keyframing expressions?

[Chad Gilmour]

I’m not sure, I’m thinking no, but I basically use expressions pickwhipping abilities and not much more than that.
A work around I’d sugest is maybe moving the playhead to where you want the layer to “change” expressions and pressing ctl/cmd+shift+D which will duplicate your layer and split it at the point of the playhead, then I would change the expression for the newly created layer.
It’s a very fast and efficient way to do stuff similiar to what your describing.

[Benjamin Tubb]

Nah, that won’t work for what I’m doing. I have the corner pin effect on Layer 1. I need one of it’s corners to track a tracking point up to a certain amount of time, and then change to a different tracking point. And do it again, and again… Thanks though…

“Of course, I could be wrong. In fact, I’m probably wrong.”

[Jerzy Drozda jr]

sure you can:

if((0 < time) && (time<10)){ // first expression } else { // second expression } for the first 10 seconds execute first expression, then use the second one.

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maltaannon.com – Free After Effects Video Tutorials and more

[Benjamin Tubb]

Okay, that helps… but then how do I change it again after that? It needs to use a total of 4 different tracking points over time.

“Of course, I could be wrong. In fact, I’m probably wrong.”

[Kevin Camp]

you could use layer markers to indicate the point at which the target should change, the use an expression like this:

target1 = ;//point at 1st target
target2 = ;//point at 2nd target
target3 = ;//point at 3rd target
target4 = ;//point at 4th target
if (time < marker.key(1).time) value; if ((time >= marker.key(1).time) && (time < marker.key(2).time)) target1; if ((time >= marker.key(2).time) && (time < marker.key(3).time)) target2; if ((time >= marker.key(3).time) && (time < marker.key(4).time)) target3; if (time >= marker.key(4).time) target4;

you could probably link the timing to the target layers’ in and out points so you wouldn’t need the layer markers if you needed to be super flexible.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW

[Kyle Hamrick]

Based on your descriptions of what you’re doing, you also might consider simply applying your track data from the multiple sources to a single Null, then using that as your actual track point. Depending on the specifics, that may be easier to deal with than some big, messy expression.

Kyle Hamrick

Editor/Motion Graphics Artist

http://www.kylehamrick.com

[Benjamin Tubb]

Kevin, your idea might do it. That’s interesting, I never knew expressions could interact with layer markers.

Kyle’s idea is good too, but not all of my ‘tracking points’ are actually ‘tracking points’. Some of them are Point Controls animated by hand frame by frame.

Thanks for all the help

“Of course, I could be wrong. In fact, I’m probably wrong.”