This is a RhinoScript that I wrote about a few months ago in: http://crtl-i.com/blog/2008/12/diffuse-noise/

It will take a curve and diffuse it into many curves according to a few parameters:
devRate: deviation rate
vecLenMax: maximum length of a particle
vecLenMin: minimum length of a particle
noParticle: number of total particles

If vecLenMax and vecLenMin are the same, all the particles will have the same length. 

—

Option Explicit

Call Diffuse()

 

Sub Diffuse()

 

Dim devRate : devRate = 0.01

Dim vecLenMax : vecLenMax = 1

Dim vecLenMin : vecLenMin = 3

Dim noParticle : noParticle = 100

 

Dim aCrvs : aCrvs = Rhino.GetObjects(“Select Curves”, 4)

 

Dim i,n

Dim aPts()

Dim crvDom, crvParam, crvLen

Randomize

For i = 0 To UBound(aCrvs)

 

n = 0

Dim strCrv : strCrv = aCrvs(i)

 

crvDom = Rhino.CurveDomain(strCrv)

crvLen = Rhino.CurveLength(strCrv)

 

Rhino.EnableRedraw False

 

Do Until n = noParticle

 

crvParam = (RN(0.00, 1.00)) * (crvDom(1))

 

ReDim Preserve aPts(n)

aPts(n) = Rhino.EvaluateCurve(strCrv, crvParam)

Dim devPt : devPt = aPts(n)

Dim devX : devX = crvLen * devRate * RN(-1,1) + devPt(0)

Dim devY : devY = crvLen * devRate * RN(-1,1) + devPt(1)

Dim devZ : devZ = crvLen * devRate * RN(-1,1) + devPt(2)

Dim devPt2 : devPt2 = Array(devX, devY, devZ)

Dim rndPt : rndPt = Array(RN(-1,1), RN(-1,1), RN(-1,1))

Dim rndPt2 : rndPt2 = Rhino.PointAdd(devPt2, rndPt)

 

If n >= 1 Then

Dim vecDir : vecDir = Rhino.AddLine(devPt2, rndPt2)

Dim vecLen : vecLen = RN(vecLenMin, vecLenMax)

Dim Xform : Xform = Rhino.XformScale(devPt2, vecLen)

Rhino.TransformObject vecDir, Xform, True

End If

 

n = n + 1

 

Loop

 

Rhino.EnableRedraw True

Next

End Sub

 

Function RN (nMin, nMax)

RN = Null

Randomize

RN = (nMax – nMin) * Rnd + nMin

End Function