Best way to plot an arrow in a MeshCatMechanisms visualizer?

I’d like to get a result similar to the force plotting done in this issue: Body wrench from forces applied at different points · Issue #589 · JuliaRobotics/RigidBodyDynamics.jl · GitHub. Unfortunately, the code for the actual visualization is not posted, so I’m trying to figure out how it was done.

I’ve been trying to use ArrowVisualizer from MeshCatMechanisms.jl:

using MeshCatMechanisms
using RigidBodyDynamics
using MeshCat
using GeometryBasics

vis = Visualizer()

mechanism = parse_urdf(urdf_file)


visuals = URDFVisuals(urdf_file)
mvis = MechanismVisualizer(mechanism, URDFVisuals(urdf_file), vis)

arrow_vis = ArrowVisualizer(vis)
settransform!(arrow_vis, Point(0.0, 0.0, 0.0), Vec(0.5, 0.5, 0.0))

Without the last line, the robot arm is situated correctly on its axis, but there’s no arrow:


But, after setting the transform, the arm AND the arrow are transformed.


It seems like I’m transforming both the “meshcat” visualization and the “arrow” visualization, possibly because they’re both linked to “vis”. Is there a way to transform just one? Or a better way to draw arrows or move this visualizer? Thanks in advance for any help.