MG turrets on tanks: is this possible?

[Sa8Gecko]

I'm currently trying to develop a way to attach Mg turrets
to tanks, so that they can have actually two turrets.
Download from the link below what I've accomplished till now:
xoomer.virgilio.it/sa8gecko/M1A1_turret.rar
You can find the unit under 'West>Armored>M1A1 (M2 turret)'
First, the credits:
1) the tank is a BIS M1A1, the turret is partly mine and a BIS M2
2) I've taken inputs from the following people, of which I've
taken/modified scripts and ideas:
- Philcommando
- Master Chief
- Smodedribs
- Unnamed
- Col. Klink
- Hater_Kint
and probably many other I can't remember

known bugs and issues:
- if you are the commander of the tank, you can switch to
back seat, but this will send the m2 turret to hell... so
don't do this
- if the tank gets damaged and everyone disembarks,the
turret gets misplaced, but this can be solved cause I know
why
- probably this unit cannot pass over bridges and besetposed
over buildings: again, I know why and can correct this
- the turret bends and warps a little on steep gradients
can do little about that
- the turret shakes badly while moving on desert island,
not in Everon: I don't know why
- probably won't work properly in multiplayer as for now
the scripts are not MP compatibles and because of de-sync
- you can't be the gunner of the MG: you have to order
the MG gunner to disembark to enter the MG turret.

there are issues with shadows and other model related
things, but I won't solve these as they're beyond the
scope of the project.

I got to pump up a little (more than doubled...) the hitting
power of the mg bullet cause otherwise the machine gunner
won't engage Hinds.
The unit is effective in clearing enemy infantry and keeping
enemy choppers at bay, when operating without AA cover.

That said:
this is an open development project: take what you want,
modify it and SHARE. If you have some ideas to make it
work better, please SHARE. I will update this thread every
time I come up with a better solution, or for answering
requests of explanations. Of course, I hope you would do
the same: that's the spirit of the project.

[Greg147]

This is good

Shame you can't start in the gunner position.

Is there any way to start off without the gunner, so his postition is empty?

[Sa8Gecko]

Is there any way to start off without the gunner, so his postition is empty?

a) start with an empty tank
b) if you're group tank commander you can order the M2
gunner to disembark, then disembark and enter the M2
c) (untested) put 4 tank in a group, so that the MG position
should show up empty, as there's no place for the additional
gunners in the group

[Greg147]

Thanks, i'll try that now.

[greg147]

OK, they both work well. Now I just need a way to put it into a mission...

[Sa8Gecko]

OK, they both work well. Now I just need a way to put it into a mission...

You may wish to wait someone better than me finishes it or
develop it further. Infact the tank has some issues with the
model (some surfaces are lit by night) and the turret ring
could be made solid to the tank, so it would wobble a lot less. As now it's only a 'tech demonstrator'.
I'm waiting that someone picks this up and develops it. I'll be
glad to help and brief him/her.

[Greg147]

Well its the only one like it i've seen so far. However, there is a MOD (cant remeber the name), who are making a MG that the commander can use. They've made a video with it, but I can't remember where I saw it

[h-]

That mod would be Red Hammer Studios...

[greg147]

Yeah, thats the one. I saw in on ofp.gamezone.cz

[Sa8Gecko]

Update:

- if the tank gets damaged and everyone disembarks,the
turret gets misplaced,

this should happen no more. As a plus, if the abrams gets
destroyed, the turret gets destroyed (damaged so that it
is no more usable) too.
More, if the vehicle gets repaired (by the player, the AI won't
repair it if it can't move) the original crew is reassigned and
usually re-enter the vehicle.

Download it from the same link above.

[Sa8Gecko]

Update:

- probably this unit cannot pass over bridges and besetposed
over buildings: again, I know why and can correct this

Corrected, even if the turret will look extremely bad if the
bridge or the building over which it is setposed is not lying
on flat ground. This is a consequence of the 'keep height'
given in vertex properties. Alas, little can be done about that.
That is, if you cross the bridge of Nogova, the unit will look
crappy until you reach a point directly over water.

- the turret shakes badly while moving on desert island,
not in Everon: I don't know why

probably corrected, extensive tests should be done to
confirm this, but I lack the time to do them.

[greg147]

Keep it up man, your doing great

[Sa8Gecko]

I've noticed a bug happening when the carrier (that is the
abrams) gets destroyed by a very powerful hit that moves
the tank. The turret gets misplaced. Now it should have been
corrected, the turret stays with the destroyed tank, even if
you move the wreckage. That obviously means that the
script is never exited, cause it can't, otherwise the turret would
be misplaced. The script is anyway executed at a reduced
rate, not to clog the CPU, so if you move the wreckage it
takes a little time for the turret to return in place.

greg147:
thanks for the support.

