I need help on rigging a window that closes (drops) when you move the empty
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Simple solution:
Add your empty and constrain it to move only from Z = 0 to Z = 5 - check For Transform box on the Limit Location constraint.
Add a Transform constraint to the first slat to fall - Target is the empty - check extrapolate button - set values for Z movement of target to min = 0 max = 1 set Z values for object to min = 0 max = distance you want it to drop with a minus sign in front e.g. -4 - keep World Space for both.
Move empty up 1 in Z - slat will drop the distance you specified.
Add identical Transform constraint to second slat EXCEPT Z values for target are now min = 1 max = 2 and distance to move same as before with negative sign.
Move empty up 2 in Z and first slat will move down again (this is what the extrapolate function does) and second slat will move down to where the first one was.
Repeat for next slat with target Z values as 2 and 3 - you should have the idea by now!
Complete for all slats and move the empty up and down.
I have done this post from my phone, no Mac with me just now, so can’t make a mockup for you - maybe later…
There are other ways, but this one is pretty straight forward.
Cheers, Clock