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Change static model pose in `PostUpdate`

asked 2022-11-14 11:17:15 -0500

Myzhar gravatar image

updated 2022-11-14 11:20:56 -0500

Hi, I'm working on a System plugin in Gazebo Garden and I need to move a model in the PostUpdate callback.

I found the SetWorldPoseCmd function, but it requires a not constant Entity Component Manager and it cannot be used.

What is the correct way to set a new position for static objects?

I tried with this, but as expected it does not work:

gz::math::Pose3d newPose(mCalibX,mCalibY,mCalibZ,mCalibRoll,mCalibPitch,mCalibYaw);

gz::sim::EntityComponentManager ecm;

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answered 2022-11-16 14:05:30 -0500

azeey gravatar image

I think the main problem is that you're trying to set the model's pose form PostUpdate. The PostUpdate callback has a read-only access to the ECM. This is where systems update their internal state, not the state of the ECM. The PreUpdateis where systems are allowed to update the ECM and that's where you should try to set the pose of the model. See for more info.

Also, you shouldn't copy the ECM since any modifications you make to the copy will not affect the rest of the systems in the simulation.

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This is a really interesting note. I could not understand why ecm was read only in PostUpdate, but I was not considering the PreUpdate callback and it's scope. Thank you for pointing it.

Myzhar gravatar imageMyzhar ( 2022-11-22 14:18:25 -0500 )edit

answered 2022-11-15 16:36:31 -0500

jaguilar gravatar image

Hi Myzhar, my suggestion is to call SetWorldPoseCmd in the next PreUpdate, as PreUpdate provides a non-const reference to EntityComponentManager. As you correctly note, PostUpdate provides a const reference; as far as I know, this is by design.

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Thank you. I figured out my error now.

Myzhar gravatar imageMyzhar ( 2022-11-22 14:22:47 -0500 )edit

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Asked: 2022-11-14 11:17:15 -0500

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Last updated: Nov 16 '22