Animating a mayavi points3d plot

Question

I'm trying to make a video of the trajectories of particles. However, somehow my scene never updates. Here's a very simple example:

from __future__ import absolute_import, division, print_function
from mayavi import mlab
import numpy as np
import math

alpha = np.linspace(0, 2*math.pi, 100)  

xs = np.cos(alpha)
ys = np.sin(alpha)
zs = np.zeros_like(xs)

mlab.points3d(0,0,0)
plt = mlab.points3d(xs[:1], ys[:1], zs[:1])

@mlab.animate(delay=100)
def anim():
    f = mlab.gcf()
    while True:
        for (x, y, z) in zip(xs, ys, zs):
            print('Updating scene...')
            plt.mlab_source.x[0] = x
            plt.mlab_source.y[0] = y
            plt.mlab_source.z[0] = z
            f.scene.render()
            yield


anim()
mlab.show()

If I run this script, it shows a window with the two points and the animation GUI. It also prints a continous stream of "Updating Scene..." messages on the terminal. However, the scene doesn't show any movement at all.

What am I doing wrong?

Python 2.7, Mayavi 4.1, VTK 5.8

Answer 1

Just change to:

...

    for (x, y, z) in zip(xs, ys, zs):
        print('Updating scene...')
        plt.mlab_source.set(x=x, y=y, z=z)
        yield

...

you don't even need the f.scene.render(), according to documentation mlab_source.set guarantees the refresh.

Also since shape of your data doesn't change you don't need to use mlab_source.reset.

I also tested and works fine.

Answer 2

Have you tried mlab_source.reset? It works even when the length of the x, y, and z arrays are changed.

In your case, it'll be: plt.mlab_source.reset(x=x,y=y,z=z).