How to trigger a stereo camera on Gazebo Ignition with ROS2 ?

edit

Hello,

I'd like to trigger a stereo acquisition from ROS Galactic with Gazebo Ignition (Fortress).
I don't find any documentation. Could someone provide me an example ?
I've found https://github.com/ros-simulation/gaz... but I'm not sure if those plugins are for ignition or gazebo classic...

Thanks in advance

Update

Ignition plugins are here: https://github.com/gazebosim/gz-sim/. Sensors have been fused into a single Sensor.cc. To create a stereo camera you need two <sensor> tags with type "camera" as described here: https://github.com/gazebosim/gz-sim/b...</sensor>

The Load() function parses the <camera> tag: https://github.com/gazebosim/sdformat...</camera>

To trigger cameras, you need to set the <triggered> tag to true and give a <trigger_topic>.
In the end, my urdf looks like this:

<sensor type="camera" name="right">
  <update_rate>10.0</update_rate>
  <always_on>true</always_on>
  <ignition_frame_id>camera_link_optical</ignition_frame_id>
  <pose>0 -0.12 0 0 0 0</pose>
  <topic>/model/mmx/stereo_camera/right/image_raw</topic>
  <camera name="right">
    <triggered>true</triggered>
    <trigger_topic>/trigger</trigger_topic>
    <horizontal_fov>1.3962634</horizontal_fov>
    <image>
        <width>600</width>
        <height>600</height>
        <format>R8G8B8</format>
    </image>
    <clip>
        <near>0.02</near>
        <far>300</far>
    </clip>
  </camera>
</sensor>

<sensor type="camera" name="left">
  <topic>/model/mmx/stereo_camera/left/image_raw</topic>
  <update_rate>10.0</update_rate>
  <always_on>true</always_on>
  <ignition_frame_id>mmx/camera_link_optical</ignition_frame_id>
  <pose>0 0 0 0 0 0</pose>
  <camera name="left">
    <triggered>true</triggered>
    <trigger_topic>/trigger</trigger_topic>
    <horizontal_fov>1.3962634</horizontal_fov>
    <image>
        <width>600</width>
        <height>600</height>
        <format>R8G8B8</format>
    </image>
    <clip>
        <near>0.02</near>
        <far>300</far>
    </clip>
  </camera>
</sensor>

There is no message on the topic ign topic -t /model/mmx/stereo_camera/left/image_raw -e which means the camera is in triger mode (not constantly streaming messages on the topic).

But the trigger_topic doesn't appear when I list topics with ign topic -l
And if I pusblish a message on the trigger_topic with ign topic -t "/trigger" -m ignition.msgs.Empty -p " ", cameras are not triggered (still no image message).