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View Full Version : Align to path problem



bjornnilsson
03-31-2009, 12:40 AM
Hi all,

I'm working on animation with a car that turns around a corner, then
stops and waiting for a gate to open,
and then driving through when it's open.

When the car is still and not moving forward, it flips around without
any keys for a heading rotation. What am I doing wrong here?

Thanks
Bjorn

hdace
03-31-2009, 12:29 PM
Awhile back that happened to me too. Have you got align to path applied to pitch or bank? You may be hitting a gimbal lock situation. As the motion options "look-ahead" settings see the car pulling out it might hit gimbal lock on an axis which will force another axis to suddenly move, usually by more than 180 degrees.

The way to fix it is to play with the look-ahead settings and also maybe align to a null with an envelope during critical moments and then "un-envelope" a given axis once the car is moving again (you know, the new "rotation item" section in motion options).

F_GX
04-01-2009, 12:18 PM
Good point, but i can hardly believe that gimble lock can occur with a car animation?

here's a good vid that explains the problem http://www.youtube.com/watch?v=zc8b2Jo7mno

I rather suspect that you're using Align to Velocity, and then when the car stops it will indeed flip. I couldn't make out any reason why that should happen with Align to Path.