content: #!/usr/bin/python
  # -*- coding: utf-8 -*-
  import matplotlib
  matplotlib.use('TkAgg')
  
  O.engines=[
  	ForceResetter(),
  	InsertionSortCollider([Bo1_Sphere_Aabb(),Bo1_Box_Aabb()]),
  	InteractionLoop(
  		[Ig2_Sphere_Sphere_ScGeom(),Ig2_Box_Sphere_ScGeom()],
  		[Ip2_FrictMat_FrictMat_FrictPhys()],
  		[Law2_ScGeom_FrictPhys_CundallStrack()]
  	),
  	NewtonIntegrator(damping=0.0,gravity=(0,0,-9.81)),
  	###
  	### NOTE this extra engine:
  	###
  	### You want snapshot to be taken every 1 sec (realTimeLim) or every 50 iterations (iterLim),
  	### whichever comes soones. virtTimeLim attribute is unset, hence virtual time period is not taken into account.
  	PyRunner(iterPeriod=20,command='myAddPlotData()')
  ]
  O.bodies.append(box(center=[0,0,0],extents=[.5,.5,.5],fixed=True,color=[1,0,0]))
  O.bodies.append(sphere([0,0,2],1,color=[0,1,0]))
  O.dt=.002*PWaveTimeStep()
  
  
  ############################################
  ##### now the part pertaining to plots #####
  ############################################
  
  from yade import plot
  ## we will have 2 plots:
  ## 1. t as function of i (joke test function)
  ## 2. i as function of t on left y-axis ('|||' makes the separation) and z_sph, v_sph (as green circles connected with line) and z_sph_half again as function of t
  plot.plots={'i':('t'),'t':('z_sph',None,('v_sph','go-'),'z_sph_half')}
  
  ## this function is called by plotDataCollector
  ## it should add data with the labels that we will plot
  ## if a datum is not specified (but exists), it will be NaN and will not be plotted
  def myAddPlotData():
  	sph=O.bodies[1]
  	## store some numbers under some labels
  	plot.addData(t=O.time,i=O.iter,z_sph=sph.state.pos[2],z_sph_half=.5*sph.state.pos[2],v_sph=sph.state.vel.norm())
  print "Now calling plot.plot() to show the figures. The timestep is artificially low so that you can watch graphs being updated live."
  plot.liveInterval=.2
  plot.plot(subPlots=False)
  O.run(int(5./O.dt));
  #plot.saveGnuplot('/tmp/a')
  ## you can also access the data in plot.data['i'], plot.data['t'] etc, under the labels they were saved.
  