Channel Drivers and Keyframes

Can I set up my animation so that it uses IPO’s between certain keyframes and drivers between others? or change how the driver drives the animation during certain frames?

Interesting, what if you animated a companion empty and then in your pydriver looked at what frame you are on and used the IPO data from the empty for some frames and the pydriver code for others?

Not skilled enough with python do to a single line IF statement, I’m afraid. There SHOULD be a way, though… Hmm. Definatly have the drivers affect the empty, I think… and then have a copy loc/ rot maybe with the Influance IPO’d might get what I want. Lets see if it works, shall we?

What exactly are you trying to achieve ?

Without knowing what you’re trying to do, my guess is to use separate blend files for each “type” of animation.


Actually I could see that being used in a walk cycle. The kind where the master bone moves, and the feet move backwards when they hit the ground.

Supposed whenever the feet hit the ground, they get driven by this object, which is the exact inverse of the master bone’s movement. That would be kind of neat.

Ah. I’m modeling thrill rides for an opensource project called Theme Park Builder 3D, and I wanted to create a test animation. The problem is/was that the ride I am presently modeling as a great deal of user interaction that I wanted to simulate by adding randomness to the ride motion. I’m trying to get an effect that will look similar to this:

As you can see, once the arms reach a certain height the riders can move the arms up or down and roll the car from side to side. To me this seems like an excellent spot for a pydriver that includes a randomnumber function; but only between certain times during the animation, since I have to return both the cars to upright and the arms to 75degree down rotation at the end to allign them with the ‘load’ platform.

S.R, check out the link above for real time mouse / IPO recording, may prove useful.

Another option is using the game engine to add random animation. There is a random “brick”, but I’ve never used it, you could probably get help on it in the g.e. forums.


Hmm… Using the G.E. is a whole other can o worms I’ve not mastered yet. Thanks for the link, that might help. bookmarked it for future refference too.

There’s a lot of different ways to come up with animation, but if you decide to go with your original idea or something like Atom suggests, there’s an easy way to make what are effectively multiple line pydrivers. Go to and look under the section “The Blender text”.

Basically, you can load a specially named python file into Blender’s Text Editor and use any functions or variables declared in it in your pydriver. Now the full power of Python is at your command!