Legend not shown

[danieljuschus]

Adding a legend by making the following changes to the usage example doesn't work, i.e. no legend is visible:

...
## Add mesh to the plotter
plotter.add_mesh(mesh, scalars='myscalar', cmap='bwr', line_width=1, label="cube")
plotter.add_legend()
...

No errors are being shown.

On the other hand, when calling plotter.show() before st.session_state.model = HTML_stpyvista(plotter), the legend is visible in the separate pyvista window:

[edsaac]

stpyvista uses the pythreejs backend to convert the pyvista plotter into an HTML that is then passed to streamlit. This has some limitations, like adding a colorbar or text (check https://docs.pyvista.org/user-guide/jupyter/pythreejs.html#caveats). When plotter.show() opens a new window, this means that pyvista is using a "standard desktop VTK render window" (https://docs.pyvista.org/user-guide/jupyter/index.html#usage-with-pyvista).

I'll try checking if there is a workaround, as threejs does support labels (e.g., https://threejs.org/examples/css2d_label).

[edsaac]

With the panel backend (from stpyvista>=0.0.7), colorbars and titles can be added to the plotter. They are not totally legends, but can serve as a way to annotate stuff in the plotter.

## Add mesh to the plotter
plotter.add_mesh(mesh, cmap='bwr', line_width=1,)
plotter.add_scalar_bar()
plotter.add_title("My cube", color="black", font_size=14)