CRACKPATTERN2 Create a (bounded) crack pattern tessellation.

   E = crackPattern2(BOX, POINTS, ALPHA)
   create a crack propagation pattern wit following parameters :
   - pattern is bounded by area BOX which is a polygon.
   - each crack originates from points given in POINTS
   - directions of each crack is given by a [NxM] array ALPHA, where M is
   the number of rays emanating from each seed/
   - a crack stop when it reaches another already created crack. 
   - all cracks stop when they reach the border of the frame, given by box
   (a serie of 4 points).
   The result is a collection of edges, in the form [x1 y1 x2 y2].

   E = crackPattern2(BOX, POINTS, ALPHA, SPEED)
   Also specify speed of propagation of each crack.


   See the result with :
     figure;
     drawEdge(E);

   See also drawEdge

   ---------

   author : David Legland 
   INRA - TPV URPOI - BIA IMASTE
   created the 25/05/2004.

Package: matgeom