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[Jan Stránský <question670078@xxxxxxxxxxxxxxxxxxxxx>]

Question #670078 on Yade changed:
https://answers.launchpad.net/yade/+question/670078

    Status: Open => Answered

Jan Stránský proposed the following answer:
Hi,

> But I am unsure how I can make my spherePack dense after filling the predicate?
> And since my body of spheres is also spherical, it seems to me that a compression from 6 different planes will only distort my sphere.

one the approach of randomDensePack is to create a densePacking and than
"crop" it according to predicate

> it is suggested to change the source code for spherePack, how can this
be done?

e.g.:

####################################
def myMakeCloud(mn,mx,mu,sigma,rMin,num,maxTry=1000,seed=0): # [1]
   import random
   import numpy as np
   random.seed(seed)
   mn = Vector3(mn)
   mx = Vector3(mx)
   size = mx-mn
   rnd = random.random
   ret = []
   radii = np.random.normal(mu,sigma,num)
   radii = map(lambda r: max(r,rMin), radii)
   for r in radii:
      for t in xrange(maxTry):
         c = Vector3([mn[axis] + r + (size[axis]-2*r)*rnd() for axis in (0,1,2)])
         packSize = len(ret)
         overlap = False
         for pc,pr in ret:
            if pow(pr+r,2) >= (pc-c).squaredNorm():
               overlap = True
               break
         if not overlap:
            ret.append((c,r))
            break
      if t == maxTry:
         raise RuntimeError, "WRNING: Exceeded {} tries to insert non-overlapping sphere to packing. Only {} spheres were added, although you requested {}.".format(maxTry,i,num)
   return pack.SpherePack(ret)

def myRandomDensePack(predicate,mu,sigma,rMin,material=-1,spheresInCell=300,color=None,returnSpherePack=None,seed=0): # [2]
   dim=predicate.dim()
   if max(dim)==float('inf'): raise RuntimeError("Infinite predicate and no dimension of packing requested.")
   center=predicate.center()
   fullDim=dim
   cloudPorosity=0.25
   beta,gamma=fullDim[1]/fullDim[0],fullDim[2]/fullDim[0]
   N100=spheresInCell/cloudPorosity
   x1=mu*(1/(beta*gamma)*N100*(4/3.)*pi)**(1/3.)
   y1,z1=beta*x1,gamma*x1; vol0=x1*y1*z1
   O.switchScene(); O.resetThisScene() ### !!
   O.periodic=True
   O.cell.setBox((x1,y1,z1))
   O.materials.append(FrictMat(young=3e10,density=2400))
   sp = myMakeCloud(Vector3().Zero,O.cell.refSize,mu,sigma,rMin,spheresInCell,seed=seed)
   O.engines=[ForceResetter(),InsertionSortCollider([Bo1_Sphere_Aabb()],verletDist=.05*mu),InteractionLoop([Ig2_Sphere_Sphere_ScGeom()],[Ip2_FrictMat_FrictMat_FrictPhys()],[Law2_ScGeom_FrictPhys_CundallStrack()]),PeriIsoCompressor(charLen=2*mu,stresses=[-100e9,-1e8],maxUnbalanced=1e-2,doneHook='O.pause();',globalUpdateInt=1,keepProportions=True),NewtonIntegrator(damping=.6)]
   O.materials.append(FrictMat(young=30e9,frictionAngle=.5,poisson=.3,density=1e3))
   for s in sp: O.bodies.append(utils.sphere(s[0],s[1]))
   O.dt=utils.PWaveTimeStep()
   O.run(); O.wait()
   sp=SpherePack(); sp.fromSimulation()
   O.switchScene() ### !!
   sp.cellFill(Vector3(fullDim[0],fullDim[1],fullDim[2]))
   return filterSpherePack(predicate,sp,material=material,color=color,returnSpherePack=returnSpherePack)

mu, sigma = 20,2
rMin = .25*mu
pred = pack.inSphere(center=(0,0,0),radius=100)
sphs = myRandomDensePack(pred,mu,sigma,rMin,spheresInCell=300)
O.bodies.append(sphs)
####################################

cheers
Jan

[1] https://answers.launchpad.net/yade/+question/667571
[2] https://github.com/yade/trunk/blob/master/py/pack/pack.py#L454

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