Create a falloff

[Tomas Sinkunas]

Hello guys. I know this is probably something simple, but I cannot wrap my head around it.

I have a scene with 4 layers (L1, L2, L3, L4) that are parented each to another and one null layer as a controler. This control null has Slider (Falloff) and Angle Control (ROT).

What I want to create is a sort of falloff effect that work something like this:

- If falloff value is at 0:

     - changing ROT 0 - 180:

          - L1 rotates from 0 to 180;

          - L2 rotates from 0 to 180 once L1 has rotated to 180 value

          - L3 rotates from 0 to 180 once L2 has rotated to 180 value

          - L4 rotates from 0 to 180 once L3 has rotated to 180 value

- If falloff value is at 100:

     - changing ROT 0 - 180:

          - L1 rotates from 0 to 180 * 4 (because we have 4 layers and this is 4th layer in a row);

          - L2 rotates from 0 to 180 * 3 (because we have 4 layers and this is 3rd layer in a row);

          - L3 rotates from 0 to 180 * 2 (because we have 4 layers and this is 2nd layer in a row);

          - L4 rotates from 0 to 180

and all those in between values.

I have this expression right now, but it just doesnt seem to work as I want it to.

Any help?

var i = thisLayer.index;
var max = 180;
f = 1 - (thisComp.layer("controller").effect("Falloff")("Slider") / 100);
rot = thisComp.layer("controller").effect("ROT")("Angle")

value = linear (rot, i*f*max, i*f*max + max, 0, max)

[Mylenium]

Swap the positions in your linear expression. You have things backwards there.

Mylenium

[Tomas Sinkunas]

Linear expression seems to be OK in my example.

linear(t, tMin, tMax, value1, Value2), where:
t - rotation value,
tMin - lowest rotation value i * f * max
tMax - maximum rotation value i * f *max + max
Value1 - 0;
Value2 - max rotation allowed

[Mathias Moehl]

why is value2=180?

for falloff = 100 you say you want to have L1 rotates from 0 to 180 * 4 which is > 180

Maybe you try to split up the issue in 3 separate linear constructs?

var case1 = linear(here goes what I want to have for falloff == 0);

var case2 = linear(here goes what I want to have for falloff == 100);

var result = linear(falloff, 0,100, case1, case2);

[Tomas Sinkunas]

This is probably the case where having the project file at hand is the way to go.

Dropbox - falloff.aep

Mathias, not really sure how to use your suggestion here.

[Mathias Moehl]

I think this is implementing exactly your specification. If this is not what you want, you need to explain more precisely what you want:

var i = thisLayer.index;
var max = 180;
var numElements = 4;
falloff = thisComp.layer("controller").effect("Falloff")("Slider");
rot = thisComp.layer("controller").effect("ROT")("Angle")


// when falloff = 0 split the total range [0,max] such that Li starts rotating when Li-1 finished rotating
var maxPerElement = max/numElements;
var myRangeStart = (i-1)* maxPerElement;
var myRangeEnd = myRangeStart + maxPerElement;
var fallOff0Result = linear(rot,myRangeStart,myRangeEnd,0,max);

// when falloff = 100 Li rotates from 0 to 180 * i
var fallOff100Result = linear(rot,0,max,0,max*i);

// blend between the two extreme cases for falloff
linear (falloff,0,100, fallOff0Result, fallOff100Result)

[Tomas Sinkunas]

Thank you Mathias Moehl‌ for your answer, it's really good one, but unfortunately that's not exactly what I need.

I did a mistake in first post about what I need. Apparently I do not want to change rotation value - only falloff value and falloff position.

However, as I am not able to do this in AE, I went to C4D and recreated scenario that I need. Mind taking a look?

Dropbox - falloff.c4d

Also here's a picture that illustrates what I am after. Here's a bigger one Dropbox - falloff.png

Still, really grateful for your reply Mathias.

[Mathias Moehl]

I didn't look at the C4D file, but from the picture I guess you want something like this?

var i = thisLayer.index;  
var max = 180;  
var numElements = 4;  
falloff = thisComp.layer("controller").effect("Falloff")("Slider");  
rot = thisComp.layer("controller").effect("ROT")("Angle")  

// when falloff = 0 split the total range [0,max] such that Li starts rotating when Li-1 finished rotating  
// when falloff = 100 the ranges start at the same time as for falloff = 0 but all of them last until the end (i.e. they overlap)
var maxPerElement = max/numElements;  
var myRangeStart = (i-1)* maxPerElement;  
var myRangeEndForFalloff0 = myRangeStart + maxPerElement;  
var myRangeEndForFalloff100 = max;
var myRangeEnd = linear(falloff,0,100,myRangeEndForFalloff0, myRangeEndForFalloff100);
linear(rot,myRangeStart,myRangeEnd,0,max);  

[Tomas Sinkunas]

This is really close to what I need. But still not exact.

Will have to pick my brains some more then:)

Thanks Mathias Moehl‌ your script gives me a good start at it. Cheers.