Print auto inertial values with gz sdf --print --expand-auto-inertials

[scpeters]

🎉 New feature

Closes #1348

Summary

The ability to automatically compute inertial values by setting the //inertial/@auto attribute to true is very convenient, but it is difficult to see what inertial values were computed. This adds a --expand-auto-inertials argument to gz sdf --print to show the auto-computed inertial values in the printed output.

To enable this behavior, a new enum value SAVE_CALCULATION_IN_ELEMENT is added to ConfigureResolveAutoInertials in ParserConfig.hh, and the Link will store auto-computed inertial values directly in its sdf::Element when this configuration is set.

I am seeing a failing test on macOS locally but want to see if it is an issue on other platforms. EDIT: fixed in 2ffda3d.

Test it

• Run INTEGRATION_link_dom to verify the functionality of the Link class with SAVE_CALCULATION_IN_ELEMENT
• Run UNIT_gz_TEST to verify the --expand-auto-inertials parameter to gz sdf --print
• If you build this in a colcon workspace with gz-tools2, then gz sdf --print test/sdf/inertial_stats_auto.sdf with and without --expand-auto-inertials should demonstrate the feature.

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• 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

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[azeey]

Can you mention that this won't work for meshes.

[scpeters]

in f32393b I've added a bit to the doc-string for gz sdf --print --expand-auto-inertials that mesh inertial data isn't computed. here's the output I see (with some adjusted whitespace):

$ gz sdf --print test/sdf/mesh_auto_inertial.sdf --expand-auto-inertials
Warning [Utils.cc:115] Collision is missing a <density> child element.
 Using a default density value of 1000.000000 kg/m^3.
Warning [Utils.cc:115] Custom moment of inertia calculator for meshes
 not set via sdf::ParserConfig::RegisterCustomInertiaCalc,
 using default inertial values.
<sdf version='1.12'>
  <model name='test_model'>
    <link name='L1'>
      <inertial auto='true'>
        <pose>0 0 0 0 0 0</pose>
        <mass>1</mass>
        <inertia>
          <ixx>1</ixx>
          <ixy>0</ixy>
          <ixz>0</ixz>
          <iyy>1</iyy>
          <iyz>0</iyz>
          <izz>1</izz>
        </inertia>
      </inertial>
      <collision name='collision'>
        <geometry>
          <mesh>
            <uri>box.dae</uri>
          </mesh>
        </geometry>
      </collision>
    </link>
  </model>
</sdf>