Set max contacts for collision pairs

[iche033]

🎉 New feature

Depends on gazebosim/gz-physics#582

Summary

Set max_contacts physics parameter in physics engines that support this feature. See gazebosim/gz-physics#582 for support in dartsim's ode collision detector.

Test it

Here's an example test world: contacts.sdf.

The test world has a large box with an ellipsoid inside. The contact points are visualized in blue:

Before: No max contacts set. Many contacts detected. Low RTF (~30%)

After: Max contacts set based on SDF default value (20). Limited to 20 contacts. High RTF (~9X%)

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]

@caguero to make a release of gz-physics6 to unblock this PR.

[guest43]

Hi, when I run this example in Gazebo Harmonic, i don't get the "after" result with only 20 contacts. It still appears as the before result. This is true if I explicitly state the <max_contacts> in the world file as well. I am running gz physics from ROS2 installed vendor packages which appears to be the latest release (gz-physics 7.2.0). From a look at the gz-physics repo, max_contacts appears to be implemented.. has this feature indeed been released? Am I missing something?

-User

[iche033]

has this feature indeed been released?

we still need to merge this PR, forward port to the gz-sim8 branch, and make another gz-sim8 release for Harmonic

[guest43]

we still need to merge this PR, forward port to the gz-sim8 branch, and make another gz-sim8 release for Harmonic

Thanks for the info. If I wanted to use this feature in advance of its official release, do you know how I would go about that?

If I'm reading this PR and status board correctly, it looks like this feature has been merged into gz-sim7 (Garden). I have installed both the stable and nightly binary releases of Garden in a container. The gz-physics6 version installed in the container is 6.6.0. I am assuming this corresponds to the gz-physics6 branch of the github repo. However, I still can't run the new feature. Can you point me in the right direction?

[iche033]

The changes in gz-sim7 has not been released yet. To test this you'll need to build gz-sim7 from source

I don't think we are currently building nightlies for gz-sim7 so I think the gz-sim7 nightly you have is probably quite old now.