having a stand alone collision mesh would be optimal so you have control over what collides and what doesnt. using lod0 it collides with everything, and using lod1 it collides with places that would be open on the main lod and miss other points of detail like the antennae structures mentioned above which have been ommitted. even then you can cull a huge number of polygons from the collision mesh. surely your 12 sided cylender your using as an antennea can be a simple 4 sided shape in the collision mesh, a small structure like that after all wont show much error in where the collision happens neither would most shallow greebles reduced to less complicated shapes. curved surfaces can be reduced by large amounts too.
really all you need to do is take the diaspora concept, and make the engine consider that arrangement when doing collision tests. what exactly where the issues with the diaspora method? it looked good on paper, its sad that it didnt pan out as intended. figure out why that didnt work, what issues they had, call em bugs and fix them. way id set it up is add a submodel prop to define a model as an explicit collision model, and add another prop to reference that model in the subobject it represents.
collision meshes would be given a named reference (granted it can use the submodel name or number, ommitting everything to the right of the
$colision model: somename
and on objects that use collision meshes they would use the named reference
$use collision model: somename
it would be considered an error to attempt to use a collision model as a sybsystem or any other kind of model or to attempt to render it.
-or- you could do this
$collision use lod: 1
for people who think that lod1 is enough and use that
i would allow both, for convenience.
or you can just use the diaspora conventions, but they are kind of cryptic and collision detection was not their intended function (such as colide_this_only was intended for objects you did not want to be collideable at all, not for redirecting collision detection to another model).
