Python mayavi: Adding points to a 3d scatter plot

Python mayavi: Adding points to a 3d scatter plot

I'm writing a python application to simulate the motion of particles in
3-space. I'd like to plot the positions for each step, updating the plot
as the app runs, keeping the past positions on the plot.
I'd like to do this with mayavi, but as far as I can tell, one cannot
simply add points to an existing scatter plot, but must add all points in
one go. This is not what I want. I want to add a few points at a time
without having to keep all past points in memory to redraw them all at
each step.
The function I've been looking at is plot3d().
http://docs.enthought.com/mayavi/mayavi/auto/mlab_helper_functions.html#mayavi.mlab.points3d
Any ideas on how to do what I want with python mayavi? Is there another
python 3d plotting package that would do what I want?