colorbar matching plotted actors

[samcoveney]

I am plotting some tensors using an array of RGB values for coloring the ellipsoids, as follows:

scene = window.Scene()
sphere = get_sphere('repulsion724')
tensor_actor = actor.tensor_slicer(evals, evecs,
                                       sphere=sphere,
                                       scalar_colors=RGB,
                                       scale=1.0, norm=True)
scene.add(tensor_actor)

tmp = fury.colormap.colormap_lookup_table((0.0, 2.5e-3))  # but this has no connect to the colors RGB
scene.add(actor.scalar_bar(tmp, title="MD"))

window.show(scene)

But I cannot figure out how to add a scalar_bar that matches the RGB colors. I feel that this ought to be really simple, and that I must be missing something.

Thanks for your help. I can provide more comprehensive code if required.