Simple built-in URDF loader

[emilk]

Related

• Closes Support URDF #10114

What

Add built-in support for loading .urdf files.

Shortcomings

• Is missing support for cylinders: Support for more 2D and 3D primitives #1361
• Logging both visual and collision meshes leads to Z fighting. Could be solved with Allow logging visible & interative to datastore #6541
• We get very deep entity trees (see Support for "Derived" Transforms #1533)
• No support for external mesh files on web

Testing

You can use these urdf meshes:

• https://github.com/unitreerobotics/unitree_ros/tree/master/robots/g1_description
• https://github.com/TheRobotStudio/SO-ARM100/blob/main/Simulation/SO100/so100.urdf
• https://github.com/Daniella1/urdf_files_dataset

TODO

• Some web support
• Add support for other primitives than meshes
• Log colors from URDF as albedo_factor overrides to Rerun
• Try drag-dropping in an .urdf file in the native viewer
• Try drag-dropping in an .urdf file in the web viewer
• Handle non-relative mesh paths
• Add an URDF to git lfs for testing?
• Test animating a robot arm by logging joint angles separately

[github-actions]

Web viewer built successfully. If applicable, you should also test it:

• I have tested the web viewer

Result	Commit	Link	Manifest
✅	aa6eb07	https://rerun.io/viewer/pr/10105	+nightly +main

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[oxkitsune]

It's been a while since I had my computer graphics course, but I think Gazebo assumes linear colours.
This page on the colour model mentions the it's rendered using the Blinn-Phong shading model, which I think implies it's linear.

There's also this 10 year old issue on the RViz repo: ros-visualization/rviz#515 that mentions it's missing gamma correction 😄