Any ideas/hints on make these Blast Bags (selected object in the screenshot) move with the barrel, but also keep them siting in the turret, so that the front part keeps tight around the barrel and the other part stays within the turret?

Is there a way except animating it by hand?

Iowa Turret

The thing I want to achieve is, that those Blast Bags (they are usually made of fabric) behave as if the one end of them (line A) is fixed inside the turret and the other end (line B) sits around the barrel.

Iowa Turret 2

When the barrel now moves up and down in the turret, the lines should still stay fixed to the barrel/turret to get an effect like this (This is sloppy made for demonstration):

Iowa Turret 3


1 Answer 1


Given the restricted range of movement required, a physics/cloth simulation might be a bit over the top? Maybe a 2-bone armature will do.. The joint between the bones is at the center of rotation of the barrel.

The root bone could be a child of the turret, the barrel-bone constrained to point down the barrel. You could start with automatic weights, and tweak in weight-painting to something like this:

  • Barrel Bone

enter image description here

  • Root Bone

enter image description here

If you want to introduce folds in the fabric, you can use corrective shape-keys. There is one in this animation, but only to suppress unnatural bulging...

If you haven't rigged to an armature before, I wish I could give a complete description in one BSE answer, but it would be too broad. Maybe check out some basic tutorials (not bothering about Inverse Kinematics to begin with), and if you get stuck on a particular step, call back with another question. This isn't a bad starting exercise.

enter image description here

  • $\begingroup$ Will definitely try that one out, thank you! $\endgroup$
    – D34TH11
    Commented Jul 28, 2019 at 22:09

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