Path question

[markeh]

I am wondering how to make a camera's orientation follow the twisty curvy paths orientation like the one shown in the video, or more importantly, how to make a coaster car follow the orientation of the path. Making the camera or object follow the track is easy enough by making one of the pipes splines the path. Also, I was able to create two path constraints from the camera to the two outside rails which keeps it from moving into the mesh when the track twists and turns. I thought that would actually cause some weird circular constraint problem but it didn't. But I would like for the camera or for the coaster car to be oriented the same way as the track. In other words, if the track is upside down, then the camera or coaster car should be upside down on the track. Any ideas are much appreciated.

prob.mov

[Fishman]

I think the way to approach this is to add some key frames when the car makes the transition from horizontal to vertical. My son ran into this once (with another program) and we solved it by key framing the camera rotation such that it forced the orientation when it tried to flip. It has to do with the camera not being able not knowing what the top of the path is, so you have to show it.

 

Good luck,

Scott

[jamagica]

I'm sure there's a better way. Having to add keyframes to solve orientation problems, most of the time, means there's another solution. Maybe it has something to do with gimble lock.

[Fishman]

I looked in the help file under paths. They suggest two solutions. The first is to turn off Store Roll, otherwise it tries to keep the roll handle aimed upwards which creates the effect you are seeing. The second is to use an Aim Roll at Constraint and place a null at the center of the loop. That way the camera or car will stay on the track in the proper orientation. I think the two together will create the desired effect.

 

Hope this helps,

Scott

 

Scott

[Guest jandals]

Here's a project file that does what you need, I think.

 

There's one model in it that's supposed to be the rails. The model has a bone path-constrained to each rail. And another bone that positions the two Nulls, which handle the camera.

 

Pick it apart and ask questions if you've got 'em. The important things are that all the bones are in the model with the rails (paths) and to make sure you go through all the constraints in the pose.

 

Try toggling store roll first. See if that gets it.

 

Rhett

Coaster.prj.zip

[markeh]

Thankyou for all the replies. I'm still trying to get it to work right. The project makes perfect sense and I believe I have all the constraints right in both the pose and the choreography. It looks like now the camera is twirling around the z axis like it's yalling but it is also pointed in one direction throughout the whole path. I'm still working on a question but I will try this with a more simple model first and then bother with the questions.

[Guest jandals]

It looks like now the camera is twirling around the z axis like it's yalling but it is also pointed in one direction throughout the whole path.

 

By thunder you're right! I didn't catch that. It's pretty easy to fix,though (i've changed the bone names). I added a bone ("Roll Target") to the end of "Rail1" and then gave "Crossbar" an "Aim Roll At" constraint targeting "Roll Target." I also deleted an Orient Like constraint from Crossbar because it didn't do anything.

 

Anyway, the Aim Roll At constraint gets "Crossbar" to rotate with the track and the nulls and camera go with it.

 

I think you may be stuck keying the offset in the Aim Roll At constraint to get the camera to "look ahead" when the track turns. But at least it's only one channel to worry about...

 

Be aware that in the project I had to have a 90 degree roll offset in the Aim Roll At constraint. You'll probably want to adjust this offset so the camera aims at what you want. When you build the rig you could role the bone so you wouldn't need the offset.

Coaster.prj.zip

[Rodney]

The classic attack on this problem is to insert a Null at the center of the location where the object will turn upside down. Adding a 'Aim at' constraint then keeps the object oriented in relation to the null.

 

The old manual (available on the Hash Inc FTP - look for it in the 2002 directory) has a tutorial demonstrating this technique with a plane flying in a loop. Good stuff.

 

As Jandals demonstrates there are several attacks.

Adding a Null may be the easiest however.

[RoyBU]

Having just spent 15 minutes looking (unsuccessfully) for the plane loop tutorial in the 2002 manual, I just thought I'd point out that it is actually in the current technical reference: open Help/Help Topics from within AM, do a search on "loop" and look at the topic "About Aim Roll at Constraint Objects".

[Rodney]

Having just spent 15 minutes looking (unsuccessfully) for the plane loop tutorial in the 2002 manual, I just thought I'd point out that it is actually in the current technical reference: open Help/Help Topics from within AM, do a search on "loop" and look at the topic "About Aim Roll at Constraint Objects".

 

My apologies. I didn't mean to imply the tutorial was in the 2002 manual.

It's in the current Tech Ref but I believe goes into a bit more detail in the old manual.

 

I thought it was located in the 2002 folder on the FTP.

The current Technical Reference is a compilation of the old manual in web based searchable form.

The old manual is still available on the Hash Inc ftp.

 

Looks like it is here:

ftp://ftp.hash.com/pub/updates/windows/Am98/

 

or more directly here:

ftp://ftp.hash.com/pub/updates/windows/Am98/am98manual.pdf

 

For the completist out there the Tech Ref write up can be found here:

http://www.hash.com/htmlHelp/v12.0/Generat...ConstraintA.htm