def METHOD_NAME(ad, species, color_vec):
    xp = ad[species,'particle_position_x'].v
    yp = ad[species,'particle_position_y'].v
    zp = ad[species,'particle_position_z'].v
    if species == 'plasma_e':
        selection = np.abs(xp)<2.e-6
        zp = zp[selection]
        yp = yp[selection]
        xp = xp[selection]
    vertices = np.column_stack((xp,yp,zp))
    colors = np.tile(color_vec,(vertices.shape[0], 1))
    points = yt.visualization.volume_rendering.render_source.PointSource(vertices, colors=colors, radii=1)
    return points