collision not happen

[lucattyy]

I put a ball and a box in the simulation and have them move towards each other at first. However, when they meet each other they don't collide but penetrate. How to make a collision happen??

Here is the code.

Code

import torch
import nimblephysics as nimble
world = nimble.simulation.World()
world.setGravity([0, -9.81, 0])
world.setTimeStep(0.01)
world.setFallbackConstraintForceMixingConstant(0.001)
world.setPenetrationCorrectionEnabled(True)

box = nimble.dynamics.Skeleton()
boxJoint, boxBody = box.createTranslationalJoint2DAndBodyNodePair()
boxShape = boxBody.createShapeNode(nimble.dynamics.BoxShape([.1, .1, .1]))
boxVisual = boxShape.createVisualAspect()
boxVisual.setColor([0.5, 0.5, 0.5])
world.addSkeleton(box)

sphere = nimble.dynamics.Skeleton()
sphereJoint, sphereBody = sphere.createTranslationalJoint2DAndBodyNodePair()
sphereShape = sphereBody.createShapeNode(nimble.dynamics.SphereShape(.2))
sphereVisual = sphereShape.createVisualAspect()
sphereVisual.setColor([0., 0., 1, 1])
world.addSkeleton(sphere)

initialState = torch.tensor([0, 0, 0, 2, 0, 5, 0, 0])
action = torch.zeros((world.getActionSize()))
state = initialState
states = []
sphere.enableSelfCollisionCheck()
box.enableSelfCollisionCheck()

for _ in range(300):
state = nimble.timestep(world, state, action)
states.append(state)

gui = nimble.NimbleGUI(world)
gui.serve(8080) # host the GUI on localhost:8080
gui.loopStates(states) # tells the GUI to animate our list of states
gui.blockWhileServing() # block here so we don't exit the program