USD -> SDF: Parse Physics and generated SDF file

[ahcorde]

Signed-off-by: ahcorde ahcorde@gmail.com

🎉 New feature

Summary

Parse Physics and generated SDF file

Test it

If you have the isaac-sim-assets-2021.1.1 assets you can try for example:

usd2sdf isaac-sim-assets-2021.1.1//Robots/UR10/ur10.usd ur10.sdf

The expected output must look like:

<sdf version="1.7">
    <world name="ur10_world">
          <gravity>0 0 -9.8</gravity>
    </world>
</sdf>

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

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.

[codecov-commenter]

Codecov Report

Merging #863 (5d05f55) into sdf12 (b7447df) will decrease coverage by 0.02%.
The diff coverage is 69.04%.

❗ Current head 5d05f55 differs from pull request most recent head 966dc01. Consider uploading reports for the commit 966dc01 to get more accurate results

@@            Coverage Diff             @@
##            sdf12     #863      +/-   ##
==========================================
- Coverage   88.17%   88.15%   -0.03%     
==========================================
  Files          96      100       +4     
  Lines       14547    14629      +82     
==========================================
+ Hits        12827    12896      +69     
- Misses       1720     1733      +13     

Impacted Files	Coverage Δ
usd/src/cmd/usd2sdf.cc	85.18% <42.85%> (+12.45%)	⬆️
usd/src/usd_parser/USD2SDF.cc	50.00% <50.00%> (ø)
usd/src/usd_parser/USDWorld.cc	73.07% <73.07%> (ø)
usd/src/usd_parser/Parser.cc	73.33% <73.33%> (ø)
usd/src/usd_parser/USDPhysics.cc	85.00% <85.00%> (ø)
usd/src/usd_parser/USDMaterial.cc	64.90% <0.00%> (+1.98%)	⬆️
usd/src/usd_parser/USDData.cc	66.94% <0.00%> (+3.38%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b7447df...966dc01. Read the comment docs.

[scpeters]

usd2sdf isaac-sim-assets-2021.1.1//Robots/UR10/ur10.usd ur10.sdf

The expected output must look like:

<sdf version="1.7">
    <world name="ur10_world">
        <physics>
            <gravity>0 0 -9.8</gravity>
        </physics>
    </world>
</sdf>

this example doesn't look right to me. <gravity> should be directly under the <world>; it is not under <physics> in version 1.6+. In 1.5 and earlier, gravity was in the physics block, but not in newer versions.

• https://github.com/ignitionrobotics/sdformat/blob/sdf12/sdf/1.6/1_5.convert

[ahcorde]

usd2sdf isaac-sim-assets-2021.1.1//Robots/UR10/ur10.usd ur10.sdf

The expected output must look like:

<sdf version="1.7">
    <world name="ur10_world">
        <physics>
            <gravity>0 0 -9.8</gravity>
        </physics>
    </world>
</sdf>

this example doesn't look right to me. <gravity> should be directly under the <world>; it is not under <physics> in version 1.6+. In 1.5 and earlier, gravity was in the physics block, but not in newer versions.

• https://github.com/ignitionrobotics/sdformat/blob/sdf12/sdf/1.6/1_5.convert

Thank you @scpeters , I updated the PR

[adlarkin]

I still have a few more files to review, but here are a few questions that I have so far.

[adlarkin]

I made final iterations in 318eff9. Overall, LGTM, but I don't know much about tinyxml2, so @azeey or @scpeters, would you mind taking one final look before we merge this?

[adlarkin]

Thank you for the feedback and iterations, @ahcorde and @azeey! The new changes look good, and I think it's much easier to follow with sdf::Root. I just have one small comment, and will let @azeey take one last look before we merge.

[osrf-triage]

This pull request has been mentioned on Gazebo Community. There might be relevant details there:

https://community.gazebosim.org/t/new-ignition-releases-2022-04-13-fortress-edifice/1367/1