changing faces

[Filip Vandueren]

I would precompose and sequence the frown and smile, then add a similar expression to time remapping that toggles between frame 0 and 1.

Another approach could be two layers with inverted expressions for opacity, one is visible when the other ones not.

[Quentin Block]

Thank you. This makes sense.
I’m not sure how to create the expressions for opacity, or time remapping that toggles between frame 0 and 1.
Any suggestions?
Once I go to the pulldown menu and add an expression (on opacity for a particular layer), it just says “opacity” on the layer. I don’t know what to do after that…
I’d like to learn how to create some of these simple expressions but I don’t know the language yet…
Can you possibly give me a sample script or pointers how to do this?
Thanks so much!

[Filip Vandueren]

Ah, now I see it’s Mylenium’s script,

I thought you knew some basics…

anyway, a simple way for controlling the opacity would be this:
(this assumes it’s the layer’s own X-scale that needs to control it’s opacity)

expression for opacity of the smile:

xscale=scale[0];
xthreshold=80;
if (xscale>xthreshold) {
100
} else {
0
}

the frown layer would be exactly the same, only swap 100 and 0.

I think this expression kind of speaks for it self, one thing to note is this:
scale is an array with 2 or 3values (for x, y and possibly z) the first element in an array is called element 0 (that’s computer logic for you)
so scale[0] means the first value of the scale-array, so that’s the x-scale

the value of xthreshold should be set to the value at which you wan’t it to switch.

for timeremapping you basically need the same expression, just use 1 and 0, but mind you 1=1 second, so put the smile at 1 second, and the frown at the start of the precomp.
I would use the timeremapping: it uses fewer layers.

BTW: the same thing can be written in 1 line:

scale[0]>80 ? 100 : 0;

this means exactly the same:

is scale[0] bigger than 80 ? QUESTION MARK

result=100

else: COLON

result=0;

so “A?B:C” is short for “if(A) { B } else {C }”

and if you need another layer’s scale to control the opacity, you’ll need something like:

thisComp.layer(“Audio Amplitude”).scale[0]

the pickwhip comes in very handy to ‘pick up’ references like those, you can find more info about that in the manual.

[Quentin Block]

Filip,
Thanks very much for your explanation and your time.
I wll try out all of this.
Cheers!