SOFA Storage

Specificity

The SSD project provides a compatible Database with SOFA framework. There are two main advantages with this specialized Database:

• the recording can be launched whether the simulation is driven by the SOFA GUI or by a Python interpreter;

• callbacks can be defined to record automatically Data fields of SOFA components.

Note

The SOFA version of the Database is able to record data at each time step since it inherits from Sofa.Core.Controller. The event corresponding to the end of the time step is therefore caught and triggers access to the recorded Data fields.

Record Data fields

The way to create such a Database is slightly different than in the Core version. In fact, the Database is considered as a SOFA component and must be added to the scene graph. Only the root node of the scene graph should be given, the Database will then create its own child node and add itself to the graph.

Adding callbacks is very simple, since you only have to specify:

• the Table and the Field to use in the Database;

• the absolute path to the SOFA component in the scene graph and the name of th e Data field to record.

Python InterpreterSOFA GUI

import Sofa
from SSD.SOFA import Database

# Create the root node
root = Sofa.Core.Node('root')
root.addObject('RequiredPlugin', pluginName=['SofaOpenglVisual', 'SofaNonUniformFem', 'SofaLoader', 'SofaConstraint',
                                             'SofaImplicitOdeSolver', 'SofaMeshCollision', 'SofaSimpleFem'])

# Create a falling ball
root.addChild('ball')
root.ball.addObject('EulerImplicitSolver')
root.ball.addObject('CGLinearSolver')
root.ball.addObject('MechanicalObject', name='BallMO', template='Rigid3')
root.ball.addObject('UniformMass', totalMass=1.)

# Add a visual model
root.ball.addChild('visual')
root.ball.visual.addObject('MeshObjLoader', name='Loader', filename='mesh/ball.obj')
root.ball.visual.addObject('OglModel', name='BallOGL', src='@Loader')
root.ball.visual.addObject('RigidMapping', input='@..', output='@.')

# Create a new Database
database = Database(root=root, database_name='ball').new(remove_existing=True)
database.create_table(table_name='Ball')
database.add_callback(table_name='Ball', field_name='center',
                      record_object='@ball.BallMO', record_field='position')
database.add_callback(table_name='Ball', field_name='positions',
                      record_object='@ball.visual.BallOGL', record_field='position')

# Init the scene graph and run some step of the simulation
Sofa.Simulation.init(root)
for _ in range(10):
    Sofa.Simulation.animate(root, root.dt.value)

Hint

Only raw data of Data fields can be recorded with such a method. However, you can still use the SDD.Core API of the Database to “manually” insert data. If you write your scene as a Sofa.Core.Controller, you will be able to process these data operation with event handlers (such as onAnimateBeginEvent or onAnimateEndEvent).

Example: /example/SOFA/storage/record.py