aenhancers

Hi,
I have a null with some tracking information. I would like to move the lens flare center according to it.
What expression could I use to to parent a property rather than the entire layer?

Amit

You should be able to just add an expression to the Lens Flare Center property and drag the expression pickwhip to the null's Position property. Which will give you an expression like:

yes, I did that but it doesn't parent it. Its just follows the null's position which is way far off.

There's no built in way to do something exactly like parenting with expressions, but you can put in an offset. Something like:

also, not helping if the tracking data has rotation values.

I don't really see how rotation comes into it. There's almost certainly a way to do it but maybe you could describe better exactly what's going on, or even better, post a reduced project.

Dan Eberts posted this expression as a reply to this query, but in another forum...

L = thisComp.layer("Null 1");
p = L.transform.position;
r = L.transform.rotation;
d = valueAtTime(0) - p.valueAtTime(0);
angle = degreesToRadians(r - r.valueAtTime(0));
s = Math.sin(angle);
c = Math.cos(angle);
x = d[0]*c - d[1]*s;
y = d[0]*s + d[1]*c;

p + [x,y]