[Sa8Gecko]

I'll try to explain how it works for the ones of you who didn't
de-pbo it.
The core is a simple attachment script, made by smokedribs
and which I modified extensively. Simply, it places the MG turret
on the turret's tank, so that the illusion is that the MG is really
part of the tank. Since the main tank's turret can rotate, placement
is not so simple as if you have the turret on the hull. Infact,
since the M2 turret is not positioned on the main turret's
rotation axis, its position changes everytime the main turret
rotates, even if the tank is stopped. Since I don't know of
a way to know the tank's turret rotation angle as respect
to the tank itself, I recurred to placing two cargo proxies in
the tank p3d model and made them solid with 'otocVez',
so that when the turret rotates, they rotate with it.
Then the initialization script fill these cargo spaces with
gamelogics, so that they'll return a consistent position,
and processing this position I can place the M2 turret perfectly
in its place. One gamelogic would be sufficient to place
the turret exactly, but I need two so I can have a direction.
Infact, since there's no way to know if the main turret rotates,
when this happens the M2 turret should rotate too, of
the same amount of degrees. This because otherwise,
even if the M2 turret would stay in the right place, it would
mantain the same direction , so that it would appear to
rotate even if infact it is still! With the other gamelogic,
instead, I can know the main turret's direction and so set
the M2 turret's direction accordingly. You can try this entering
an empty tank as the main gunner and rotating the turret
in third person view: you'll see the M2 turret mantains the
same direction as regard to the main turret. That is, if the
main turret is pointing 30 degrees and the M2 is pointing
350 deg (-10 deg), if you rotate the main turret to 180
degrees the M2 will follow this rotation and point at 140
degrees, while without the second gamelogic for direction
it would have still pointed to 350 degrees. So it would have
appeared to rotate, while it should have stayed still.
As a further precaution, I set the turret velocity to match
the tank's one itself, so that the 'shaking' that would be
clearly visible at low framerates should be reduced. This
is also useful for the script that ejects the spent cartridges,
since if the tank moves fast the effect would have seemed
a little odd. A drawback of gamelogics is that, if you are
tank commander, you can switch to the back seat of the
tank,which is occupied by them, and doing so you will cause
the M2 turret to be misplaced until you return at your seat.
Another issue is when the tank gets damaged so that
everyone disembarks. To correct this, the gamelogics are
'killed' if this happens, so that they don't disembark the
tank. If the tank gets repaired (by the player, since the
AI won't do that) the gamelogics are 'resurrected' so that
the AI itself won't enter they position.
The soft point of the whole project is, as you can imagine,
movement on non-flat surfaces. More the gradient, and
more the problems. To alleviate this, at least on small
gradient slopes, some parts of the M2 turret model have
the property 'keep height' set on vertex properties. This
property make so that the vertexes follow the surface
above which they're placed, that is they're no more placed
horizontal but follow the contours. The weapon itself is
not given this property cause otherwise it would be badly
warped on sloped terrain. This gives the illusion the M2
turret's ring and tripod's base is glued to the tank's turret
(somehow). A better solution maybe to effectively make
the ring part of the turret hull, while the M2 turret would
only have the tripod, weapon and hatch. If you can do
without the hatch, still better.
Regarding the geometry lod of the M2 turret, this should
be made so that it doesn't collide with the tank geo lod.
As for the fact the M2 is not the commander MG as it
should be, but it's manned by a fourth member, this is
due at this stage for simplicity.

[Sa8Gecko]

Update (small,really):
upon request I've added the possibility to start as the M2
gunner. You need to place the player or the character you
want as the M2 gunner in the editor, write in its init line
this moveinCargo (name of the tank) and
name the tank you want the gunner to be accordingly.
I.e: you have an M1A1 with M2 turret on the editor: name it
'tank' for simplicity. If you want to be the M2 gunner simply
place a soldier in the editor, set it as the player and write
in its init line: 'this moveInCargo tank'. This will automatically
place the player as the M2 gunner.
This way you can move in the M2 gunner position soldiers
with different skill setting than the standard one, or different
type of crew. The unassigned M2 gunner position of the
eventual other tanks will be populated by the script, so
no need to do the thing above for every tank if you just
want to test it as the M2 gunner of a group of three tanks,
for example. Note that the M2 gunner doesn't need to be
grouped with the tank crew. This way, if you choose a
different group for the M2 gunners than the tanks' crew one,
then you can group four tanks together, like BIS standard
tank group.