import pylab
from faceBeamInteraction import *
import numpy as np

def beamTrace(beams, faces, borders, borderLimits):
   # trace beam and all it reflections and refractions on faces
   # for beams and faces structure description see faceBeamInteraction.m
   # border similar to faces cell array which enclose the beam
   # i.e. it does not leave the polygon consisting of border faces

   intensityThreshold = 1e-2 # intensity of the weakest beam we still trace
   processedBeams = []

   nBeams = len(beams)
   if nBeams == 0:
      # no more beam to trace
      return processedBeams

   # trace each beam in beams cell array
   intenseEnoughBeams = []
   intenseBeamsCounter = 0
   for beam in beams:
      [isFaceHit, hitPosition, hitDistance, newBeams] =\
       faceBeamInteraction(beam, faces)
      if (isFaceHit):
         beam.hitPosition = hitPosition
         # remove beams which are to weak to trace
	 nNewBeams = len(newBeams)
	 for newBeam in newBeams:
	    if newBeam.intensity >= intensityThreshold:
	       intenseBeamsCounter += 1
	       intenseEnoughBeams.append(newBeam)
	 #try:
	 newProcessedBeams = \
	     beamTrace(intenseEnoughBeams, faces, borders, borderLimits)
	 #except ValueError:
	  #  break
	 processedBeams.append(newProcessedBeams)
      else:
	 # beam does not hit face but it should stop at borders
	 beam.face = None
	 [isFaceHit, hitPosition, hitDistance, newBeams] = \
	  faceBeamInteraction(beam, borders)
	 if not isFaceHit:
	    print 'borders are badly defined, the beam misses them'
	    return False
	 beam.hitPosition = hitPosition
   processedBeams.append(newBeams)
   return processedBeams