null (or no kinematic bone) on a path - no channel curve

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– 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
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I just tried it and it seems fine (6.5 not 7)
not sure why it's not working for you
Michael Goldfarb | www.odforce.net
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SideFX
www.sidefx.com
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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..
Dave Quirus
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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?
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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
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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.
Dave Quirus
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