Plot Truss-like FEA Solution with Cylinders

Plot connections between points in 3D as cylinders, colored by scalars. Lines are created in a pyvista.PolyData and then rendered as cylinders.

import numpy as np

import pyvista

Define the points and elements of the truss. Call them nodes here as it comes from finite element analysis.

nodes = [
    [0.0, 0.0, 0.0],
    [0.0, 1.0, 0.0],
    [4.0, 3.0, 0.0],
    [4.0, 0.0, 0.0],
    [0.0, 1.0, 2.0],
    [4.0, 1.0, 2.0],
    [4.0, 3.0, 2.0],
]


edges = np.array(
    [
        [0, 4],
        [1, 4],
        [3, 4],
        [5, 4],
        [6, 4],
        [3, 5],
        [2, 5],
        [5, 6],
        [2, 6],
    ],
)

# We must "pad" the edges to indicate to vtk how many points per edge
padding = np.empty(edges.shape[0], int) * 2
padding[:] = 2
edges_w_padding = np.vstack((padding, edges.T)).T
edges_w_padding

array([[2, 0, 4],
       [2, 1, 4],
       [2, 3, 4],
       [2, 5, 4],
       [2, 6, 4],
       [2, 3, 5],
       [2, 2, 5],
       [2, 5, 6],
       [2, 2, 6]])

Plot the truss while rendering the lines as tubes.

mesh = pyvista.PolyData(nodes, edges_w_padding)

colors = range(edges.shape[0])
mesh.plot(
    scalars=colors,
    render_lines_as_tubes=True,
    style='wireframe',
    line_width=10,
    cmap='jet',
    show_scalar_bar=False,
    background='w',
)