luma to drive animation of multiple comps

[Wim Bruyninckx]

Hi,

not sure of this will help you but;

I would suggest to use the nifty expression sampleImage() in the scale property layer
of each comp you want to scale in your array :

the expression would be:
100*[thisComp.layer(“GreyscaleMap”).sampleImage(position)[0],thisComp.layer(“GreyscaleMap”).sampleImage(position)[0]]

position = the position of your current comp you want to scale
where GreyscaleMap = your fractal map…
multiply it by 100, because sampleimage returns a value between 0 and 1.

Kind Regards

Wim

graphic designer / illustrator

https://www.flickr.com/photos/wixwix/
https://www.wimbr.be

[Dan Ebberts]

It would probably be like this:

target = thisComp.layer(“background”);
rgba = target.sampleImage(target.fromComp(toComp(anchorPoint)), [.5,.5], true, time);
luma = rgbToHsl(rgba)[2];
[luma,luma]*100

Note that this is set up for a 1-pixel sample–you might want a larger area, depending on your setup.

Dan

[Andy Acourt]

thanks for this, unfortunately I cant get it to work and I’m sure its me.
the fractal is on layer 1 and called “GreyscaleMap”
the comp I want to scale is on layer 2 and called “comp”
I’ve applied the script to scale property of the “comp” layer

and thats where my understanding falls apart – any more help would be greatly appreciated.

thanks

[Wim Bruyninckx]

make sure you precomposed the fractal layer, otherwise it won’t work

[Andy Acourt]

thanks for both of your help, especially Dan, it worked in the end. The problem was the fractal map had 3D turned on. As soon as I turned it off the script worked.