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Conditional expression problem
I’m trying to make a kind of a toggle from a null object that would switch on or off various layers in various compositions. When the Video switch (the eye symbol) of the null object would be turned on, the opacity of the linked layers would be turned 100. And when the Video switch of the null object would be turned off, the opacity of the linked layers would be turned to 0.
I’m a complete novice with AE’s expressions and I just can’t make this work. Maybe there’s something wrong with the syntax? Maybe I’ve misunderstood the way the “.active” attribute works.
This is what I came up with:
TOGGLE = comp(“ToggleComp”).layer(“NullObject”).active;
if TOGGLE = true 100 else 0sam
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6 Replies
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You can use the .active property, but it’s not the best solution. I would create a custom checkbox control on your dummy layer – this is much cleaner, especially in case you decide to add more custom controls later on. You could attach them all to this one layer instead of cluttering your timeline with multiple Null objects. Other than that, you should learn what brackets are for… Your expression does not work because there is no separation between the condition and the actual function. It should like that:
TOGGLE = comp(“ToggleComp”).layer(“NullObject”).active;
if (TOGGLE = 1){100}
else {0};For reasons of efficiency I replaced “true” with “1”.
Mylenium
[Pour Myl
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Close – the equality test uses the double equal sign – like this:
if (TOGGLE == true) 100 else 0
Dan
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Great, now it works, thanks a lot! 🙂
The After Effects User Guide doesn’t seem to say anything on the subject of conditional expressions. I suppose I should get one of those more in-depth tutorial books to get properly started with the expressions. Seems to be a quite powerful feature.
sam
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Ok, the checkbox control seems like a good idea.
The reason I was thinking of using the Video switch is that the finalized project is going to be used for a tv show on a weekly basis by more or less inexperienced After Effects users, ie. the video editors of the show. I’m trying to prepare the project so that it’s going to be very simple to add or remove pre-animated objects to the graphics by simple toggle switches. And the Video switch with its eye-symbol couldn’t be more clearer to use.
sam
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[Dan Ebberts] “Close – the equality test uses the double equal sign – like this:
if (TOGGLE == true) 100 else 0
Dan”
Ooops, how could I have overlooked that! It’s so good to have you around, Dan.
Cheers
Mylenium
[Pour Myl
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Hi all,
I just stumbled across this post as I’m searching for a way to link the visibility of a null object to a slider control of a master_control null object.I have a slider in the Master Control that controls the opacity of a body angle, switching between front, left, and right. I want to attach the visibility of the null objects to act in the same way!
Would the above mentioned expression work, and if so, where would I paste it?
Thanks a bunch!
Scott
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