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Driven Object


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Ok so I've been monkeying around in the hdk again and built an object version of "set driven key" to give it it's maya name.

This is one of those things you can do in chops or expressions but it's a bit obscure, so I thought I'd have a go at turning it into a proper object. Actually it's a null object really. Anyway it's kinda in beta if you want to play with it. Compiled for windows H8.0.354 and with source - hopefully it's all there, I doubt it though since I usually forget something.

One thing I'm still wondering about is whether to try and make it store the keys and transforms in the hip file, at the moment it rebuilds an array for each cook and then searches it for the correct pair of keys to use, with a lot of keys or a lot of instances of the object this would get very slow but for the moment it works at least.

Until I write some help here's how to use it.

If you look in the attached hip file you'll see an example set up.

Basically you parent it to your driver object and then use a null that is also parented to the driver object to set key positions. The channel called "Driver val" should reference a channel that does the driving and would probably be an animated channel from your parent object, or as in the example it directly references a chop that animates a set of bones.

Simply animate the parent object then at values where you want to create a new key position move the null object where you would like the driven object to be and hit one of the "Get key" buttons to snap shot the values. The final position of the driven object is then interpolated from these keys depending on the driver val at the current frame.

The only thing to be careful of is that the key positions you choose should be in some sort of logical order, notice in the example how the driver key values increase from 29 for key 0 to 107 for key 1 to 135 for key 2.

It sounds confusing when written down, hopefully the example makes it clear.

DrivenObject.zip

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A few bug fixes and help file added. Recompiled for H8.0.383

DrivenObject.zip

Anyone know the proper way to get a callback to work on a multiparm parameter when it is deleted? At the moment I've stuck the call in the disableParms call since it seems to be the only thing that gets called when a parameter is deleted and multiparms themselves don't allow for a callback.

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