Snake
"""Simple example to calculate three stacked cubes"""
import os
import compas
import compas_cra
from compas_cra.datastructures import CRA_Assembly
from compas_cra.algorithms import assembly_interfaces_numpy
from compas_cra.equilibrium import cra_solve, cra_penalty_solve
from compas_cra.viewers import cra_view
mu = 0.7
dispbnd = 1e-1
overlap = 1e-4 * 0
d = 1
FILE_I = os.path.join(compas_cra.SAMPLE, "snake.json")
assembly = compas.json_load(FILE_I)
assembly = assembly.copy(cls=CRA_Assembly)
assembly.set_boundary_conditions([0])
# assembly.delete_node(1)
# assembly.delete_node(2)
# assembly.delete_node(3)
assembly_interfaces_numpy(assembly, amin=1e-4, tmax=1e-2)
cra_solve(assembly, verbose=True, density=d, d_bnd=dispbnd, eps=overlap, mu=mu)
# cra_penalty_solve(assembly, verbose=True, density=d, d_bnd=dispbnd, eps=overlap, mu=mu)
cra_view(
assembly,
resultant=True,
nodal=True,
grid=True,
weights=False,
displacements=True,
dispscale=1,
scale=0.1 / d,
)