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Slider expression not working when keyframes added
Hi guys!
Long time lurker, first time poster. Apologies in advance if this has been covered elsewhere (I’ve scoured other threads but haven’t found a solution)
I have a Slider expression that is set up to control the opacities of 3 layers. The Slider Value Scale is set between 0 – 100.
Basically the expression states that if the value of Slider A is between a certain range then the opacity for that given Layer is 100 else 0.
So let’s the call them “Layer A” “Layer B” “Layer C”The expressions for each are:
“Layer A” : if(comp(“Comp A”).layer(“Layer 1”).effect(“Slider A”)(“Slider’)<=25)100 else 0
“Layer B” : if(comp(“Comp A”).layer(“Layer 1”).effect(“Slider A”)(“Slider’)>=26 && comp(“Comp A”).layer(“Layer 1”).effect(“Slider A”)(“Slider’)<=50))100 else 0
“Layer C” : if(comp(“Comp A”).layer(“Layer 1”).effect(“Slider A”)(“Slider’)>=51 && comp(“Comp A”).layer(“Layer 1”).effect(“Slider A”)(“Slider’)<=75)100 else 0
The expressions themselves check out. When I adjust the value of the Slider scale the layers’ opacities adjust accordingly. However as soon as I try to keyframe the slider values, the expression freezes to whatever the first keyframe value is. So basically if “Layer B” is visible when I start key-framing, only “Layer B”. will be visible from that point forward, no matter the change in Slider value.
I hope I’ve explained this thoroughly enough. I’m very confused as to why the keyframes would be the issue. I thought initially that I might have too many compositions and too many expressions, however I stumbled across a thread where someone said they have “600 comps and 8000 expressions” and everything works fine.
Is there some setting that I’m missing here? It’s only been a problem within this composition.
Any help would be much appreciated. Thanks in advance!
-Del
"Layer A" : if(comp("Comp A").layer("Layer 1").effect("Slider A")("Slider')<=25)100 else 0"Layer B" : if(comp("Comp A").layer("Layer 1").effect("Slider A")("Slider')>=26 && comp("Comp A").layer("Layer 1").effect("Slider A")("Slider')<=50))100 else 0
"Layer C" : if(comp("Comp A").layer("Layer 1").effect("Slider A")("Slider')>=51 && comp("Comp A").layer("Layer 1").effect("Slider A")("Slider')<=75)100 else 0
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5 Replies
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This will happen when you’re referencing a keyframed in (or from) a precomp and the precomp doesn’t start at time zero in the main comp. You have to compensate for that offset in your expression by using valueAtTime() with an offset equal to the start time of the precomp layer in the main comp. The exact code depends on how you have things set up.
Dan
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All three lines had typos in them that had to be fixed before this worked at all. Single quotes and missing parenthesis. Once fixed, I had no problem keyframing them.
Layer A
if(comp("Comp A").layer("Layer 1").effect("Slider A")("Slider")<=25)100 else 0
Layer B
if(comp("Comp A").layer("Layer 1").effect("Slider A")("Slider")>=26 && comp("Comp A").layer("Layer 1").effect("Slider A")("Slider")<=50)100 else 0
Layer C
if(comp("Comp A").layer("Layer 1").effect("Slider A")("Slider")>=51 && comp("Comp A").layer("Layer 1").effect("Slider A")("Slider")<=75)100 else 0Or, if that doesn’t do it, what Dan said.
Kalleheikki Kannisto
Senior Graphic Designer -
Dan, once again you are a frickin’ genius. Thank you so much
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Hi Dan,
I’m experiencing the same kind of problem. I made a full rig of a character with head turns in 5 different positions. The slider control is used for the blink. The way I have my rig set up is:
Eye Comp: 5 positions (side, 3/4, front, 3/4, side), with 3 layers each: open, half closed, closed
Eye pose comp: contains three layers (three of the eye comp), in which I wrote an expression for the slider: if (s = 0) {100} else {0}, and so on for s = 1 and s = 2.
Eye pose comp is in the head comp, where head is linked to head control slider.
Head comp is in the main rig
rig is imported into main comp
so with this set up the slider works perfectly until I keyframe the slider control in the rig comp. How would I proceed to fix this problem?
Thank you so much! -
It could be complicated, if you have to compensate for every level of comp nesting. However, I’m guessing that going up the heirarchy, there aren’t many instances where the nested comp layer doesn’t start at time = 0 in its parent comp. If you can identify those situations, it will simplify the code.
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