Keyframing a trailer

[ddustin]

I need to slide a trailer out at a specific point in time.
How can I do that?

Is there a way to do it without deleting the existing frames and keying it manually?
Thanks,
David

[YMangolds]

Only thing I can think of would be to build a new rig ontop of, and bound to, your existing trailer rig. To get the most control I'd make a dummy object (in max) or a locator (in maya) then position and orient it to your existing TowingHookMeshTransform, then parent/link it so it's a child of your current TrailerBodyMeshTransform and inherits it's animation (and in theory would stay at the same location of the hook). Then create 2 extra wheels and have them match the scale and position (and possibly suspension settings) of the wheels of the existing trailer, and parent/link their ChassisSuspensionMeshTransform's under the new dummy/locator you made (and make sure their gravitymeshes share the same ground as your trailer). Attach your hirez mesh to this new system (main body to the dummy/locator and wheels to the appropriate extrawheels). Then manually animate the dummy/locator's rotation in Y (if you use Y as up) at the desired time you want it to skid. Then resimulate the extrawheels starting from the begining of the shot. Could also animate the dummy/locator in Z to get the trailer to tilt and play with the extrawheels settings to make 1 wheel come off the ground.

[Luigi Tramontana]

great solution (:
I'll see if it could be implemented directly into the trailer tool.

[ddustin]

We have tested YMangolds idea and it works well.
We added a 2nd trailer, linking it to one of the Extra wheels and it looks like it will work also.

Now we need to test it with our full set (tractor,2 trailers and the "dolly").

Thanks for the idea.

Sliding of trailers is something that happens a lot (at least in our industry).

David

[ddustin]

We ran into a problem using this approach.

When we added the extra wheels to the project, initially it was OK.
But after saving the project file then reopening and resimulating, there is now a lag in the extra wheels.
The project file is here http://www.dustinproductions.com/wip/cr ... ting02.zip
Open the file and resimulate it and you will see what I mean (unless there is something stange with my installation), the extra wheels now lag behind the trailer wheels.

We are using max 2009, XP64.
There is nothing I can find other than closing the file and reopening it.
Adding a wheel to the 4wext does not produce the same results.
Thanks for any help.

David

[ddustin]

The problem issue seems to be a lag in the constraint of the extra wheels to the the added dummy.
The lag is almost exactly 1 frame.
We added another dummy to the one by the hitch and parented the extra wheel chassis to it, then that dummy was linked/parented to the dummy at the hitchpoint.

We wrote a very simple script to offset the distance of the dummy everything was linked too by one frame.
The was not exact, but very close.
It is strange that this issue onlt\y cam up after closing and reopening the file.

David

[Luigi Tramontana]

Hi Dustin.

This problem has to do with simulation order of parented objects. We are discussing on a general methodology to automatically detect the simulation order without the user having to tell the system which order he would like, however it might turn out that this is an impossible problem because sometimes there are nodes that are parented in a loop inbetween tools.

However, a solution to your current problem is to rearrange the order in the tools-tree. By drag and dropping the extraWheels on to the Trailer you tell the system to first simulate the trailer, then the extraWheels which will yield the result you are after.