"Tom Melly" <tom### [at] tomandlucouk> wrote in message
news:3cc4283d@news.povray.org...

BTW here's the code (which is based on some lightning code I wrote ages ago):

#macro Cylinder_Object(CStart, CVec, CWidth, CAng, CLev)
  #local cylLen  = 4 * ((rand(myRand) + 0.5)/CLev);
  #local cylTran = transform{
    rotate x*(2 * CAng * rand(myRand) - CAng)
    rotate y*(360 * rand(myRand))
    Reorient_Trans(y * 1, CVec)
    translate CStart
  }
  #declare segPosB = vtransform(y * cylLen, cylTran);
  #declare segVec = segPosB - CStart;
  cylinder{
    0, y * cylLen, CWidth, 1
    transform{cylTran}
  }
#end

#macro Make_Tree(TArraySize, TSeed, TBWidth, THt, TCutoff, TBranch, TAng, TLevs)

  #declare PosArray = array[TArraySize];
  #declare VecArray = array[TArraySize];
  #declare WidArray = array[TArraySize];
  #declare LevArray = array[TArraySize];
  #declare PosArray[0] = <0,0,0>;
  #declare VecArray[0] = <0,1,0>;
  #declare WidArray[0] = TBWidth;
  #declare LevArray[0] = 1;

  #declare checkCount = -1;
  #declare highCount  = 0;
  #declare myRand     = seed(TSeed);

  #declare Tree =
  blob{
    threshold 0.5
    #while (checkCount < highCount)

      #declare checkCount = checkCount + 1;
      #declare segPosA    = PosArray[checkCount];
      #declare segVec     = VecArray[checkCount];
      #declare segWidth   = WidArray[checkCount];
      #declare segLev     = LevArray[checkCount];
      #declare segPosB    = segPosA;
      #declare CarryOn    = true;

      #while(vlength(segPosB) < THt & segWidth > 0.05 & CarryOn)
        #declare segPosA = segPosB;
        Cylinder_Object(segPosA, segVec, segWidth, TAng, segLev)

        #declare randNum = rand(myRand);
        #if(randNum > 1 - ((segLev^2)/500))
          #declare CarryOn = false;
        #end
        #if (randNum < (TBranch/(segLev^0.25)) & segLev < TLevs &
vlength(segPosB) > TCutoff)
          #declare segWidth  = segWidth * 0.75;
          #declare highCount = highCount + 1;

          #declare PosArray[highCount] = segPosB;
          #declare VecArray[highCount] = segVec;
          #declare WidArray[highCount] = segWidth * 0.95;
          #declare LevArray[highCount] = segLev + 1;
        #end
      #end
    #end
  }
#end

//#macro Make_Tree(TArraySize, TSeed, TBWidth, THt, TCutoff, TBranch, TAng,
TLevs)
Make_Tree(50000, 1868, 5, 40, 8, 0.45, 30, 9)
object{Tree pigment{Gray50}}

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