object on a string damping

[Dan Ebberts]

Try this:

g = 3500; // gravity (pixels/second/second)
floor = 400;
e = .35; //elasticity

b = floor – position[1];
h = b;
T = Math.sqrt(2*h/g);

if (time < T){ y = - g*time*time/2 + b; }else{ Vy = g*T; while (true){ Vy *= e; t = T; T += 2*Vy/g; if (time < T){ t = time - t; y = Vy*t - g*t*t/2; break; }else if (T - t < thisComp.frameDuration){ y = 0; break; } } // end while } [value[0], floor - y] Dan

[Göran Thorén]

What can I say.. Dan you´re the man!
Thank´s a million!

Husse

[Adam Lukas]

What exactly is this expression applied to? sorry this is such a noob question…

[Adam Lukas]

never mind, i figured out what i was doing wrong 🙂

[Dan Ebberts]

The Position property.

Dan

[Brad Hilton]

will this work in cs5?

cause im getting an error message.

After Effects warning: Timeout while waiting for the engine
Expression disabled.

Error occurred at line 16.
Comp: ‘Cloud2’
Layer: 1 (‘Vector Smart Object’)
Property: ‘Position’

g = 3500; // gravity (pixels/second/second)
floor = 400;
e = .35; //elasticity

b = floor - position[1];
h = b;
T = Math.sqrt(2*h/g);

if (time < T){
y = - g*time*time/2 + b;
}else{
Vy = g*T;
while (true){
Vy *= e;
t = T;
T += 2*Vy/g;
if (time < T){
t = time - t;
y = Vy*t - g*t*t/2;
break;
}else if (T - t < thisComp.frameDuration){
y = 0;
break;
}
} // end while
}
[value[0], floor - y]

[Dan Ebberts]

You’ll get that error if you start your bouncing layer below the “floor” (y = 400 in this case).

Dan

[Jerry Adams]

well..this is too hard for me… can enyone do a tut for this effect…pls?