gz-sim: Python interfaces

[audrow]

Setup

• Os: Ubuntu Focal
• BuildType: Binary

Links

• Live
• Source

Checks

• Instructions work
• Images (if there are any) match the result

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You can find the code used to generate this test case here

[AndrejOrsula]

[Should work in source build now] Using binary install, the example works only if gz.sim7 Python module is changed to gz.sim.

- from gz.sim7 import TestFixture, World, world_entity
+ from gz.sim  import TestFixture, World, world_entity

However, I noticed gazebosim/gz-sim#1716. Therefore, it should be fixed now in the source build - without needing to change this Python script.

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Another thing is that my output is a bit different compared to the output in the tutorial and I get an [Err], but I am not sure what could be causing it. The important output is still the same, so maybe it is okay?

[Msg] Serving entity system service on [/entity/system/add]
[Dbg] [Physics.cc:869] Loaded [gz::physics::dartsim::Plugin] from library [/usr/lib/x86_64-linux-gnu/gz-physics-6/engine-plugins/libgz-physics-dartsim-plugin.so]
[Dbg] [SystemManager.cc:58] Loaded system [gz::sim::systems::Physics] for entity [1]
[Msg] Loaded level [3]
[Msg] Serving world controls on [/world/gravity/control], [/world/gravity/control/state] and [/world/gravity/playback/control]
[Msg] Serving GUI information on [/world/gravity/gui/info]
[Msg] World [gravity] initialized with [default_physics] physics profile.
[Msg] Serving world SDF generation service on [/world/gravity/generate_world_sdf]
[Msg] Serving world names on [/gazebo/worlds]
[Msg] Resource path add service on [/gazebo/resource_paths/add].
[Msg] Resource path get service on [/gazebo/resource_paths/get].
[Msg] Resource path resolve service on [/gazebo/resource_paths/resolve].
[Msg] Resource paths published on [/gazebo/resource_paths].
[Msg] Server control service on [/server_control].
[Err] [Conversions.cc:1726] Tried to convert SDF [world] into [plugin]
[Msg] Found no publishers on /stats, adding root stats topic
[Msg] Found no publishers on /clock, adding root clock topic
[Dbg] [SimulationRunner.cc:507] Creating PostUpdate worker threads: 2
[Dbg] [SimulationRunner.cc:518] Creating postupdate worker thread (0)
World entity is  1
Gravity  0 0 -9.8
Entity for falling model is:  4
Post update sim time:  0:00:01
iterations  1000
post_iterations  1000
pre_iterations  1000

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Fixed URL to the example folder via gazebosim/gz-sim#1721