IPO Driver Influence?

I have had a new universe opened to me (thanks Mike!) in IPO Drivers. What I would like to know is whether the amount of impact a driver has on another IPO can be altered, in the same fashion as the Influence slider in just about every constraint? If so, IPO drivers will be an incredible tool for my work…

Yes and No
There is no influence slider when applying an IPO driver. But you can set a IPO curve to run from 0.0,0.0 to “1.0,0.5” instead of “1.0,1.0”. Hence reducing the effect of the IPO driver.

Short Answer: Your IPO curve is your influence curve which your driver drives along.

Come again?? :o

If you adjust the “slope” of the IPO curve that is created when the IPO driver is created, you can adjust the sensitivity of the driver object, steeper = more sensitive (greater change in driven property per movement of driver … shallower = opposite)

Make sense ?


The words make perfect sense, but I am unable to find the slope you are refering to. Is this slope created at the same time the IPO driver is created, or are you refering to the IPO curve that is created once animation keys are built? When I create the IPO driver, no slope appears anywhere (as far as I can see).

EDIT: I think I just found it! It appears I need to ask for the slope to be inserted; it does not happen without express request. But if I am seeing this right, that is a miniscule price to pay, because this could very well be completely marvelous!

On a related topic: Is it possible to assign more than one IPO driver to the same IPO curve? For example, so that two different objects would both influence the X-rotation of, say, a cube?

Slope is the Y-value of the IPO Curve relative to the X-value (frames). A high Y-value over ten frames (or 100) will give you a steeper ‘slope’ than a lower one. And that all applies to the (single) IPO curve that the Driver is using.

Is it possible to assign more than one IPO driver to the same IPO curve?

Yes, each IPO curve is a dataset (a value) and like all other data in Blender can be linked to by other users.


Ok, how ?

With a python script? The “normal” transform properties doesn’t (seem) to provide a way.


On a related topic: Is it possible to assign more than one IPO driver to the same IPO curve? For example, so that two different objects would both influence the X-rotation of, say, a cube?
How exactly would this work? If Cube A and Cube B rotations both drive a Cube C rotation, then what exactly would Cube C do when Cube A is rotated but Cube B not rotated? Would Cube C NOT rotate, because Cube B says so or does it respond to Cube A or does it strike a happy medium and only half respond?

Sorry if it’s obvious, it’s 4am here. :slight_smile:

Sorry, I read that wrong. I thought the question was can two objects be driven by the IPO of one.

You can have two, but only two, different objects driving one axis transform of a third object if you put a Driver on each of the Axis and D-Axis IPO’s, but they cancell each other out.



I am having a FEAST with the IPO drivers right now! It seems to work with the whole slope thing, it was just something that had to be activated and was really not that obvious, so thanks a bunch for the info!

As for the “two in one”, I was thinking maybe something like how two or more Constraints can interact on one object. Seeing as I use dRot and dLoc IPO drivers mostly, the driven object could reasonably well be affected by either the sum of two or more drivers (turn Driver A 30 degrees and Driver B 60 degrees, and the driven object turns 90 degrees in total), or some form of calculated middle ground, as when tampering with Influence in Constraints.

In all honesty, I think Blender would profit greatly from a reworking of just the user interface in matters like Constraints and IPO drivers. There’s gold in them hills already, it is just messy digging it out. With a bit of rewiring, you could literally create miraculous systems with this stuff. I am still trying to figure one trick out, and if any of you guys want to take a shot at it, it might be an interesting test of Blender’s animation systems:

Create a rotor, as on a helicopter, the spinning speed of which is set entirely by a single ‘slider’, such as an empty (or a box) being moved up or down to raise or lower the rotor’s spinning speed throughout the animation.

It’s tricky, and I have yet to find an elegant solution. But it would pave the way for creating very advanced machinery (maybe even organic) models complete with integrated moving-part functions. Want to steer that vehicle by turning its wheels?

PS: I am posting a feature suggestion of providing sliders and numbe rbuttons which can be used as IPO drivers, allowing the user to create menu panels for driving animation objects. I just want to be sure: There is nothing like that already, is there? Also, I will suggest creating user-defined panels for sorting such user-defined buttons/sliders.