Driven OBJ

Overview

The Driven Object serves as a place-holder in a scene, and does not render. It's position relative to it's parent is driven by a channel reference to another objects animation, typically this would be a rotation channel from the parent object.
The driver channel is used as the input to a lookup table of "key" positions specified by the multi-parm transform channels.

You can set key positions either manually or by using an object wired to input 2. When using the second input you can grab the transforms and driver key values using the Get key # button. The Put key #  button allows you to return key transforms to the object wired to input 2 for tweaking purposes.

Parameters

Misc tab

All the parameters from the Render and Misc tabs of a normal Null OBJ, see the Null OBJ help for details

Driven tab

Interp Type
When the driver value falls between two key positions the interpolation type determines how the intermediate rotation values are calculated.
Euler treats rx,ry,rz as independent channels and interpolates each one individually.
Quaternion combines all three rotates into a quaternion vector and interpolates by shortest path.
      
Driver Val
Animated channel to use as a lookup value. - usually a reference to another object or chop
Example Imagine the Driver val varies between 50 and 150, and Driver key 0 = 50, Driver key 1 = 100, and Driver key 2 = 150, if on frame 1 Driver val is 75 then the Driven object will be located half way between the position at Driver key 0 and Driver key 1.

Driver Key
When the Driver val hits this value the Driven object will be transformed by the values stored in the transform parameters for that key. If the Driver val is between keys the position will be interpolated.

Interp Type Euler or Quaternion interpolation of rotation values
Ease Ease the interpolation
Driver Val Animated driving channel
Driver Key 0 Initial key value
Get Key 0 Grab the transforms from object wired to input 2, and the key value from driver val
Transform Order Order of transformations
Rotate Order Order of rotations
Translate Translation along xyz axes
Rotation Degrees rotation about xyz axes
Scale Non-uniform scaling about xyz axes
Pivot Local origin of the object
Uniform Scale Uniform scaling about xyz axes
Reset Transform Reset transforms to defaults
Put Key 0 Copy the transforms back to the object wired to input 2
Number of key positions This controls the number of key positions that will be used
Enable key Determines if this key will be used. Disabling a key this way can be useful if you don't wish to recreate it.
Driver Key # Key value for # key
Transforms All the transform parameters as for key 0
Reset Transform Reset transforms for # key back to defaults
Put Key # Copy the transforms for # key back to the object wired to input 2