(os.path.dirname(__file__), 'arena.xml')

class Arena(entity_module.Entity):

"""The base empty arena that defines global settings for Composer."""

def __init__(self, *args, **kwargs):

self._mjcf_root = None # Declare that _mjcf_root exists to allay pytype.

super().__init__(*args, **kwargs)

# _build uses *args and **kwargs rather than named arguments, to get

# around a signature-mismatch error from pytype in derived classes.

def _build(self, *args, **kwargs) -> None:

"""Initializes this arena.

The function takes two arguments through args, kwargs:

name: A string, the name of this arena. If `None`, use the model name

defined in the MJCF file.

xml_path: An optional path to an XML file that will override the default

composer arena MJCF.

Args:

*args: See above.

**kwargs: See above.

"""

if args:

name = args[0]

else:

name = kwargs.get('name', None)

if len(args) > 1:

xml_path = args[1]

else:

xml_path = kwargs.get('xml_path', None)

self._mjcf_root = mjcf.from_path(xml_path or _ARENA_XML_PATH)

if name:

self._mjcf_root.model = name

def add_free_entity(self, entity):

"""Includes an entity in the arena as a free-moving body."""

frame = self.attach(entity)

frame.add('freejoint')

return frame

@property

def mjcf_model(self):

return self._mjcf_root