4. Rigging basic.
Now to set up the tank for C&C3. There are more than one way to do this, I will go over the basic method first. This method is recommended for very basic models.
Firstly, we must orientate and align our model. Make sure it is sat on the ground (unless your model hovers) and rotate it so it faces to the right in the Top viewport. Center your vehicle above absolute zero (where the two thick lines on the grid meet, aka the 'Origin') as best as you can.
Select the meshes for the turret and detach it from the main body. Name it Turret.
Select your turret and go to the hierarchy tab. Click the Affect Pivot Only button and Align to World. Now move the pivot point to the center of the turret's rotation. Test it by clicking the Affect Pivot Only button again (turning it off) and rotate the turret.
Select the meshes for the barrel and detach them, remember to include the parts that elevate with it (the mantlet for example). Name it Barrel.
Select the barrel and go to the heirarchy tab again. Click Affect Pivot Only and Align to World. Now move your pivot to the center of rotation (elevation) for the barrel. Click Affect Pivot Only again to test it.
What we have done here is positioned and correctly aligned the pivots for the turret and barrel that the game will use. The turret rotates on the Z (blue) axis and the barrel elevates on the Y (green) axis. The X (red) axis points to the front of the vehicle, and will be the direction of travel for warheads fired from the weapon.