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View Full Version : Keeping objects on the outside of a path



wacom
06-07-2003, 10:58 AM
I'm having trouble keeping an object oriented on the "outside" of a path. It seems that once it crosses the paths Y axis it "flips" around suddenly. The heading of the object goes from 0 deg to -180 and so it "swings around". Any suggestions or help would be great. Oh and my path is a lot more irregular than the bad image I made as an example of my problem. Thanks a million and one.

Mylenium
06-07-2003, 12:24 PM
Well, there is no simple solution 'cos this is caused by a mathematical phenomenon. The easiest solution would be an Null object that orbits in sync with your other object but on a larger radius. You then could target your object to this Null.

Mylenium

wacom
06-07-2003, 01:11 PM
Originally posted by Mylenium
Well, there is no simple solution 'cos this is caused by a mathematical phenomenon. The easiest solution would be an Null object that orbits in sync with your other object but on a larger radius. You then could target your object to this Null.

Mylenium


I've tried this- and it works to some degree but I still get some strange moments of "flipping around". Is this the only way? Is there a way to put constraints on the object? It seems that once it's on the path and following it IK constraints don't work or are over ridden by the path. I'd convert the motion to keys and then manualy over ride them, but I have to do this for up to 50 objects on diffrent pathways. Thanks for the suggeston Mylenium...I'll play around with the null on a larger path solution some more 'til someone else comes up with something or I figure it out. Thank you though.

Danner
06-08-2003, 05:31 AM
could you get away without using align to path, and doing the rotations with a couple of keyframes?

wacom
06-08-2003, 11:35 AM
I could just key fram all of this, or just use expressions, but the path shown above was just to simply illustrate my problem. My actual path (shown down yon'dar) going around this sphere is too complicated for key frames. I'm going to need at least 5 unique pathways duplicated about 30-50 times. Call me lazy but...

toby
06-08-2003, 03:34 PM
align to path has definite limitations. If you haven't noticed, when an object hits the end of it's path it flips backwards. I once had to dissolve out the object with align to path on it, and disslove in one without it.

With align to path on, set keyframes, then use the graph editor to fix the rotation values

riki
06-08-2003, 06:50 PM
You could try this. Make a null follow a path, position your object next to the Null, on the outside of the path. parent in Place to the Null, and then rotate your Null slightly at each keyframe.

Here's an example, maybe not the best way to do it but seems to work.

http://www.suture.net/files/0022.zip

wacom
06-09-2003, 08:56 PM
Originally posted by toby
align to path has definite limitations. If you haven't noticed, when an object hits the end of it's path it flips backwards. I once had to dissolve out the object with align to path on it, and disslove in one without it.

With align to path on, set keyframes, then use the graph editor to fix the rotation values


Ah-ha! That sounds great! I'll run it through with key frames- then I'll use an expression to limit the heading and/or pitch! Thanks- I'll give it a try and tell you how it works.