I have a key shape of SUSPENSION going from fully squashed to fully stretched.

The range of the key shape

The key shape is for the suspension of this vehicle rig.

The rig

The key shape is 100% weighted to an IK bone.

I've also created two small cubes that are weighted to the bones directly above and below the key shape (the varying distance between these two cubes will be used by the driver).

Two cubes to create a distance relationship

The maximum distance the cubes will be apart is ¬2.6 blender units. (Blunits?) The minimum distance is ¬0.7 blunits.

I put a driver on the Shape Key value, and set this to Sum Values, then selected the two small cubes to provide the distance.

Driver details

I've moved one of the cubes closer & farther from each other and the driver works! The key shape of the suspension changes.

Now I need to adjust the range of this distance driver so that it matches to where the min + max values need to be in relation to the rig.

...but I don't know how. Any help would be greatly appreciated. Thanks!

The desired outcome


1 Answer 1


You need to setup Driver's F-curve. It shows how distance between objects (horizontal) corresponds to Shape Key value (Vertical):

enter image description here

So if distance 0.7 corresponds to Shape Key value of 0 and 2.6 corresponds to 1, You need to create a line between this 2 dots in drivers window:

enter image description here

  • 1
    $\begingroup$ 1: Crantisz, this worked! Thank you. :) 2: How I actually solved this was when I discovered that the driver would work when I manually moved the two cubes apart (G + mouse move the cube thereby making the driver respond), however the driver DID NOT RESPOND when I moved the cubes apart via the bones in pose mode (giving me false results). This is because I weight painted the cube in place instead of parenting the cube to the appropriate bone. When I removed the weight painting, then parented the cubes to their bones I could then adjust the driver's F-curves and get proper results. $\endgroup$
    – Mat Brady
    Mar 29, 2018 at 22:11
  • $\begingroup$ I finally understand the Driver Editor thanks to your answer and infoGRAPHic (punintended). $\endgroup$ Jul 15, 2020 at 21:54

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