After Effects - Echo Effect

[Raja.B.]

Is it possible for "Echo effect" to fade out ? Like can we use some expression to fade out the opacity of the echo effect. For example I have a Vector - Rain drop image. And I pre-comped that image and added echo to it. Now I wanna animate the rain drop to fall down from top to bottom. So I created a path layer in the Y axis from top to bottom. I copied the path and pasted it onto the position of the raindrop vector image. So it looks like it's going from top to bottom. Now what I wanna achieve is when the raindrop reaches the ground or like the bottom of the comp I want it to fade out. Is that possible with Echo effect ? Or can I add some expression in the opacity of the vector image ?

[Mylenium]

Technically the effect itself will just "fade" after the echoes' duration has expired, so I'm not sure what you are asking. If you need more control, the best way to proceed is usually to use a duplicate of the original pre-comp and place it at the end of the echoed segment, then control the timing with conventional opacity animation, masks and so on. It may also make more sense to animate a few droplets more and use time-remapping to repeat the cycle instead of letting an effect calculate the multiplied instances.

Mylenium

[Raja.B.]

I'm genuinely sorry, but I'm a little beginner. Can you please explain it more simpler or in a much easier way ? I do apologize for this.

[Rick Gerard]

You can animate opacity based on position. If the Y value where you want the layer to start fading out is 900, and the Y value when you want the raindrop to disappear is 1000, then adding this expression to Opacity will do the trick.

t = thisLayer.position[1];
tMin = 900;
tMax = 1000;
value1 = 100;
value2 = 0;
ease(t, tMin, tMax, value1, value2)

Another option would be to pre-compose all your falling raindrops, then add a gradient that goes from Black to White above the layer and set it as a Luma Track Matte. Now everything under the white will be visible, and everything under the black will disappear. If you use a shape layer for the gradient, it is easy to drag the start and end points of the gradient where you want them to be.

[Raja.B.]

Okay. I understood the pre-comp and using the gradient option. I'll surely try that. Just one question for the expression part. Will that work with Echo effect ? Because technically it's still one vector image that has an echo trail. I didn't use mutiple vector images and animated their position from top to bottom right. So will that work for every individual echo ? I mean the opacity expression. 

[Rick Gerard]

If you set up the opacity based on position expression on one or more shape layers, then Pre-composed, then applied Echo to the pre-comp, it will work fine. If you do not pre-compose, as soon as the layer fades out, all of the echos will fade out also, so it won't work. It's a render order thing that can only be fixed by pre-composing before you apply Echo.

I attached a simple comp to the post.

[Raja.B.]

Wow. Thank you so much. 🙂

[Byron Cortez]

The simplest is to animate the drops or create multiple instances of one, precompose them, and then apply a feather to the mask at the edge. Another option instead of a mask can be a Linear Wipe effect to the containing precompose of all the drops.

[Raja.B.]

Oh yeah. Will try this too. Thank you very much. 🙂