Bounce Over Time

• Ball Bounce Simulation

elev = degreesToRadians(45); //elevation
v = 2000; //velocity
e = .7; //elasticity
f = .5; //friction
g = 5000; //gravity
nMax = 9; //maximum number of bounces
tLaunch = 0; //launch time

vy = v*Math.sin(elev);
vx = v*Math.cos(elev);
if (time >= tLaunch){
t = time - tLaunch;
tCur = 0;
segDur = 2*vy/g;
tNext = segDur;
d = 0; // x distance traveled
nb = 0; // number of bounces
while (tNext < t && nb <= nMax){
d += vx*segDur;
vy *= e;
vx *= f;
segDur *= e;
tCur = tNext;
tNext += segDur;
nb++
}
if(nb <= nMax){
delta = t - tCur;
x = d + delta*vx;
y = delta*(vy - g*delta/2);
}else{
x = d;
y = 0;
}
value + [x,-y]
}else
value

• Keyframe Bounce

e = .7; //elasticity
g = 5000; //gravity
nMax = 9; //maximum number of bounces

n = 0;
if (numKeys > 0){
n = nearestKey(time).index;
if (key(n).time > time) n--;
}
if (n > 0){
t = time - key(n).time;
v = -velocityAtTime(key(n).time - .001)*e;
vl = length(v);
if (value instanceof Array){
vu = (vl > 0) ? normalize(v) : [0,0,0];
}else{
vu = (v < 0) ? -1 : 1;
}
tCur = 0;
segDur = 2*vl/g;
tNext = segDur;
nb = 1; // number of bounces
while (tNext < t && nb <= nMax){
vl *= e;
segDur *= e;
tCur = tNext;
tNext += segDur;
nb++
}
if(nb <= nMax){
delta = t - tCur;
value + vu*delta*(vl - g*delta/2);
}else{
value
}
}else
value

• Keyframe Overshoot

freq = 3;
decay = 5;
n = 0;
if (numKeys > 0){
n = nearestKey(time).index;
if (key(n).time > time) n--;
}
if (n > 0){
t = time - key(n).time;
amp = velocityAtTime(key(n).time - .001);
w = freq*Math.PI*2;
value + amp*(Math.sin(t*w)/Math.exp(decay*t)/w);
}else
value

REF: Motionscript.com bounce-and-overshoot


veloc = 20; 

amplitude = 10; 

decay = .8; 

y = amplitude*Math.cos(veloc*time)/Math.exp(decay*time);

value + [0,y]

Start, Stop Expression from Adobe (REF)

You can use any expression in place of the wiggle expression used here, to begin and end the influence of any expression at a specific time.

• Apply the following expression to a property to wiggle it beginning at time 2 seconds:

    timeToStart = 2; 
    if (time > timeToStart){ 
        wiggle(3,25); 
    }else{ 
        value; 
    }

• Apply the following expression to a property to stop wiggling it at time 4 seconds:

    timeToStop = 4; 
    if (time > timeToStop){ 
        value; 
    }else{ 
        wiggle(3,25); 
    }

• Apply the following expression to a property to start wiggling it at time 2 seconds and stop wiggling it at time 4 seconds:

    timeToStart = 2; 
    timeToStop = 4; 
      
    if ((time > timeToStart) && (time < timeToStop)){ 
        wiggle(3,25); 
    }else{ 
        value; 
    }

Offset Controller

Create an adjustment layer and apply Slider Expression Controls named "Offset Controller"

Apply code to layer that needed offsetting. Duplicate layer on how much thickness you need.

[Start]
X = (index-1)*thisComp.layer("Offset Controller").effect("Offset")("Slider");
Y = (index-1)*thisComp.layer("Offset Controller").effect("Offset")("Slider");

Z = (index-1)*thisComp.layer("Offset Controller").effect("Offset")("Slider");

value + [X,Y,Z]

[End]