The opacity setting seems to have no effect. Fuzzy shells cannot be merged. Crashes when image size differences are too great to display simultaneously. Specular and diffuse reflection seems to be the same when the parameters are set the same. This is okay when incident light direction is the same as viewing direction, but otherwise they should be functions of different angles.
Output destroys any existing file of the same name without warning.
Sometimes it is too big for the subwindow and crashes.