Scale / Position Expression

[Darby Edelen]

You’ll need to determine the layer’s distance from the vertical center of the composition and then vary the scale based on that.

Here’s one possible implementation:


f = 2; //factor to increase scale by
min = 0; //distance in pixels from the center where the layer is at full scale
max = 300; //distance in pixels from the center where the layer is at 'normal' scale
c = [thisComp.width / 2, thisComp.height / 2]; //center of the composition
p = toComp(anchorPoint); //location of the current layer in the composition
d = Math.abs((p - c)[0]); //distance from the center along the x-axis
ease(d, min, max, f * value, value);


Darby Edelen

[Rafael Cruz]

Thanks for your help Darby.
Simple, functional, great.
How would I apply this expression to the y-axis?

[Darby Edelen]

Do you want it to scale based on the distance from the center without regard for the axis? Or do you only want to take into account the distance along the y axis?

Darby Edelen

[Rafael Cruz]

I am looking to apply the expression solely to the y-axis.

*out of curiosity*
I’d like to try swapping scale for z-axis position. The idea being that when I move the image toward center-screen (say, on the y-axis) the image advances on the z-axis.
If it’s not any trouble if love to know how I could work a tweak like that as well.

Again, thanks for your time.

[Rafael Cruz]

I hope I wasn’t asking for too much in my last post.
I really appreciate the help you given so far, and if possible I’d love to know how to epply the expression you suggested on the y-axis.

[Filip Vandueren]

f = 2; //factor to increase scale by
min = 0; //distance in pixels from the center where the layer is at full scale
max = 300; //distance in pixels from the center where the layer is at 'normal' scale
c = [thisComp.width / 2, thisComp.height / 2]; //center of the composition
p = toComp(anchorPoint); //location of the current layer in the composition
d = Math.abs((p - c)[0]); //distance from the center along the x-axis
ease(d, min, max, [value[0], f * value[1]], value); 




z = -500; //value to move in Z
min = 0; //distance in pixels from the center where the layer is at full scale
max = 300; //distance in pixels from the center where the layer is at 'normal' scale
c = [thisComp.width / 2, thisComp.height / 2]; //center of the composition
p = toComp(anchorPoint); //location of the current layer in the composition
d = Math.abs((p - c)[0]); //distance from the center along the x-axis
ease(d, min, max, [value[0], value[1], value[2]+z], value); 

To stretch only the Y-axis (I assume that’s what you meant) try the first exp.

For subtracting from the z-value of position try the second.

[Rafael Cruz]

Thanks for your time and help Filip.

I need to clarify my request. Darby posted an expression which increased the scale of an image as it approached center-screen on the x-axis alone. So the image grows and shrinks normally as it changes position along the x-axis only (based on it’s position relative to the center).

I would like to do the same the the position of the image along the y-axis.

[Filip Vandueren]

Ok in the second to last line of darby’s expression just change the final [0] to [1]
meaning you want to look at the second element of the array that describes position (y) instead of the first (x)

[Rafael Cruz]

Thanks Filip!
So simple.
And yet it would have taken me quite a while to figure out.

[Darby Edelen]

Sorry I hadn’t checked in on this thread in a while 🙂

Changes to my original code are in bold. Hopefully this helps you break the parts down a bit more conceptually.

You would apply this to the position property on a 3D layer.


offset = -500; //distance to move on the z-axis
min = 0; //distance in pixels from the center where the layer is at full scale
max = 300; //distance in pixels from the center where the layer is at 'normal' scale
c = [thisComp.width / 2, thisComp.height / 2]; //center of the composition
p = toComp(anchorPoint); //location of the current layer in the composition
d = Math.abs((p - c)[1]); //distance from the center along the y-axis
z = ease(d, min, max, offset, 0);
value + [0,0,z]

Darby Edelen