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compas-dev / compas_fab

Robotic fabrication package for the COMPAS Framework.
https://compas.dev/compas_fab/
MIT License
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PyBulletClient get_uid(robot) #302

Closed yijiangh closed 3 years ago

yijiangh commented 3 years ago

When I run the following script using PybulletClient at version 0.18.0:

with PyBulletClient(connection_type="gui", verbose=False) as client:
    robot = client.load_robot(urdf_filename)
    robot_uid = client.get_uid(robot)

It doesn't work because robot does not have the attribute attr.

The following script does work though:

with PyBulletClient(connection_type="gui", verbose=False) as client:
    robot = client.load_robot(urdf_filename)
    robot_uid = client.get_uid(client.get_cached_robot(robot))

This makes me wonder if this line and the lines followed should use robot.attr instead of robot.attributes? https://github.com/compas-dev/compas_fab/blob/main/src/compas_fab/backends/pybullet/client.py#L187

@beverlylytle Is this intended behavior to have users always work with the cached robot? Thanks!

Also, would you mind confirming that redirect_stdout is working (this line)?

When loading the robot with verbose=False, I still get the following printous:

argv[0]=
starting thread 0
started testThreads thread 0 with threadHandle 0000000000000170
argc=3
argv[0] = --unused
argv[1] =
argv[2] = --start_demo_name=Physics Server
ExampleBrowserThreadFunc started
Version = 4.6.0 NVIDIA 452.41
Vendor = NVIDIA Corporation
Renderer = GeForce GTX 1650/PCIe/SSE2
b3Printf: Selected demo: Physics Server
starting thread 0
started MotionThreads thread 0 with threadHandle 0000000000000AF8
MotionThreadFunc thread started
b3Printf: b3Warning[examples/Importers/ImportURDFDemo/BulletUrdfImporter.cpp,126]:

b3Printf: No inertial data for link, using mass=1, localinertiadiagonal = 1,1,1, identity local inertial frame
b3Printf: b3Warning[examples/Importers/ImportURDFDemo/BulletUrdfImporter.cpp,126]:

b3Printf: robotA_tool0
b3Printf: b3Warning[examples/Importers/ImportURDFDemo/BulletUrdfImporter.cpp,126]:

b3Printf: No inertial data for link, using mass=1, localinertiadiagonal = 1,1,1, identity local inertial frame
b3Printf: b3Warning[examples/Importers/ImportURDFDemo/BulletUrdfImporter.cpp,126]:

b3Printf: robotA_base
b3Printf: b3Warning[examples/Importers/ImportURDFDemo/BulletUrdfImporter.cpp,126]:

b3Printf: No inertial data for link, using mass=1, localinertiadiagonal = 1,1,1, identity local inertial frame
b3Printf: b3Warning[examples/Importers/ImportURDFDemo/BulletUrdfImporter.cpp,126]:

b3Printf: robotA_waam_tool
b3Printf: b3Warning[examples/Importers/ImportURDFDemo/BulletUrdfImporter.cpp,126]:

b3Printf: No inertial data for link, using mass=1, localinertiadiagonal = 1,1,1, identity local inertial frame
b3Printf: b3Warning[examples/Importers/ImportURDFDemo/BulletUrdfImporter.cpp,126]:

b3Printf: robotA_waam_tcp
beverlylytle commented 3 years ago

The pybullet assigned id is attached to the internal cached_robot and not an instance of compas_fab.robots.Robot or its compas_fab.robots.Robot.model. The cached_robot is an instance of compas.robots.RobotModel that is based on the compas_fab.robots.Robot.model but can be modified by the PyBullet client, and when it is, the pybullet id changes. So in a sense, yes, the user is working with the cached_robot, but we try to keep it behind the scenes as much as possible.

For me, the redirect_stdout is working. There is an exception to when it is enabled even if verbose=False is given, and that's when code is being run with pytest.

yijiangh commented 3 years ago

The pybullet assigned id is attached to the internal cached_robot and not an instance of compas_fab.robots.Robot or its compas_fab.robots.Robot.model.

Thanks for the explanation! So this is the canonical way to obtain the pybullet index of a given robot instance? 

robot_uid = client.get_uid(client.get_cached_robot(robot))

For me, the redirect_stdout is working. There is an exception to when it is enabled even if verbose=False is given, and that's when code is being run with pytest.

Aha, I am exactly encountering this with pytest 😃

beverlylytle commented 3 years ago

Thanks for the explanation! So this is the canonical way to obtain the pybullet index of a given robot instance?

robot_uid = client.get_uid(client.get_cached_robot(robot))

Yep.

I tried for a while to make redirect_stdout and pytest play together nicely, but couldn't manage.

yijiangh commented 3 years ago

Thanks! I guess not many users would need to access the pybullet body index, except for someone who is working on backend features 😄