ansaurus

Question

After Effect - Triangle Wave (JavaScript)

Answer 1

+1 A:

Seems to have already been answered

http://stackoverflow.com/questions/1073606/is-there-a-one-line-function-that-generates-a-triangle-wave

Peter Bailey 2010-04-09 15:11:05

Yeah I saw that but After Effects doesn't seem to recognise abs function, maybe it's not implemented in AE?

PJ Palomaki 2010-04-09 15:22:40

What about `Math.abs()`? If not, you can always write your own (if AE lets you define functions)

Peter Bailey 2010-04-09 16:01:20

Correct! Math.abs() did the trick, silly me.Thanks Peter!

PJ Palomaki 2010-04-09 16:31:20

Answer 2

+1 A:

An easy way to get a triangle wave from here would be to subtract m/2 and take the absolute value. Alternatively, use f = m - abs(i % (2*m) - m).

John Feminella 2010-04-09 15:12:52

See above, AE doesn't seem to allow abs... Am I missing out something here?

PJ Palomaki 2010-04-09 15:23:22

Use `Math.abs()`. It's in the Javascript pulldown, I think.

John Feminella 2010-04-09 16:08:07

Thanks John! That's it, got it working.Much appreciated.

PJ Palomaki 2010-04-09 16:31:57

Just a (hopefully) final question, how can I get the triangle wave to give me negative values as well? So oscillating between i.e. 16 and -16?The line is currently like this: x = m - Math.abs(i % (2*m) - m);

PJ Palomaki 2010-04-09 16:38:07

What's it oscillating between right now?

John Feminella 2010-04-09 17:09:26

Whis this code it oscillates between 0 and 8:freq = 20;nd amplitude = 8; m = amplitude;i = time*freq;m - Math.abs(i % (2*m) - m);How can I get it to go to -8?Thanks!

PJ Palomaki 2010-04-11 11:43:22

Make it `2 * Math.abs(...) - m`.

John Feminella 2010-04-11 12:23:23

Hmm... still doesn't give negative values.. now oscillates between 0 and 16. Code: `2 * Math.abs(i % (2*m) - m);`

PJ Palomaki 2010-04-11 15:38:07

You didn't write what I said. Keep the part in the `abs` the same as in post, but make it `2 * Math.abs(...) - m`.

John Feminella 2010-04-11 16:01:22

Ahhh... my bad! So finally this code works:`2 * Math.abs(i % (2*m) - m) - m;`Thanks John, very much appreciated!

PJ Palomaki 2010-04-11 16:14:36

Erhm... and how would I get the wave to start from negative value instead of a positive?

PJ Palomaki 2010-04-11 16:26:59

Shift `i` accordingly (e.g. by making `i +/- [something]`).

John Feminella 2010-04-11 21:00:32

Thanks again John!

PJ Palomaki 2010-04-12 08:24:13

ansaurus

tags:

views:

answers:

After Effect - Triangle Wave (JavaScript)

related questions