Heightmap physics (with DART) 🏔️

[chapulina]

🎉 New feature

Closes #237

Summary

Add heightmap support to the physics system.

Requires gazebosim/gz-physics#218

There's a resolution issue still to be solved on the physics side. It looks like only red spheres can stay on top of the heightmap 😉 🔴

Test it

Checklist

• Signed all commits for DCO
• Added tests: TODO
• 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

[chapulina]

This is ready for review. The heightmap behaves as expected when using the bullet collision checker:

I tested the above with these branches:

• gazebosim/gz-physics@main...chapulina/4/heightmap_detector, which includes Heightmaps 🏔️ gz-physics#218 and Support of closed kinematic chains gz-physics#25
• main...chapulina/5/heightmap_detector, which includes this and Set collision detector and solver from SDF #684

[chapulina]

Removed from beta, this can come in a minor release.

[ahcorde]

I can't see any test, do you plan to add some ?

Some minor style improvements

[vatanaksoytezer]

Just for logging purposes, I've tested this PR with a source built fortress and had been able to reproduce the example and also use custom heightmaps with it. It seemed to work pretty well for me. The only down side seems to be is being stuck with ogre rather than ogre2, cross referencing gazebosim/gz-rendering#187 for more information.

[scpeters]

we can test this branch with the ignition-physics4 prerelease if we merge the following: gazebo-tooling/gzdev#33

[scpeters]

the Ignition-physics4 prerelease homebrew bottles are built, so I restarted the macOS job

Test added 👍