Moon with Rotating Earth

Animation control:

Visualization	Frame Value
Surface geometry	constant
Surface position	rotation transform per frame
Surface color	constant
Shading and highlighting	fixed to the coordinate axis
Axis coordinate	constant

Based on the static plot from the Geometric and Color Image Mapping example.

Copies of the geometric and colored surface were used so that those two operations need not be repeated for each frame, only the rotation and shading.

import copy
import numpy as np
from matplotlib import pyplot as plt
from matplotlib.animation import FuncAnimation
import s3dlib.surface as s3d

#.. Earth-Moon Animation

# 0. Define animation control parameters ............................

totalTime, f_domain, numFrames = 6, (0.0,360), 60   # time in seconds
frames=np.linspace(*f_domain, numFrames, endpoint=False)
interval = int(1000.0*totalTime/numFrames)          # milliseconds

# 2. Setup and map surfaces .........................................
start_theta = 0
rez=6
lightDirection = [1,0.8,1]

moon = s3d.SphericalSurface(rez-1)
moon.map_color_from_image('data/moon.png')
moon.shade(contrast=2,direction=lightDirection)
moon.transform(scale=[.4,.4,.4],translate=[-2,1,0.5])
# .......
earth = s3d.SphericalSurface(rez)
earth.map_color_from_image('data/earth.png')
earth.map_geom_from_image('data/elevation.png',0.06)
earthcopy = copy.copy(earth)
earthcopy.transform(scale=[1.2,1.2,1.2], translate=[.5,-.25,0],rotate=s3d.eulerRot(start_theta,0) )
earthcopy.shade(contrast=1.7,direction=lightDirection)
 
# 3. Construct figure, add surfaces, and plot ......................

fig = plt.figure(figsize=plt.figaspect(1), facecolor='k' )
ax = fig.add_subplot(111, projection='3d', facecolor='k', aspect='equal')
minmax = (-1,1)
ax.set(xlim=minmax, ylim=minmax, zlim=minmax)
ax.set_axis_off()

ax.add_collection3d(moon)
ax.add_collection3d(earthcopy)

#plt.show()

# 4. Animation ======================================================

def update_fig(frame):
    global earthcopy
    earthcopy.remove()
    earthcopy = copy.copy(earth)
    earthcopy.transform(scale=[1.2,1.2,1.2], translate=[.5,-.25,0],rotate=s3d.eulerRot(frame,0) )
    earthcopy.shade(contrast=1.7,direction=lightDirection)

    ax.add_collection3d(earthcopy)
    return

anim = FuncAnimation(fig, update_fig, frames, interval=interval, repeat=True)
anim.save('earth_moon.html',writer='html')

msg = "saved {} frames, values: [{:.3f} to {:.3f}] @ {} milliseconds/frane"
print(msg.format(numFrames,np.min(frames),np.max(frames),interval))