This is a fractal Worley noise (F2-F1).
Inspired by the book "Texturing and modeling a procedural approach" (Ebert, MusGrave, Peachey,Perlin,Worley) ISBN 1-55860-848-6
Values for DistanceType :
1: Euclidian
2: Manhattan
3: Chessboard
4: Minkowski (r = 0.5)
5: Superquadratic
This is a freeware, you can use it for commercial and non commercial purpose.
Developped by David Lanier 3D
Plugins & shaders development company
www.dl3d.com.