3d curved arrow in python

Question

How to draw a curved arrow in 3d, please? I mean something similar to the case in 2d:

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.patches as patches

fig, ax = plt.subplots()
plt.rcParams["figure.figsize"] = [10, 3]

plt.xlim(-50,150)
plt.ylim(-60,165)

style="Simple,tail_width=0.5,head_width=4,head_length=8"
kw = dict(arrowstyle=style)
a3 = patches.FancyArrowPatch((0, 0), (99, 100),connectionstyle="arc3,rad=-0.3", **kw)

for a in [a3]:
    plt.gca().add_patch(a)

plt.show()

Answer 1

You need to extend FancyArrowPatch. The idea is to intercept the 3D coordinates parameters. Other parameters are directly passed to the FancyArrowPatch artist.

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.patches import FancyArrowPatch


fig = plt.figure()
ax1 = fig.add_subplot(121)

ax1.set_xlim(-50,150)
ax1.set_ylim(-60,165)

style="Simple,tail_width=0.5,head_width=4,head_length=8"
kw = dict(arrowstyle=style)
a1 = FancyArrowPatch((0, 0), (99, 100),connectionstyle="arc3,rad=-0.3", **kw)

ax1.add_patch(a1)


from mpl_toolkits.mplot3d import proj3d

class Arrow3D(FancyArrowPatch):

    def __init__(self, xs, ys, zs, *args, **kwargs):
        FancyArrowPatch.__init__(self, (0, 0), (0, 0), *args, **kwargs)
        self._verts3d = xs, ys, zs

    def draw(self, renderer):
        xs3d, ys3d, zs3d = self._verts3d
        xs, ys, zs = proj3d.proj_transform(xs3d, ys3d, zs3d, renderer.M)
        self.set_positions((xs[0], ys[0]), (xs[1], ys[1]))
        FancyArrowPatch.draw(self, renderer)

ax2 = fig.add_subplot(122, projection="3d")

a2 = Arrow3D([0, 1], [0, 1], [0, 1], mutation_scale=20,
            lw=1, arrowstyle="-|>", color="k", connectionstyle="arc3,rad=-0.3")

ax2.add_artist(a2)

plt.show()

xs[0], ys[0], zs[0] is the starting point coordinates, xs[1], ys[1], zs[1] is the ending point coordinates.

Reference:

Plotting a 3d cube, a sphere and a vector in Matplotlib