Plugin/ Effect that allows forward movement in winding pattern

[nessl28139642]

I want to move a light forward in z direction, away from screen. This is needed in order to drive Trapcode Tao and achieve t a moving tunnel effects. I could do a curvy motion pattern for the light with keyframes, but since I want to synch the movement to soundkeys a manual curly arrangment doesn't seem to be efficient. That's why I right ask for an effect that can be applied to an object and makes it possible to inch it forward windingly. 

[Mylenium]

Parent the light to Null, animate the Null's rotation and position.

Mylenium

[nessl28139642]

Yea, thank you, but at this point I wasn't even sure how I animate a position, that suits my demands. I figured it's menagable with expressions that can be linked directly with the position of the light:

a = 80;
f = 0.2;
x = a*Math.sin(time*f*Math.PI)+thisComp.width/2;
y = 0;
z = time*5-thisComp.height/2;
[x,y,z]

However here comes the next barrier: I want to adjust the speed of the sine wave according to the rythme. But it seems like if any of these parameters do not change linearly, the sine wave loses it's shape. So things like:

z = thisComp.layer("Keys").effect("Sound Keys")("Output 1");

lead to jagged motion. I might ask this as a new questions since u seem busy.  

[nessl28139642]

By the way: Output1 delivers rising values dependent on the rythme. No back and forth. But still...

[Mylenium]

http://www.motionscript.com/articles/speed-control.html

Mylenium

[Rick Gerard · Accepted solution]

I'm not exactly sure what kind of a path you are trying to achieve or what parts of the path you are trying to modify using sound keys but here are a couple of ideas. 

• Null Z move - moves in a straight line in Z space.
• Null Y is tied to the movement of NullZ in the Z space but the Y anchor point value is animated using a linear or an ease expression based on Audio Amplitude.
• The rotation of Null Y is tied to Audio Amplitude by n ease expression 

This setup can give you a spiral path for Null Y that changes size based on Audio Amplitude. If you use Dan Ebberts' Frequency control expression at the bottom of the page that he applies to time remapping and applied that to the Rotation of Null Y, you would get something like this:

I applied echo to the shape layer parented to the Y rotation null so you could see the spiral path with the diameter changing because of the audio levels.

Here are the expressions:

// for Null Y Anchor Point:
x = value[0];
t = thisComp.layer("Audio Amplitude").effect("Both Channels")("Slider");
y = ease(t, 0, 50, 0, 400);
z = - thisComp.layer("Null Z").transform.position[2];
[x, y, z]

// for Null Y Z rotation

spd = thisComp.layer("Audio Amplitude").effect("Both Channels")("Slider");
mult = 3;
n = spd.numKeys;
if (n > 0 && spd.key(1).time < time){
  accum = spd.key(1).value*(spd.key(1).time - inPoint);
  for (i = 2; i <= n; i++){
    if (spd.key(i).time > time) break;
    k1 = spd.key(i-1);
    k2 = spd.key(i);
    accum += (k1.value + k2.value)*(k2.time - k1.time)/2;
  }
  accum += (spd.value + spd.key(i-1).value)*(time - spd.key(i-1).time)/2;
}else{
  accum = spd.value*(time - inPoint);
}
value + accum*mult

You could use the same technique to change how far the Z value changes based on audio by modifying the accumulation expression for the Z value. The biggest trick is in using more than one null, then parenting your light to that null. Shift + parent will snap any layer to the same position and orientation as the parent so it's really easy to get this set up.