Link Scale to Z Position

[t***@adobeforums.com]

Is there an expression that will let me link [x,y,z] of a 3D Camera to [x,y,scale] of a 2D layer?

[R***@adobeforums.com]

The zoom value of the camera lens divided by the length between the camera and the 2D layer should give it to you. Try this:

cam = thisComp.layer("Camera 1");
cp = cam.position;
lp = position;
d = length(cp, lp)
z = cam.zoom;

[z/d*100, z/d*100]

This will keep your 2d layer the same size relative to 3D layers in the comp no matter what the camera position.

[t***@adobeforums.com]

Great, except I think it's backwards. I need a 2D Mocha track which yields x,y and scale to drive the camera and align 3D layers (particles) with the 2D plate.

Thanks for your help Rick.

[R***@adobeforums.com]

That will take a little more work. I can't do it in my head. If I get time this evening I'll try and figure out something.

Rick

[t***@adobeforums.com]

I'm working diligently as well, although I am not very good with expressions. If I come up with something I will post as well.

Thanks again.