Applying rigidbody forces to different parts of the same body?

So i just watched this video by the Yogscast (hilarious, by the way) where they mess around in Garry’s Mod and construct their own space ships.

One thing that sparked my curiousity was how the Hoverballs in that video affects the rigidbodies they are attached to, and I started thinking how I would implement that in Unity.

As seen in the video, a Hoverball provides an up force of some description. However, to make a large body hover with a level heading, one needs to place these balls somewhat symmectrically along the bottom side of the body. If you just place two hoverballs where the front wheels of a car would be, it would just start spinning, since the force seems to be applied locally in object space. Is it possible with Unity rigidbodies to do something like this? As far as I remember (Cant launch Unity on this machine), applying a force to a rigidbody sort of applies it to the center of the object (im guessing at the transform), and therefore wouldnt start rotating the body if the ball was placed off-center. It would just push the entire body up wards. And Im assuming make the body hover, if the force was equivalent to the gravity in Physics settings.

Making a Garry’s mod clone seems like a massive undertaking, but this particular point sparked my interest. Physics is always fun - some times…

I haven’t played around with physics much in quite a while, but…

In the documentation, there’s Rigidbody.AddForceAtPosition(…) which appears to do exactly what you’re talking about.

Additionally, I’m pretty sure that if you make a child GameObject and apply forces to that through any means, it will apply force to any parent objects from its position, not from the parents’ positions (which wouldn’t make sense anyway). This was definitely the case when I used wheel colliders to make a buggy - if I applied force from just one wheel the buggy would spin, and so on.

Ahh… ApplyForceAtPosition seems to be what I’m looking for. I never knew that function was there, strange… However that last bit in the docs seems a little worrying. If applying force too far away from the object center, the torque becomes unrealistically large. I wonder what “too far” means in this context

Thanks for the input!