– Houdini 6.5.40 –

1 - create a null object

2 - create a path object

3 - assign/pick the path object to the null object

4 - keyframe the path/position parameter at frame 1, pos = 0
5 “” “” “”“ frame 150 , pos = 1

When I play the animation the null doesn't move smoothly along the path, it just jumps to the end of the path at frame 150. I tried adding a keyframe at frame 75 of pos = .5, but it also just jumps to that pos at that keyframe.

In the channel editor there is no ”curve' generated between the keyframes.

This behavior seems to be a result of whatever interpolation / transform function is built in to the null object.

How do I make the null follow the path ? Or should I just use a geo object ?

Is /was this a bug? I haven't tried it in ver 7 yet.

I was actually trying to get a non-kinematic bone (the pelvis of a character) to follow a path, and observed the “jumping” behavior.

It seems to work ok with a an IK bone, so I guess I can change the pelvis bone to an IK type if that is what will make it work.

Mike

I just tried it and it seems fine (6.5 not 7)
not sure why it's not working for you

i'm not infront of houdini at the moment but i know it should work because i've done it before. sometimes i'll animate a null along at a path so i can use it as a camera lookat point. This was pre 6.5 too..

Scope your keyframed channel in the channel editor. Box select all of it. At the bottom, change the function to cubic() or linear(). I suspect somehow you keyframed the channel as a constant() or something?

Edward,

Thanks !

That was exactly the problem, and just what I was looking for. I looked through the docs but couldn't find where/how the function curves are set.

Yes, “constant()” was showing in the parameter fields, but I couldn't figure out how it got there or how to change it


Mike

Yes, “constant()” was showing in the parameter fields, but I couldn't figure out how it got there or how to change it

next to that field, there is an arrow to bring a drop down menu of interpolation functions.