Alternate between two values x-times per second.

[Dan Ebberts]

I think this will do it:

zVal1 = 500;
zVal2 = 1000;
freq = 50;

phase = Math.floor(time*freq);
z = phase%2 ? zVal2 : zVal1;
[value[0],value[1],z]

Dan

[Andy Rider]

Thanks for replying so quickly Dan I appreciate your help!

I tried the expression (which I almost understand lol). Unfortunatly I don’t think After Effects works the way I thought it might.

I’m trying to create an audio wave form using Particular releasing static particles.

I used audio key frames to effect the emitter’s height y-axis and a null to animate it across the x-axis. I thought if i used enough particles and moved them back and forth the z-axis fast enough I would be able to give the waveform some depth

Unfortunately due to the comp frame rate the expression rounds the position off to either one of the two values and does not show evidence of movement between frames.

Cheers

Andy

[Filip Vandueren]

In trapcode Particular V2 (just released) you can set the Emitters position to ‘precise’,
which is to say that it will recalculate the position of the emitter for every particle that’s spawned.

Unless you specify this, the maximum timing resolution of Particular is 1/10th of a frame. (the default, and only option in V1)

So it’s not a limitation of After Effects

[Andy Rider]

Cheers for your help Filip.

I should have been less vague in my first post as the expression Dan kindly wrote works per frame.

1/10th of a frame might just be good enough until I can afford Particular 2. I would need an expression that works like a wiggle frequency but without the randomness and in-between values i.e. alternate between value “x” and value “y” 250 times a second.

Does any one have any idea if this is possible as i think the waveform could look quite cool with some work?

Thanks

Andy