Expression to switch on objects beneath matte

[Matthew Ingram]

really hoping someone has an idea on this 🙂

[Dan Ebberts]

Assuming the matte is a layer, something like this should work:

m = thisComp.layer(“matte”);
p = m.fromComp(toComp(anchorPoint));
a = m.sampleImage(p,[width,height]/2,true,time)[3];
a < .5 ? 0 : 100

Dan

[Matthew Ingram]

thanks dan – i’m honoured by your presence.

i applied it to the transparency of the layers below and (as the saying goes) BOOM. perfect.

[Matthew Ingram]

hi dan (or if anyone else is tuned in…)

is there a way to tailor this script so that the layers scale up from zero rather than their opacity switches on?

would be great to know!

many thanks.

[Dan Ebberts]

Let me ask you this–is there any animation going on, or, if a layer is under the matte, it’s always under the matte? (It makes a big difference to how complicated the expression would be).

Dan

[Matthew Ingram]

thanks dan 🙂

apart from the scaling up – no there wouldn’t be any other animation (they are preComps – so i can put animation in there)

yes – everything could be under the matte.

very much appreciated

matt

[Dan Ebberts]

Something like this then probably:


m = thisComp.layer("matte");
scaleTime = .5;
p = m.fromComp(toComp(anchorPoint));
a = m.sampleImage(p,[width,height]/2,true,time)[3];
if (a < .5){
[0,0];
}else{
ease(time,inPoint,inPoint+scaleTime,[0,0],[100,100])
}


Dan

[Matthew Ingram]

beautiful. thank you 🙂