Ray intersection simulation feature

[romulogcerqueira]

🎉 New feature

Related to gazebosim/gz-sensors#26

Summary

dartsim does support ray-based collisions via Bullet backend, which is also supported by gz-physics.

This PR creates a simulation feature to compute and retrieve ray castings. Also, it updates dartsim version >= 6.10, which fixes the issues when no ray hit.

This addition is useful for range-based applications (e.g. laser, altimeter etc.).

Test it

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

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[romulogcerqueira]

@ahcorde Comments have been addressed.

Thank you for the review!

[romulogcerqueira]

Any additional suggestions/reviews? @azeey @ahcorde @mxgrey @scpeters

[azeey]

Thanks for the contribution! Definitely a nice feature to have.

It's a shame that the ode collision detector doesn't support this since that's the default for Gazebo. Do you by any chance know if this would be straight forward to implement for the bullet-featherstone physics engine plugin (not collision detector). I ask because we've been making improvements to the plugin and it might become the default engine for Gazebo at some point.

[romulogcerqueira]

Thanks for the contribution! Definitely a nice feature to have.

It's a shame that the ode collision detector doesn't support this since that's the default for Gazebo. Do you by any chance know if this would be straight forward to implement for the bullet-featherstone physics engine plugin (not collision detector). I ask because we've been making improvements to the plugin and it might become the default engine for Gazebo at some point.

Thanks for your feedback, @azeey.

I'm not familiar with Bullet featherstone, however, it seems that this feature can be implemented for that plugin by creating a simulation feature that casts the world and calls the Bullet raycasting methods directly, e.g.:

  const auto worldInfo = this->ReferenceInterface<WorldInfo>(_worldID);

  const auto btFrom = convertVec(Eigen::Vector3d(0,0,0));
  const auto btTo = convertVec(Eigen::Vector3d(1,1,1));

  btCollisionWorld::ClosestRayResultCallback closestResults(btFrom, btTo);
  auto collisionWorld = worldInfo->world->getCollisionWorld();
  collisionWorld->rayTest(btFrom, btTo, closestResults);

[romulogcerqueira]

@azeey @ahcorde, please let me know if there are additional comments or if this PR is ready to go.

[romulogcerqueira]

PR rebased with last changes on gz-physics7 branch.

Comments have been addressed.

@azeey @ahcorde, please let me know if there are additional comments or if this PR is ready to go.

[romulogcerqueira]

@azeey All comments have been addressed.

[azeey]

@rakeshv24 PTAL

Concern has been addressed

[romulogcerqueira]

Thanks, @azeey.

Any idea when this might be released?

[peci1]

Hmm, Gazebo Classic also reported name of the collision that was hit. That was super useful for some scenarios, or e.g. for reporting laser retro/fiducial of the hit collision.

https://github.com/gazebosim/gazebo-classic/blob/e4b4d0fb752c7e43e34ab97d0e01a2a3eaca1ed4/gazebo/physics/ode/ODERayShape.cc#L126

Do you think it could be added?

[azeey]

Release is pending #659. If we do add this, it should be done soon since modifying RayIntersectionT would be a breaking change. Maybe we can add the additional parameters to RayIntersectionT without the actual implementation?

[peci1]

Maybe we can add the additional parameters to RayIntersectionT without the actual implementation?

That would be the quickest thinkable solution. I briefly looked into dart and the colliding body names should be available, so the implementation should be quite easy.

[peci1]

I guess "entity number (ID) of the collision" would be better than the name of the collision.