Support configuring particle scatter ratio in particle emitter system

[iche033]

Signed-off-by: Ian Chen ichen@osrfoundation.org

🎉 New feature

Summary

depends on gazebosim/gz-rendering#269

This PR extends the particle_emitter system to support configuring the particle scatter ratio parameter by reading the value from SDF: <particle_scatter_ratio>. Currently only supports setting this parameter on load.

Test it

You can test using ign-gazebo with the sensor_particles_scattering.sdf world file. The first time you run it, it'll download the Fog Emitter model but you won't see any fog.

ign gazebo -r sensor_particles_scattering.sdf

By default it's off so you'll need to enable it, either by

• changing the <emitting> field to true in ~/.ignition/fuel/fuel.ignitionrobotics.org/openrobotics/models/fog emitter/<version_number>/model.sdf and relaunching ign-gazebo, or
• publishing a cmd to it:

  ign topic -t "/model/fog_generator/particle_emitter/fog_generator" -m ignition.msgs.ParticleEmitter -p "emitting: {data: 1}"
  

Enable lidar visualization through the Visualize Lidar gui plugin (top right menu -> Visualize Lidar). Here is what you should see:

Pay attention to the particle effects in depth, rgbd cameras and lidars. Now change particle scatter ratio by modifying ~/.ignition/fuel/fuel.ignitionrobotics.org/openrobotics/models/fog emitter/<version_number>/model.sdf and adding <particle_scatter_ratio>0.01</particle_scatter_ratio> under <emitter>.

Run ign-gazebo with sensor_particles_scattering.sdf again to see that the new scatter ratio in effect. The fog particles should appear to be less dense (noisy) in the depth / rgbd cameras and lidar visualizations.

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

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[codecov]

Codecov Report

Merging #674 (34b31c0) into ign-gazebo4 (2d6c0fa) will decrease coverage by 0.01%.
The diff coverage is 46.15%.

@@               Coverage Diff               @@
##           ign-gazebo4     #674      +/-   ##
===============================================
- Coverage        65.51%   65.50%   -0.02%     
===============================================
  Files              237      237              
  Lines            17197    17210      +13     
===============================================
+ Hits             11267    11273       +6     
- Misses            5930     5937       +7     

Impacted Files	Coverage Δ
src/rendering/SceneManager.cc	22.49% <0.00%> (-0.21%)	⬇️
src/systems/particle_emitter/ParticleEmitter.cc	66.18% <100.00%> (+1.52%)	⬆️

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[adlarkin]

As a reminder, we will need to update src/rendering/SceneManager.cc to use the new API in gazebosim/gz-rendering#275 when we forward port this to Edifice. I think we can go ahead and merge this now though, unless there's something else we're waiting on.

[iche033]

added todo note on merging forward. 34b31c0