Getting 2 Empties to move opposite eachother on the Z Axis

Okay - I was messing around with the TaperOb function today and I finally got it to work.

Here’s what I’m trying to do: I want to maintain the reverse symmetry on the two control curves that I have so that my resulting shape will look nice. I parented some empties to the same vertex on each curve and that works fine. Now I want them to move in opposite directions when I move what I assume will be one parent up or down. In other words, I want them to move away when I pull one away from the center that they share and closer when I move them towards it.

I would use Copy Location, but it doesn’t have any -z -x or -y buttons, only the positives. Track to is only for rotation, and Follow Path seems only to be for paths. Is there a trick or script somewhere that I should be using?

Copy and paste this, then have a look:


I had asked something similar not oh-so-long-ago, perhaps sketchy’s blend is what you are looking for…

For simple movements like this you could use IPO drivers. For example, create an IPO for LocZ on Empty1, N-key to add a driver. Speecify Empty2 as the driver OBject, and select LocZ as the driver channel. Use I-key to create a 1-to-1 curve. You have to shift the resulting IPO curve down a bit so Empty1 starts in the right place. Now when you move Empty2 on the Z axis the other’s movement will be “reflected.”

Thanks. The DRIVERS will work just fine once I get the coordinates sorted out.