Hello, The following works in Maxima 5.27.0.1 on Windows, and fails with Maxima 5.28 (nothing happens). load(draw)$ draw3d(xu_grid = 30, yv_grid = 60, surface_hide = true, parametric_surface(cos(phi) * sin(theta), sin(phi) * sin(theta), cos(theta), theta, 0, %pi, phi, 0, 2 * %pi))$