About This File
Some notes and technical information:
How to load a PHYS file in-game
Change your model globalflags to 32 (or 160 if your model casts shadows as well):
The bones with physics must have flag 1024:
Bones with physics will take their position coordinates from the phys file and ignore the position given in the m2.
Position is set in the WELJ, SHOJ or SPHJ chunks.
Bones with physics will not be affected by the rotation, scaling and translation of the parent bones unless they are added as an attachment.
As you can see in the image above, the gourds with physics are not affected by the m2 animation and will only move if their coordinate in the world changes.
This is why Blizzard makes separate m2 files for parts with physics. Exampe:
creature/fishmount/fishmount.m2 (base model without physics)
creature/fishmount/fishmount_wiskersleft.m2 (left wisker with physics)
creature/fishmount/fishmount_wiskersright.m2 (right wisker with physics)
The wiskers from the fish mount are in different m2 files, attached server-side as a vehicle accessory. You can also add them as spells or items. If the whiskers were part of the base model, they will just be floating next to the head, since they would not be affected by the parent bone movement.
It's not necessary to separate meshes with physics if your model is static (i.e. helmets, weapons, shoulder pads, etc.).
However you can add physics to a bone, and animate all the bones connected to it.
(Since 7.1 models with physics don't have to be separated - See http://www.wowhead.com/item=143829 as an example)
Difference between MoP and WoD
The Phys file structure is the same for MoP and WoD.
However, the only thing I noticed is that in MoP physics are more sensitive and the shapes feel lighter.