aerocooper aerocooper - 4 months ago 22
Python Question

How to animate a BuiltinSurface in Mayavi mlab?

I'm attempting to animate the Earth rotating using Mayavi mlab. I've succeeded in the past by just rotating the camera around a BuiltinSurface representation of the Earth, but this becomes inconvenient when I need to plot many other objects (spacecraft, stars, etc) in the frame as well. The code below seems to "almost" work: on my Windows 10 machine, it runs for 8 iterations and then the animation freezes. How can I fix this code, or is there a better way to animate a BuiltinSurface in general?

import numpy as np
from mayavi import mlab
from mayavi.sources.builtin_surface import BuiltinSurface
from mayavi.modules.surface import Surface
from mayavi.filters.transform_data import TransformData


def rotMat3D(axis, angle, tol=1e-12):
"""Return the rotation matrix for 3D rotation by angle `angle` degrees about an
arbitrary axis `axis`.
"""
t = np.radians(angle)
x, y, z = axis
R = (np.cos(t))*np.eye(3) +\
(1-np.cos(t))*np.matrix(((x**2,x*y,x*z),(x*y,y**2,y*z),(z*x,z*y,z**2))) + \
np.sin(t)*np.matrix(((0,-z,y),(z,0,-x),(-y,x,0)))
R[np.abs(R)<tol]=0.0
return R



@mlab.show
@mlab.animate(delay=200)
def anim():

fig = mlab.figure()

engine = mlab.get_engine()

# Add a cylinder builtin source
cylinder_src = BuiltinSurface()
engine.add_source(cylinder_src)
cylinder_src.source = 'earth'
# Add transformation filter to rotate cylinder about an axis
transform_data_filter = TransformData()
engine.add_filter(transform_data_filter, cylinder_src)
Rt = np.eye(4)
Rt[0:3,0:3] = rotMat3D((0,0,1), 0) # in homogeneous coordinates
Rtl = list(Rt.flatten()) # transform the rotation matrix into a list

transform_data_filter.transform.matrix.__setstate__({'elements': Rtl})
transform_data_filter.widget.set_transform(transform_data_filter.transform)
transform_data_filter.filter.update()
transform_data_filter.widget.enabled = False # disable the rotation control further.

# Add surface module to the cylinder source
cyl_surface = Surface()
engine.add_filter(cyl_surface, transform_data_filter)
#add color property
#cyl_surface.actor.property.color = (1.0, 0.0, 0.0)

ind=1
while ind<90:
print ind
Rt[0:3,0:3] = rotMat3D((0,0,1), ind) # in homogeneous coordinates
Rtl = list(Rt.flatten()) # transform the rotation matrix into a list

transform_data_filter.transform.matrix.__setstate__({'elements': Rtl})
transform_data_filter.widget.set_transform(transform_data_filter.transform)
transform_data_filter.filter.update()
transform_data_filter.widget.enabled = False # disable the rotation control further.

# Add surface module to the cylinder source
cyl_surface = Surface()
engine.add_filter(cyl_surface, transform_data_filter)
# add color property
#cyl_surface.actor.property.color = (1.0, 0.0, 0.0)

yield
ind+=1


anim()

Answer

I haven't been able to figure out a way to use Mayavi to make this happen. However, Vpython appears to be much better suited to accomplish this task. I've posted an example section of code below to make a revolving Earth, along with a few other features.

from visual import *

def destroy():
    for obj in scene.objects:
        obj.visible = False
        del obj

R = 6378. # radius of sphere
angle=0.
scene.range = 10000.
SunDirection=vector(.77,.77,0)
# scene.fov = 0.5
scene.center = (0,0,0)
scene.forward = (-1,0,-1)
scene.up = (0,0,1)
scene.lights=[distant_light(direction=SunDirection, color=color.gray(0.8)),
              distant_light(direction=-SunDirection, color=color.gray(0.3))]
x=0
y=0

while True:
    rate(10)

    angle=angle+1.*pi/180.

    destroy()
    s = sphere(pos=(x,y,0), radius=R, material=materials.BlueMarble)
    s.rotate(angle=90.*pi/180.,axis=(1,0,0)) # Always include this to rotate Earth into correct ECI x y z frame
    s.rotate(angle=90.*pi/180.,axis=(0,0,1)) # Always include this to rotate Earth into correct ECI x y z frame
    s.rotate(angle=angle, axis=(0,0,1)) # This rotation causes Earth to spin on its axis

    xaxis = arrow(pos=(0,0,0),  axis=vector(1,0,0)*7000, shaftwidth=100, color=color.red)
    yaxis = arrow(pos=(0,0,0),  axis=vector(0,1,0)*7000, shaftwidth=100, color=color.green)
    zaxis = arrow(pos=(0,0,0),  axis=vector(0,0,1)*7000, shaftwidth=100, color=color.blue)

    ST = cone(pos=(0,8000,0),axis=(0,700,0),radius=700*tan(10*pi/180),color=color.blue,opacity=1)
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