Animate a single point on a spline with a null

[Gabe Gonzales]

I need a single point on a linear spline to animate along another circular spline while the other points on the linear spline are stationary. The linear spline only has two points, one on each end. How can this be done?

Thanks!

SinglePointAnimation1.c4d

[Dr. Sassi]

Hi Gabe Gonzales,

Thanks for the file.

I have included two options on how to do it.

CV4_2025_drs_24_ANsp_01.c4d

One works with XPresso and User Data
https://help.maxon.net/c4d/2025/en-us/Default.htm#html/5826.html

The other one uses two Nulls that generate a two-point spline by connecting these.
Then the Align to Spline Tag moves one Null around the Circle.

Let me know if you have any questions about it.

Enjoy your weekend

[Gabe Gonzales]

These work very well! Thanks for shedding light on two different ways to accomplish this.
A couple questions about the XPresso and User Data method: why did you create the Null_User-Data node to control the movement of the point along the circle spline when the spline node itself has an offset parameter that controls this movement in the same way (I imagine there is some benefit)? Further, it seems like the offset parameter in the Null Node and the Spline Operator will only allow a movement of 0%-100%. Is there a way to expand this to allow for an animation that traverses the spline many times?

[Dr. Sassi]

Hi Gabe Gonzales,

The User Data option is for convenience. Otherwise, you must open the XPresso Editor before your animation setup session and search for the right node. Doing that in a project after a month is not fun, and things get complex occasionally. The idea is always to work towards a setup that is not in the way of animating the scene. When one is in the flow, things must be simple to handle and able to focus on what is important, and that is never to search for a parameter somewhere.

Those User Data Entryries can be done all on one Object (or several), allowing for the creation of a mixer panel. From there, creating a HUD (Head Up Display) Copy in the editor window is also easier. Which can show up when the Object is active or permanent. Like in a car where no one would put the head-light switch into the trunk

The Spline node is limited in this regard. If you like to have more, you can do it via Math. Example:
CV4_2025_drs_24_XPsp_01.c4d

Or just use a Helix and set the Height to zero, then increase the End Angle and perhaps the Interpolation. It looks like a circle, but it is so much more.

Cheers