C++ extensions, tests and example for Transform3D

[Wumpf]

What

• depends on C++ serialization support for most nested types, transform3d roundtrip test #2937
• part of C++ SDK V1 #2919
• fixes Transform3D + DisconnectedTransform migration to archetypes #2791

Roundtrip test is part of #2937
Does not yet work in viewer because of #2871

C++ extensions now get additional includes copied into the generated header

Extensions circle around making use of the Transform3D archetype easy.
Note that the willingness of a c++ compiler to convert arrays and floats to bool causes us quite a lot of extra overloads (luckily the added unit tests catches these and there are warnings emitted).
The amount of overloads introduced leaves a bit of a bad taste, but the expectation is that this is rather special to Transform3D. Some of the provided overloads may be generated in the future if a pattern emerges.

A bunch of code example added to demonstrate what it looks like now to use Transform3D:

// translation only
rr_stream.log("translated", rr::artchetypes::Transform3D({1.0f, 0.0f, 0.0f}));

// translation/rotation/uniform-scale
rr_stream.log(
    "rotated_scaled",
    rr::archetypes::Transform3D(
        rrd::RotationAxisAngle({0.0f, 0.0f, 1.0f}, rrd::Angle::radians(pi / 4.0f)),
        2.0f
    )
);

// 3x3 matrix
rec_stream.log(
    "translation_and_mat3x3/rotation",
    rr::archetypes::Transform3D({
        {1.0f, 4.0f, 7.0f},
        {2.0f, 5.0f, 8.0f},
        {3.0f, 6.0f, 9.0f},
    })
);

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I have tested demo.rerun.io (if applicable)

• PR Build Summary
• Docs preview
• Examples preview

[teh-cmc]

Splendid 👏

[nikolausWest]

I think the api looks really nice but have one thought. In Python we expose archetypes in the top level namespace (module) as well as under rerun.archetypes. That makes it possible to write some simple logging code without introducing the concept of archetypes yet. Is that something we might want to do in C++ as well? Might be a bit unclean for C++, but it is consistent with Python and we definitely want it there. Perhaps a bit magic but we could potentially do it inside rerun.hpp since that's what you include when you want the simple stuff (although that might be a little confusing)

[Wumpf]

would be very simple to do in rerun.hpp, yup. I'm leaning towards agreeing, a lil bit torn. If we do it here we should do so in Rust as well 🤔

[teh-cmc]

If we do it here we should do so in Rust as well 🤔

That's the plan yep. We don't do so yet because we were still "hiding" the new APIs until now (this wasn't a problem in python because we exposed those archetypes at the root of rr2, not rr).

The death of MsgSender will mark the beginning of archetypes at the root of the rerun crate.

[Wumpf]

then let's do it! :)

For C++ this means afaik just

namespace rerun {
   using namespace archetypes;
}

inside of rerun.hpp

follow-up pr ofc