Expression help (please)

[John Dickinson]

This is one way:

wigfreq = 5; //wiggle frequency
wigangle = 45; //wiggle amplitude
wignoise = 3; //octaves of noise
just = wiggle(wigfreq, wigangle, wignoise);
[position[0], just[1]] //will wiggle just on Y.

JD

John Dickinson
Motionworks
http://www.motionworks.com.au

[Guy]

excellent, thanks. One more question?

How can I limit the number that this expression returns to be 0 to 100?

thanks!!!

[John Dickinson]

There is probably a very specific way that someone more versed in expressions could suggest but one way to limit the returned value is to use a simple math modifier. Here I’ve halved the return value for the Y property by adding “/2”

[position[0], just[1]/2]

John Dickinson
Motionworks
http://www.motionworks.com.au

[Filip Vandueren]

Theoretically if you Wiggle a property that has a start-value of 50, with an amplitude of 50
you should get values of 50, plus or minus 50, so that would be 0-100

But in reality, you’ll find the value will sometimes drop beneath 0 and over 100, particularly if you use more than one ‘noise-octave’.

Again in theory, this:

wigfreq = 5; //wiggle frequency
wigangle = 45; //wiggle amplitude
wignoise = 3; //octaves of noise
just = wiggle(wigfreq, wigangle, wignoise, 0.5);

(the multiplier defaults to 0.5 I believe, but you can set it explicitly as a 4th parameter in wiggle)

would give values plus or minus 78.75
->
45 + 45*0.5 + 45*(0.5*0.5) = 78.75

so to have a range of 0-100 you should set the default (keyframed) value to 50,
and use an amplitude of about 28.57.

because:

28.57 + 28.57*0.5 +28.57*(0.5*0.5) = 50

In reality the chance that you get values that are near 0 or near 100 will be very low, because this only happens if the 3 random numbers from each of the octaves are all equal to 1 or equal to 0.
So perhaps it’s best to use only one octave, the wiggle will be smoother, but also you will get more extreme values.

an alternative is to set the multiplier to 1, and amp to 16.66 (50/3 octaves)
wiggle(wigfreq, wigangle, wignoise, 1);

you’ll get 16.66 + 16.66 + 16.66 = 50

this will give a harsher more aggressive wiggle

If this multiplier & octaves stuff is a bit confusing, do a google on “Perlin noise”.
In essence it’s the same as ‘complexity’ in the fractal noise plug-in.