After Effects Layer Properties Interaction

Question

Just new here :)

I want to be able to do 2(-ish) things on my layers on After Effects.

(Layer 1 = l1; Layer 2 = L2; Blur amount = BA)

Increase L2’s BA whenever I increase L1’s BA. (Or the opposite, decrease BAs)
Change L2’s opacity to 0% if L2’s BA is 0 and it’s opacity to 100% if L2’s BA is >1 or <1.

Essentially I’m trying to make these individual properties interact with each other without using too much slider controls.

Answer 1

For the blur, just use the pick-whip to link the properties. you might want to read up on how to link properties with expressions using the pick whip.

For the opacity, you'll need some javascript. what you want to do is set the opacity of L1 to if L2 blur is 0 then 0, or else if it's not equal to 1 then 100%.

let L2 = thisComp.layer("layer 2 name");
//use the pick whip to get the actual property name here
let blurAmt = l2.effect("Blur effect name")("Blurriness or whatever"); 
//set the opacity to 0 if bluriness is 0 '===' means 'exactly equal to'
if (blurAmt === 0){
    0
} else if (blurAmt != 1) { //'!=' means 'not equal to'
    100
} else {
    ???? // you haven't specified what you want the opacity to be if L2's blur is 1
}