How are arguments passed between the builder and the simulator ?

There is a lot of information expressed in a Builder script that is not directly translatable to a blender model. Here, we describe how the information is passed between a builder script and the simulator.

Properties

Some information is passed directly through the game engine property of each component. This includes things like classpath (which python class implements the logic of this component) or components properties (passed using the morse.builder.abstractcomponent.AbstractComponent.properties() method).

However, passing information through game engine properties has some limitations: it must be one of a limited range of basic types (string, int, double, …), and the range on int and double is limited by Blender. This is insufficient for more complex information.

The component_config.py file

Information concerning scene configuration (i.e. which datastream handler for which component, which service for which component, …) are passed through the file component_config.py stored in the blender scene. You can retrieve it using Blender’s Text Editor window.

This file contains a relatively complex python structure, encoding the configuration for the different parts mentioned above. The file is automatically generated by the Builder using the method morse.builder.abstractcomponent.Configuration.write_config(). On the simulator side, the file is imported in morse.blender.main, and used to create the different internal structures (see The Simulation’s Entry points).

More precisely, the file contains five dictionaries:

• component_datastream contains for each component the list of associated datastream handlers. Each datastream handler is defined by a list of three elements:
  1. the datastream manager
  2. the specific datastream handler class
  3. a dictionary containing extra arguments for the datastream handler
• component_modifier contains for each component the list of associated modifiers. Each modifier is defined by a list of three elements:
  1. its class
  2. the method name in the class
  3. a dictionary containing extra arguments for the modifier class
• component_service contains for each component the list of associated service handlers defined by its classpath.
• overlays contains for each service handler and for each component the list of associated overlays represented by their classpath.
• stream_manager contains for each stream manager a list of options passed to this specific stream manager.

Example

The scene

from morse.builder import *

robot = ATRV()

pose = Pose()
pose.add_stream('socket')
pose.alter('Noise')
robot.append(pose)

odometry = Odometry()
odometry.level("differential")
odometry.add_stream('socket')
robot.append(odometry)

waypoint = Waypoint()
waypoint.add_interface('socket')
robot.append(waypoint)

env = Environment('empty', fastmode=True)
env.configure_stream_manager('socket', time_sync = True, sync_port = 5000)

Generated component_config.py

component_datastream = {'robot.odometry':
    [['morse.middleware.socket_datastream.SocketDatastreamManager',
        'morse.middleware.socket_datastream.SocketPublisher',
        {}]],
'robot.pose':
            [['morse.middleware.socket_datastream.SocketDatastreamManager',
             'morse.middleware.socket_datastream.SocketPublisher',
            {}]],
'robot.waypoint':
            [['morse.middleware.socket_datastream.SocketDatastreamManager',
            'morse.middleware.socket_datastream.SocketReader',
            {}]]}
component_modifier = {'robot.pose': [['morse.modifiers.pose_noise.PoseNoiseModifier', {}]]}
component_service = {'robot.waypoint': ['morse.middleware.socket_request_manager.SocketRequestManager']}
overlays = {}
stream_manager = {'morse.middleware.socket_datastream.SocketDatastreamManager': {'sync_port': 5000,
                                                                                 'time_sync': True}}