Parenting expression needed

[Matt Paintin]

I want to create a handmade anamorphic lens flare and I wanted to have a basic control to animate its position.

What Im after is an expression that will allow me to parent the lensflare 'artwork' to a null/light source but will essentially make the flare move in the opposite direction from the null. Basically it would act like the positioning function of the standard AFX lens flare.

Can anyone suggest an expression that would get this working?

Thanks

[Mylenium]

http://aestuff.myleniumstuff.de/?p=7

Mylenium

[Matt Paintin]

Thanks for that Mylenium

Ive taken a look at the projects and the link to the tute on Creative Cow.

You have done a stunning job but I think its probably a bit too involved for me to get my head around to work out how you have implemented the math!

What would be the relevant basic expression that relates to a basic positioning set up?

[Dan Ebberts]

This shold mirror a layer across the center of the comp from a null or light named "flare":

mult = -1;
flare = thisComp.layer("flare");
compCenter = [thisComp.width,thisComp.height]/2;
compCenter + mult*(flare.toComp([0,0,0]) - compCenter);

Adjust the value of mult to adjust the distance.

Dan

[Matt Paintin]

Thanks so much for replying Dan

That too works very well . With help I have had from you and Mylenium I think I will be able to get some cool results now

Thanks again

Matt