Just discovered why rocks can't be collisionable in game, even with the static.object controller attached to them. If you open any terrain object you will see that this class of SH5 objects got, depending on their size and shape, one or more collision meshes. Basically some simple boxes. Missing them, rocks can't be collisionable.
Unfortunately, adding new meshes with GR2 Editor is not possible at its current state. The one chance would be "rebuilding" undersea.GR2 with the same meshes, textures, bones, etc. as the original file, but using as templete a GR2 file with 1 model and at least 9 meshes; i.e. 3 meshes for the 3 "grass" types, which are not supposed to be collisionable, and 6 meshes for the 3 rock types, 2 for each rock, one for the visible rock, and one for use as its collision mesh. Anyway SH5 rocks are placed randomly, and they change position everytime you turn the camera. They are designed more for eye candy than else, and I am not even sure that my idea would work. Maybe it would be better leaving undersea.GR2 alone, and creating some brand-new rock objects, for use as collisionable terrain objects to be placed ad hoc the same way blockships are placed around scapa.
On a side note: I have noticed that ports completely miss reflect meshes. Can someone confirm that ports' buildings, docks, etc. have reflections on the sea surface?
EDIT: okay, nevermind, just checked and they do have reflections.
