import simbios.simtk as simtk

# Create the system.
system = simtk.MultibodySystem()
matter = simtk.SimbodyMatterSubsystem(system)
forces = simtk.GeneralForceSubsystem(system)
gravity = simtk.Force.UniformGravity(forces, matter, (0, -9.8, 0))
pendulumBody = simtk.Body.Rigid(simtk.MassProperties(1.0, (0,0,0), simtk.Inertia(1)))
pendulumBody.addDecoration(simtk.Transform(), simtk.DecorativeSphere(0.1))
pendulum1 = simtk.MobilizedBody.Pin(matter.ground, 
                                   simtk.Transform((0,0,0)), 
                                   pendulumBody, 
                                   simtk.Transform((0, 1, 0)))
system.defaultSubsystem.addEventReporter(simtk.VTKEventReporter(system, 0.01))

# Initialize the system and state.
system.realizeTopology()
state = system.defaultState
pendulum1.setOneU(state, 0, 2.0)

# Simulate it.
integ = simtk.VerletIntegrator(system)
ts = simtk.TimeStepper(system, integ)
ts.initialize(state)
ts.stepTo(5.0)