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Animate Dots to Appear like Rain Drops

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Shutian Chan
Animate Dots to Appear like Rain Drops
on Oct 29, 2019 at 2:43:07 am

Hi,

I'm pretty new to expressions on after effects.

I would like to animate dots to appear like raindrops. I tried following this:
https://www.schoolofmotion.com/blog/random-expression-after-effects

I've got over 500 layers of dots on individual layers created in illustrator and imported to After Effects as a composition.
Created an adjustment layer called 'Control' with slider controls:
- Change Seed
- Minimum Start
- Maximum Start

With each layer, i added a

- Frame Delay Slider with
seed = thisComp.layer("Control").effect("Change Seed")("Slider");
minStart = thisComp.layer("Control").effect("Minimum Start")("Slider");
maxStart = thisComp.layer("Control").effect("Maximum Start")("Slider");
seedRandom(index+seed,true);
randFrames=random(minStart,maxStart);

- Scale Expression with:
frameDelay = effect("Frame Delay")("Slider");
valueAtTime(time + framesToTime(frameDelay));

what I don't understand is the keyframes within each layer for scale and opacity:
13849_screenshotreduce.jpg.zip

I'm I doing this correctly to achieve a rain like dot animation? Any help is much appreciated.

Thanks!


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Julien Schickel
Re: Animate Dots to Appear like Rain Drops
on Oct 31, 2019 at 2:46:41 am

Maybe I don't understance what you're trying to do, but I find it very complicated. If you want your dots to fall from beyond the screen to under it like rain, with different times, position and scale, you may try a simpler kind of expressions like that (assuming your comp is in 1920x1080):

create a Null, with 2 slider control. (one renamed minStart, the other maxStart)

on position:
minStart=//pickwhip your slider control;
maxStart=//pickwhip your slider control;

seedRandom(index,true);
A=random([0,-50],[1920,-50]);
B=random([0,2000],[1920,200]);
T=random(minStart,maxStart);
linear(time,T,T+2,A,B)

on scale:
seedRandom(index,true);
S=random(0,100);
[S,S]

Julien


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Shutian Chan
Re: Animate Dots to Appear like Rain Drops
on Nov 4, 2019 at 2:18:36 am

Hi Julien,

Thank you for your reply.

I've tried what you've suggested, but it isn't quite what I was looking for.

I'm trying to get a series of dots (image 1) in different size to blink randomly, much like the example.
Image 1

I did the same set up as shown in the link, but my dots disappear after!!! Any suggestions on how to get the blinking animated effect, that feels like rain drops?


What i did:

Adjustment layer with 3 control sliders:
- Change Seed
- Minimum Start
- Maximum Start

Each dot on its own layer, and applied the following to each:
- Control Slider called " Frame Delay", with the following expression:

seed = thisComp.layer("Control").effect("Change Seed")("Slider");
minStart = thisComp.layer("Control").effect("Minimum Start")("Slider");
maxStart = thisComp.layer("Control").effect("Maximum Start")("Slider");

seedRandom(index+seed,true);
randFrames=random(minStart,maxStart);


- Scale, with the following expression
frameDelay = effect("Frame Delay")("Slider");
valueAtTime(time + framesToTime(frameDelay));


- Opacity, with the following expression
frameDelay = effect("Frame Delay")("Slider");
valueAtTime(time + framesToTime(frameDelay));




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Julien Schickel
Re: Animate Dots to Appear like Rain Drops
on Nov 4, 2019 at 1:16:07 pm

Ok, now I think I understand what you want to achieve. If I am correct, your expressions are ok, and the problem lies in your keyframing.

If you want your dots to be before and after your effect, both your first and last keyframes in both opacity and scale shall be at 100%.

For example, if you only want a random disappear/reappear (with a space between keyframes of ten frames every time):
on scale,
1st keyframe at 100,100, 2nd keyframe at 0,0, 3rd keyframe at 0,0, 4th keyframe at 100,100
on opacity (basically same thing)
1st keyframe at 100, 2nd keyframe at 0, 3rd keyframe at 0, 4th keyframe at 100.

From what I see from your screen, you miss at least one opacity keyframe.

Julien Schickel
Editor & motion designer
https://www.youtube.com/channel/UC7_NVR3JLdhEYDlEQuNFfug


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