Sphere losing interaction with PFacet after moving it to other scene

Asked by Léo Sénique on 2019-08-06

Hello,
I've been trying to use two scenes to handle different stages of my simulation. When one of these stage is over, I copy the spheres from one scene to add them to the other scene. The problem I'm running into is that, despite using the same engines, the spheres interact normally with walls (made of PFacets) in their original scene , but when I delete them and add them to the other scene, they just go through the walls without interacting with them.
Here is an example script using a single sphere and two scenes:

#Import Libraries
from yade.gridpfacet import *
from yade import pack,plot
import math
import random as rand
import numpy as np

# Time step
O.dt=1e-5
Factor=10
RNode=0.01
color=[0.,1.,1.]
gravityVector = Vector3(0.,-9.81,0.)

#Creation of the materials used in the simulation
O.materials.append(FrictMat(density=2500,frictionAngle=math.radians(35.),poisson=0.2,young=1e7,label='Frict')) #Material for the debris flow
O.materials.append(FrictMat(density=2500,frictionAngle=math.radians(70.),poisson=0.2,young=1e7,label='FrictBase'))
O.materials.append( CohFrictMat( young=6e8,poisson=0.3,density=2650,frictionAngle=radians(70.),normalCohesion=3e100,shearCohesion=3e100,momentRotationLaw=True,label='gridNodeMat' ) ) # material to create the gridConnections

engines=[
    ForceResetter(),
 InsertionSortCollider(
 [
  Bo1_Sphere_Aabb(aabbEnlargeFactor=Factor, label="aabb"),
  Bo1_GridConnection_Aabb(),
  Bo1_PFacet_Aabb(),
  Bo1_Facet_Aabb(),
 ],
 verletDist=-0.1,
 allowBiggerThanPeriod=False),
 InteractionLoop(
 #Geometry functors
 [
  Ig2_Sphere_Sphere_ScGeom(),
  Ig2_GridNode_GridNode_GridNodeGeom6D(), #Gridnode-Gridnode
  Ig2_GridConnection_GridConnection_GridCoGridCoGeom(), #Gridconnec-Gridconnec
  Ig2_Sphere_GridConnection_ScGridCoGeom(), #Gridconnec-GridNode
  Ig2_GridConnection_PFacet_ScGeom(), #Gridconnec-Pfacet
  Ig2_Sphere_PFacet_ScGridCoGeom(), #Sphere-Pfacet => required for Gridnode Pfacet
  Ig2_Sphere_Sphere_ScGeom6D(interactionDetectionFactor=Factor,label="Ig2"),
  Ig2_PFacet_PFacet_ScGeom()

    ],
 #Physic functors
 [
  Ip2_FrictMat_FrictMat_LubricationPhys(eta=2,eps=0.01),
        Ip2_CohFrictMat_CohFrictMat_CohFrictPhys()
 ],
 #Law functors
 [
  Law2_ScGeom6D_CohFrictPhys_CohesionMoment(),
  Law2_ScGeom_FrictPhys_CundallStrack(),
  Law2_ScGridCoGeom_FrictPhys_CundallStrack(),
  Law2_ScGeom_WirePhys_WirePM(label='Law_1'), #linkThresholdIteration=1,
  Law2_GridCoGridCoGeom_FrictPhys_CundallStrack(),
  Law2_ScGeom_ImplicitLubricationPhys()
 ]
    ),
    NewtonIntegrator(gravity=gravityVector),
    PyRunner(command='moveSphereToScene()',iterPeriod=500,label='moveSphere',dead=False)
    ]

def addWall():
    nodes=[]
    wall=[]
    nodes.append(O.bodies.append( gridNode([-3.,-3.,-3.],RNode,wire=False,fixed=True,material='gridNodeMat',color=color) ))
    nodes.append(O.bodies.append( gridNode([3.,-3.,-3.],RNode,wire=False,fixed=True,material='gridNodeMat',color=color) ))
    nodes.append(O.bodies.append( gridNode([-3.,-3.,3.],RNode,wire=False,fixed=True,material='gridNodeMat',color=color) ))
    nodes.append(O.bodies.append( gridNode([3.,-3.,3.],RNode,wire=False,fixed=True,material='gridNodeMat',color=color) ))
    for i in nodes:
        for j in nodes:
            if j<i:
                O.bodies.append(gridConnection(i,j,RNode,color=color,material='gridNodeMat'))

    wall.append(O.bodies.append(pfacet(nodes[0],nodes[1],nodes[2],wire=True,material='FrictBase',color=color)))
    wall.append(O.bodies.append(pfacet(nodes[1],nodes[2],nodes[3],wire=True,material='FrictBase',color=color)))

O.engines=engines
addWall()
O.addScene()
O.switchToScene(1)
O.engines=engines
O.dt=1e-5
O.materials.append(FrictMat(density=2500,frictionAngle=math.radians(35.),poisson=0.2,young=1e7,label='Frict')) #Material for the debris flow
O.materials.append(FrictMat(density=2500,frictionAngle=math.radians(70.),poisson=0.2,young=1e7,label='FrictBase'))
O.materials.append( CohFrictMat( young=6e8,poisson=0.3,density=2650,frictionAngle=radians(70.),normalCohesion=3e100,shearCohesion=3e100,momentRotationLaw=True,label='gridNodeMat' ) ) # material to create the gridConnections
addWall()
s1=O.bodies.append(sphere(center=(0,0,0),radius=1,material='Frict'))

def moveSphereToScene(): #delete the sphere from scene 1 and copy it to scene 0
    global s1
    if O.iter >1000 and O.thisScene==1:
        sbody=O.bodies[s1]
        O.bodies.erase(s1)
        O.switchToScene(0)
        O.bodies.append(sbody)
        s1=sbody.id
        moveSphere.dead=True

As you can see, if you set moveSphere.dead=True, the sphere will bounce on the wall as it should. But if you set moveSphere.dead=False, it will go through the wall after being moved to the other scene.
I am using the 2019-06-20.git-5b59e90 version of Yade, but I have the same problem with older git versions of Yade.

Question information

Language:
English Edit question
Status:
Solved
For:
Yade Edit question
Assignee:
No assignee Edit question
Solved by:
Léo Sénique
Solved:
2019-08-07
Last query:
2019-08-07
Last reply:
Léo Sénique (seniquel) said : #1

Hello again,
I think I have found the problem. It seems the way I tried to copy the sphere, erase it and add the same instance of that sphere to the simulation was screwing things up. Creating a new sphere with the same state and shape values fixes the problem:

def moveSphereToScene(): #delete the sphere from scene 1 and copy it to scene 0
    global s1
    if O.iter >1000 and O.thisScene==1:
        state=O.bodies[s1].state
        shape=O.bodies[s1].shape
        O.bodies.erase(s1)
        O.switchToScene(0)
        s1=O.bodies.append(sphere(center=state.pos,radius=shape.radius,material='Frict',color=color))
        O.bodies[s1].state=state
        O.bodies[s1].shape=shape
        moveSphere.dead=True