# encoding: utf-8

# script for periodic simple shear test, with periodic boundary
# first compresses to attain some isotropic stress (checkStress),
# then loads in shear (checkDistorsion)
#
# the initial packing is either regular (hexagonal), with empty bands along the boundary,
# or periodic random cloud of spheres
#
# material friction angle is initially set to zero, so that the resulting packing is dense
# (sphere rearrangement is easier if there is no friction)
#

# setup the periodic boundary
O.periodic = True
O.cell.hSize = Matrix3(2, 0, 0, 0, 2, 0, 0, 0, 2)

from yade import pack, plot

# the "if 0:" block will be never executed, therefore the "else:" block will be
# to use cloud instead of regular packing, change to "if 1:" or something similar
if 0:
	# create cloud of spheres and insert them into the simulation
	# we give corners, mean radius, radius variation
	sp = pack.SpherePack()
	sp.makeCloud((0, 0, 0), (2, 2, 2), rMean=.1, rRelFuzz=.6, periodic=True)
	# insert the packing into the simulation
	sp.toSimulation(color=(0, 0, 1))  # pure blue
else:
	# in this case, add dense packing
	O.bodies.append(pack.regularHexa(pack.inAlignedBox((0, 0, 0), (2, 2, 2)), radius=.1, gap=0, color=(0, 0, 1)))

# create "dense" packing by setting friction to zero initially
O.materials[0].frictionAngle = 0

# simulation loop (will be run at every step)
O.engines = [
        ForceResetter(),
        InsertionSortCollider([Bo1_Sphere_Aabb()]),
        InteractionLoop(
                # interaction loop
                [Ig2_Sphere_Sphere_ScGeom()],
                [Ip2_FrictMat_FrictMat_FrictPhys()],
                [Law2_ScGeom_FrictPhys_CundallStrack()]
        ),
        NewtonIntegrator(damping=.4),
        # run checkStress function (defined below) every second
        # the label is arbitrary, and is used later to refer to this engine
        PyRunner(command='checkStress()', realPeriod=1, label='checker'),
        # record data for plotting every 100 steps; addData function is defined below
        PyRunner(command='addData()', iterPeriod=100)
]

# set the integration timestep to be 1/2 of the "critical" timestep
O.dt = .5 * PWaveTimeStep()

# prescribe isotropic normal deformation (constant strain rate)
# of the periodic cell
O.cell.velGrad = Matrix3(-.1, 0, 0, 0, -.1, 0, 0, 0, -.1)

# when to stop the isotropic compression (used inside checkStress)
limitMeanStress = -5e5


# called every second by the PyRunner engine
def checkStress():
	# stress tensor as the sum of normal and shear contributions
	# Matrix3.Zero is the intial value for sum(...)
	stress = getStress().trace() / 3.
	print('mean stress', stress)
	# if mean stress is below (bigger in absolute value) limitMeanStress, start shearing
	if stress < limitMeanStress:
		# apply constant-rate distorsion on the periodic cell
		O.cell.velGrad = Matrix3(0, 0, .1, 0, 0, 0, 0, 0, 0)
		# change the function called by the checker engine
		# (checkStress will not be called anymore)
		checker.command = 'checkDistorsion()'
		# block rotations of particles to increase tanPhi, if desired
		# disabled by default
		if 0:
			for b in O.bodies:
				# block X,Y,Z rotations, translations are free
				b.state.blockedDOFs = 'XYZ'
				# stop rotations if any, as blockedDOFs block accelerations really
				b.state.angVel = (0, 0, 0)
		# set friction angle back to non-zero value
		# tangensOfFrictionAngle is computed by the Ip2_* functor from material
		# for future contacts change material (there is only one material for all particles)
		O.materials[0].frictionAngle = .5  # radians
		# for existing contacts, set contact friction directly
		for i in O.interactions:
			i.phys.tangensOfFrictionAngle = tan(.5)


# called from the 'checker' engine periodically, during the shear phase
def checkDistorsion():
	# if the distorsion value is >.3, exit; otherwise do nothing
	if abs(O.cell.trsf[0, 2]) > .5:
		# save data from addData(...) before exiting into file
		# use O.tags['id'] to distinguish individual runs of the same simulation
		plot.saveDataTxt(O.tags['id'] + '.txt')
		# exit the program
		#import sys
		#sys.exit(0) # no error (0)
		O.pause()


# called periodically to store data history
def addData():
	# get the stress tensor (as 3x3 matrix)
	stress = sum(normalShearStressTensors(), Matrix3.Zero)
	# give names to values we are interested in and save them
	plot.addData(exz=O.cell.trsf[0, 2], szz=stress[2, 2], sxz=stress[0, 2], tanPhi=(stress[0, 2] / stress[2, 2]) if stress[2, 2] != 0 else 0, i=O.iter)
	# color particles based on rotation amount
	for b in O.bodies:
		# rot() gives rotation vector between reference and current position
		b.shape.color = scalarOnColorScale(b.state.rot().norm(), 0, pi / 2.)


# define what to plot (3 plots in total)
## exz(i), [left y axis, separate by None:] szz(i), sxz(i)
## szz(exz), sxz(exz)
## tanPhi(i)
# note the space in 'i ' so that it does not overwrite the 'i' entry
plot.plots = {'i': ('exz', None, 'szz', 'sxz'), 'exz': ('szz', 'sxz'), 'i ': ('tanPhi',)}

# better show rotation of particles
Gl1_Sphere.stripes = True

# open the plot on the screen
plot.plot()

O.saveTmp()
