View Full Version : Semi and Trailer animation - need some help

04-16-2013, 03:24 PM
You would think this would be fairly easy but nooooooooooooooooo.

I have a motion path, a truck target following that, a semi truck parented to that target, and a trailer parented to the truck. The target's motion option for heading is motion path. So right now the target follows the path (yes!), the semi follows along turning just fine to follow the path (yes!!). The trailer duplicated the truck's heading - which unfortunately isn't correct (boo!). It needs to rotate about the back wheels so that when the truck makes a tight turn the trailer kind of lags behind. Well....that's not 100% true. The rotation point of the trailer is over the back wheels of the truck (which is what I have now) - but somehow the back wheels of the trailer somehow have to come into play somehow. Right now I'm hand animating the rotation of the trailer - but this is proving pretty damn challenging itself.

An example - if the truck is slowly turning 90 degrees over say 90 frames, the trailer itself would turn 90 degrees in way more than 90 frames as the truck turns much sharper than the trailer. Man...I hope that made sense.

So...I'm hoping there is some way to do this all without key framing and I'm also hoping some brilliant fellow will give me a clue.
Any help would be greatly appreciated.


04-17-2013, 06:19 AM
You could use Relativity module (in the motion options panel, Add Modifier) to set up a null that follows you truck motion by the distance of your trailer. Then have your trailer use that null as a target (motion options panel, Target Item).

04-17-2013, 02:27 PM
lertola - thanks for the idea. I did try it - but must have done something wrong. It didnt work quite the way I expected. That's cool - I ended up animating the trailer heading by hand. It didn't turn out perfect but close enough for as far away as the camera was to them. Thanks for your suggestion.