View Full Version : Obtaining consistent speed for item orbiting on an elliptical path

06-26-2012, 09:36 PM

I've been scratching my head on this.

I have an elliptical path generated by a null offset a distance from another to which it is parented. The parent null is rotating, as well as moving along the x axis by an amount calculated with some simple trig - resulting in an elliptical path for the child null.

Problem is - as it is at the moment the parent null rotates at a constant speed and results in a varying speed of the child null.

I realise that if I hand draw a (perfect!) motion path rather than use a parent null that I could use DP Motion Info to get it to traverse the path at a constant speed. However, I wish to retain the flexibility of adjusting the sizes of the orbit.

Open to ideas!

06-26-2012, 09:46 PM
Since it's just nulls, can you post the file so we can get a look at it.

06-26-2012, 11:24 PM


06-27-2012, 03:38 AM
Nope... you can still use DP motion info... It'll read the overall motion of a given item in world space, not just its parent space.

06-27-2012, 06:50 AM
An elliptical path would not have a constant speed.

06-27-2012, 08:13 AM
well, I guess any path with any shape, you can have a constant speed...it's just a distance like any other. Now, if you are rotating a parent null you will not be able to get a constant speed in the child null. Unless you modulate the parent's rotation with a function to change the rotation speed in order to get a constant speed in the child's translation. I may be wrong.

06-27-2012, 08:18 AM
An elliptical path would not have a constant speed.
Not (easily) done by parenting, no.

But obviously you could have an elliptical path and drive along it at a constant speed.

06-27-2012, 01:59 PM
See this thread http://forums.newtek.com/showthread.php?t=102423

Hope that helps.


06-27-2012, 11:58 PM
Those are some great solutions. Thanks everyone!