What is the default value of physicsClientId?

Question

More or less all functions of pyBullet take an optional argument physicsClientId which is needed when multiple instances are running in parallel.

When writing custom functions that call pybullet internally, I would like to provide this as an optional argument there as well. So I tried the following:

def my_func(..., physicsClientId=None):
    pybullet.some_func(
        ...,
        physicsClientId=physicsClientId,
    )

However, when I call this without specifying the ID, I get

TypeError: an integer is required (got type NoneType)

so None is obviously the wrong default value. As it want's an integer, I assume it is something like 0 or -1 but I would like to know if there is an official answer to this (in the pyBullet documentation, there are typically no default values specified for optional arguments).

Answer 1

From looking at the code (pybullet.c), it seems the default is 0.

And indeed, def my_func(..., physicsClientId=0) is working.