Advanced Model Exporting
NOTE: This is not a guide for learning basic Blender or
Quake .MDL
exporting concepts.
Introduction
Nazi Zombies: Portable uses the standard Quake
.MDL
format for most of its props and other meshes.
Specific to view models, however, it utilizes a special fork of the
common io_mesh_qfmdl
Blender export plugin, adapted to better support Blender
2.9X
and contain features to mitigate vertex swimming.
That forked export plugin can be found here.

Features
“First Frame” & “Last Frame”

Contrary to the vanilla
export plugin’s usage of the playhead on the Blender timeline for frame
selection, NZ:P’s fork utilizes Properties
menu entries for
determining the start and ending frames to be baked into the resulting
.MDL
. This is particularly useful for wanting to export
precise chunks of animation data.
View Model “Bounding Box”

The MDL Mins
and MDL Maxs
properties define
a minimum and maximum region for vertices to cross over. The intended
benefit of this is to only warp/swim vertices to their max point of
camera visibility in order to preserve fine details such as weapon iron
sights. Enabling Show MDL bounding box
will give you a
visual representation of this box to use as reference.

It is important to consider that bounding boxes need determined based on expected view model field of view. It is recommended to set up a Blender camera with the intended field of view and set it as active to get a live preview of how well your bounding box accomodates every frame you are intending to export.
