Expression at a specific time

[axelv]

Hi,

when I apply an expression it starts from the beginning of the composition, but if I want to start it, for example, after 10 seconds, how can I?

Sorry for my english.

[maxweel]

You can check the current time with the time variable:

if (time >= 10)
{
    // your expression
}
else
{
    // return the actual value you entered manually
    value
}

[axelv]

Thanks for reply but I don't understand very well.

My expression is:

k=130;

a=5;

b=12;

x=k*(1-Math.exp(-a*time)*Math.cos(b*time)); [x,x]

What should I do?

[maxweel]

Simply put your expression in place of "// your expression" !

if (time >= 10)
{
    // This will only be executed from 10 s
    k = 130;
    a = 5;
    b = 12;
    x = k*(1-Math.exp(-a*time)*Math.cos(b*time)); [x,x]
}
else
{
    // return the default value
    // in this case the default value is the propertie's value but you can put whatever you want here
    value
}

[Dan Ebberts]

I'm guessing you're looking for something like this:

timeToStart = 10;

t = time - timeToStart;

if (t > 0){

  k=130;

  a=5;

  b=12;

  x=k*(1-Math.exp(-a*t)*Math.cos(b*t));

  [x,x]

}else

  value;

If you want it to start at the layer's in point, just change the first line to this:

timeToStart = inPoint;

Dan

[axelv]

Thanks Maxwell and Dan!

Now I should make an expression for a bouncing text.

I should like the bottom and width are blocked and the text appear with a bounce of Y axis.

The Y axis go from 0 to 100 and bounce...Can you help me? Do you understand?

[axelv]

There is a problem!

If I use this expression

timeToStart = inPoint;

t = time - timeToStart;

if (t > 0){

  k=324;

  a=5;

  b=12;

  x=k*(1-Math.exp(-a*t)*Math.cos(b*t));

  [x,x]

}else

  value;

at the first frame the scale is at 100% but it must to be at 0%!

Can you help me??

[Dan Ebberts]

I think you just need to change the last line to:

[0,0];

Dan