using coal(hpp-fcl) and pinocchio

[viprob-ai]

Bug description

Cannot import coal and pinocchio

I have built coal from source and pinocchio installed using pip install pin

coal : version > 3.0.0
pinocchio : version >2.7.0

import coal
import pinocchio as pin

Error

    from .pinocchio_pywrap import *
AttributeError: 'NoneType' object has no attribute '__dict__'. Did you mean: '__dir__'?

Expected behavior

import coal
import pinocchio as pin

is there any conflict or how to use both if needed ?

Code

import coal
import pinocchio as pin

Error

    from .pinocchio_pywrap import *
AttributeError: 'NoneType' object has no attribute '__dict__'. Did you mean: '__dir__'?

If you revert the order of import then coal throws error

    from .coal_pywrap import *  # noqa
SystemError: initialization of coal_pywrap raised unreported exception

System

• OS : ubuntu 22.04
• Pinocchio version: 2.7.0

[nim65s]

the pin package you installed with pip already comes with hpp-fcl dependency. There is no need to build coal.

[viprob-ai]

But some of the attributes does not exist under current hpp-fcl like below [code snippet from coal repo]

coal.Transform3s()
contact.getNearestPoint1()

so built the library to make use of that and also to use it as standalone module.

import numpy as np
import coal
# Optional:
# The Pinocchio library is a rigid body algorithms library and has a handy SE3 module.
# It can be installed as simply as `conda -c conda-forge install pinocchio`.
# Installing pinocchio also installs coal.
import pinocchio as pin

def loadConvexMesh(file_name: str):
    loader = coal.MeshLoader()
    bvh: coal.BVHModelBase = loader.load(file_name)
    bvh.buildConvexHull(True, "Qt")
    return bvh.convex

if __name__ == "__main__":
    # Create coal shapes
    shape1 = coal.Ellipsoid(0.7, 1.0, 0.8)
    shape2 = loadConvexMesh("../path/to/mesh/file.obj")

    # Define the shapes' placement in 3D space
    T1 = coal.Transform3s()
    T1.setTranslation(pin.SE3.Random().translation)
    T1.setRotation(pin.SE3.Random().rotation)
    T2 = coal.Transform3s();
    # Using np arrays also works
    T1.setTranslation(np.random.rand(3))
    T2.setRotation(pin.SE3.Random().rotation)

    # Define collision requests and results
    col_req = coal.CollisionRequest()
    col_res = coal.CollisionResult()

    # Collision call
    coal.collide(shape1, T1, shape2, T2, col_req, col_res)

    # Accessing the collision result once it has been populated
    print("Is collision? ", {col_res.isCollision()})
    if col_res.isCollision():
        contact: coal.Contact = col_res.getContact(0)
        print("Penetration depth: ", contact.penetration_depth)
        print("Distance between the shapes including the security margin: ", contact.penetration_depth + col_req.security_margin)
        print("Witness point shape1: ", contact.getNearestPoint1())
        print("Witness point shape2: ", contact.getNearestPoint2())
        print("Normal: ", contact.normal)

    # Before running another collision call, it is important to clear the old one
    col_res.clear()

[nim65s]

Then you can either:

1. compile both coal and pinocchio yourself
2. use a package manager where pinocchio is already using coal (I think the options here are AUR, brew, conda, nix, robotpkg)
3. wait for pip to provide coal (it's almost done, but I can't finish this during the hollidays)

[viprob-ai]

@nim65s Thanks for quick response and update.

will try suggested options and yes will wait for pip release 👍 in case could not succeed with other options.