Plotting Splines

This example demonstrates add_spline() and add_splines() — the methods for rendering single polyline paths and bundles of splines from 1-D and N-D spherical coordinate arrays.

import numpy as np
from pyvisual import Plot3d

Single Spline

add_spline() draws a single line through a sequence of \((r, \theta, \phi)\) points. The example below traces an equatorial Archimedean spiral: the longitude \(\phi\) increases uniformly as the radial distance \(r\) grows from \(1\,R_\odot\) to \(30\,R_\odot\), approximating a Parker spiral in the ecliptic plane. The spline is colored by \(r\).

r = np.linspace(1, 30, 100)
t = np.repeat(np.pi / 2, 100)
p = np.linspace(0, 2 * np.pi, 100)

plotter = Plot3d(off_screen=True, window_size=(500, 500))
plotter.show_axes()
plotter.add_sun()
plotter.add_spline(r, t, p, r, line_width=5)
plotter.show()

Static Scene

Interactive Scene

Bundle of Splines

add_splines() renders multiple splines from N-D coordinate arrays. Here, 10 meridional arcs connect the north and south poles at evenly spaced longitudes, tracing the surface of a sphere of radius \(5\sin\theta\,R_\odot\). The coordinate arrays have shape (10, 100); axis=1 declares that axis 1 (length 100) traces each individual spline path and axis 0 (length 10) enumerates the distinct meridians. Each spline is colored by its index.

n_lines, n_pts = 10, 100
r = np.tile(5 * np.sin(np.linspace(0, np.pi, n_pts)), (n_lines, 1))
t = np.tile(np.linspace(0, np.pi, n_pts), (n_lines, 1))
p = np.tile(np.linspace(0, 2 * np.pi, n_lines)[:, None], (1, n_pts))
data = np.arange(n_lines)

plotter = Plot3d(off_screen=True, window_size=(500, 500))
plotter.show_axes()
plotter.add_sun()
plotter.add_splines(r, t, p, data, axis=1, show_scalar_bar=False)
plotter.show()

Static Scene

Interactive Scene