在3D中绘制无法正确渲染

Question

我正在尝试在3D空间（在Python中）中绘制许多组件，但是渲染问题有问题。例如，下面的代码绘制了一个球体，其表面上有一些点，其赤道周围有一个环，以及各种箭头从原点射出。但是，matplotlib正在呈现所有点/球的顶部的箭头，并且基于在球体内部或外部的内部或外部没有正确的阴影。有更好的方法吗？我愿意在需要时使用其他图书馆，但没有成功地看起来不错。

import matplotlib.pyplot as plt
import numpy as np
from matplotlib.patches import FancyArrowPatch
from mpl_toolkits.mplot3d import proj3d

class Arrow3D(FancyArrowPatch):
    def __init__(self, xs, ys, zs, *args, **kwargs):
        super().__init__((0,0), (0,0), *args, **kwargs)
        self._verts3d = xs, ys, zs

    def do_3d_projection(self, renderer=None):
        xs3d, ys3d, zs3d = self._verts3d
        xs, ys, zs = proj3d.proj_transform(xs3d, ys3d, zs3d, self.axes.M)
        self.set_positions((xs[0],ys[0]),(xs[1],ys[1]))

        return np.min(zs)

def arrow3d(ax, length=1, width=0.05, head=0.2, headwidth=2,
                theta_x=0, theta_z=0, offset=(0,0,0), **kw):
    w = width
    h = head
    hw = headwidth
    theta_x = np.deg2rad(theta_x)
    theta_z = np.deg2rad(theta_z)

    a = [[0,0],[w,0],[w,(1-h)*length],[hw*w,(1-h)*length],[0,length]]
    a = np.array(a)

    r, theta = np.meshgrid(a[:,0], np.linspace(0,2*np.pi,30))
    z = np.tile(a[:,1],r.shape[0]).reshape(r.shape)
    x = r*np.sin(theta)
    y = r*np.cos(theta)

    rot_x = np.array([[1,0,0],[0,np.cos(theta_x),-np.sin(theta_x) ],
                      [0,np.sin(theta_x) ,np.cos(theta_x) ]])
    rot_z = np.array([[np.cos(theta_z),-np.sin(theta_z),0 ],
                      [np.sin(theta_z) ,np.cos(theta_z),0 ],[0,0,1]])

    b1 = np.dot(rot_x, np.c_[x.flatten(),y.flatten(),z.flatten()].T)
    b2 = np.dot(rot_z, b1)
    b2 = b2.T+np.array(offset)
    x = b2[:,0].reshape(r.shape); 
    y = b2[:,1].reshape(r.shape); 
    z = b2[:,2].reshape(r.shape); 
    ax.plot_surface(x,y,z, **kw)

# Create a sphere
r = 1
pi = np.pi
cos = np.cos
sin = np.sin
phi, theta = np.mgrid[0.0:pi:30j, 0.0:2.0*pi:30j]
x = r*sin(phi)*cos(theta)
y = r*sin(phi)*sin(theta)
z = r*cos(phi)

#Set colours and render
fig = plt.figure(figsize=(8,8))
ax = fig.add_subplot(111, projection='3d')

ax.plot_surface(x, y, z,  rstride=1, cstride=1, color='c', alpha=0.3, linewidth=0)

theta = np.linspace(0, 2*np.pi, 100)
ax.plot(np.cos(theta), np.sin(theta), 0, 'k', linewidth=4)

ax.scatter(x,y,z,color="k",s=20)

eig_vec = np.array([[1., 0., 0.],
       [0., 1., 0.],
       [0., 0., 1.]])
for v in eig_vec:
    #ax.plot([mean_x,v[0]], [mean_y,v[1]], [mean_z,v[2]], color='red', alpha=0.8, lw=3)
    #I will replace this line with:
    a = Arrow3D([0, v[0]], [0, v[1]], 
                [0, v[2]], mutation_scale=20, 
                lw=3, arrowstyle="-|>", color="r")
    ax.add_artist(a)

arrow3d(ax, length=2.5, width=0.02, head=0.1, headwidth=1.5, offset=[0,0,0], 
        theta_x=40,  color="crimson")

ax.set_xlim([-1,1])
ax.set_ylim([-1,1])
ax.set_zlim([-1,1])
ax.set_aspect("auto")
plt.tight_layout()
plt.show()