View Full Version : Path Constraint rigging

04 April 2011, 06:17 PM
Hello all, I'm using Max 2011 and I've come across a tricky rigging challenge here at work. I have a system of video panels that need to run along an oval track, the panels should move at the same rate and need to follow the oval path of the track. My initial though was that I could use a path constraint to run them along the track and a look at constraint to keep the wheel aligned with the track, which worked fine, but I'd have to manually key each panel and it's look at object. I wanted to avoid that tedium and just animate one object and have the rest follow the way they're supposed to.

I tried looking for tutorials on how to rig a roller coaster or a train but couldn't find anything for Max, but I know there's gotta be a way. Does anyone out there have any recommendations on how to handle a situation like this? Is Reaction Manager my best bet here? I could write a float expression on the percentage of the path constraint but I have limited experience with writing expressions so I'm not sure where to start with that one.



04 April 2011, 11:03 PM
If I get you right, you are trying to have your object aligned to the shape as it travels on it, right?
Then all you need to do is check "Follow" in your Path Constraint parameters.

But since I do not feel comfortable with this level of control, i like better to:
1-Make a dummy that runs on the same shape a little bit further, preceding your object
2-Make your object look at it.
To achieve your dummy running this way, it must use a path constraint as well, with the "% along path parameter" wired to the same parameter of the path constraint of the original object, by some expresion like this:
So your dummy is always 1% of the path ahead, leading your original object...

But in your case, the "Follow" alternative should be fine, I guess.

04 April 2011, 04:46 PM
The follow thing worked great but every time I tried to wire the percentage from one to another it would snap the child's location to the master. I tried Percent-1 and it still moved the child. Any ideas?

04 April 2011, 03:19 PM
Oh, I figured it out. It's a percentage so if I wanted it to follow 10% behind the control object I put "Percent - 0.1", Not "Percent - 1" Like I was trying. Thanks for the help.


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04 April 2011, 03:19 PM
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