def METHOD_NAME(n_horizontal, n_segments):
    """ Helper function: Vertices of the UV sphere primitive"""
    vertices = [(0.0, 0.0, 1.0)]
    for theta in (np.pi/n_horizontal)*np.arange(0.5, n_horizontal):
        for phi in (2*np.pi/n_segments)*np.arange(n_segments):
            sin_theta = np.sin(theta)
            x = sin_theta * np.cos(phi)
            y = sin_theta * np.sin(phi)
            z = np.cos(theta)
            vertices.append((x,y,z))
    vertices.append((0.0, 0.0, -1.0))
    return vertices