MODULE PZFractDim EXPORTS Main;

(* Given a curve segment, generates a length vs. scale plot. *)
(* Last edited on 1998-09-15 00:17:34 by stolfi *)

IMPORT 
  PZTypes, PZProc, LR3, 
  Wr, FileRd, FileWr, OSError, Thread, Stdio, Fmt, Math, ParseParams, Process;
FROM LR3 IMPORT Dist;
FROM Stdio IMPORT stderr;   

<* FATAL Wr.Failure, Thread.Alerted , OSError.E *>

TYPE
  Options = RECORD
      inFile: TEXT;     (* Input float chain file (without ".flc") *)
      outFile: TEXT;    (* Otput file name (minus ".plt" *)
    END;

PROCEDURE Main() =      
  BEGIN 
    WITH 
      o = GetOptions(),
      fc = PZLR3Chain.Read(FileRd.Open(o.inFile & ".flc")),
      chain = fc.chain^,
      wr = FileWr.Open(o.inFile & ".plt")
    DO 
      PlotFractalDistance(wr, chain);
      Wr.Close(wr);
    END;
  END Main;

PROCEDURE GetOptions(): Options =
  VAR o: Options;
  BEGIN
    WITH
      pp = NEW(ParseParams.T).init(stderr)
    DO
      TRY
        pp.getKeyword("-inFile");
        o.inFile := pp.getNext();

        pp.getKeyword("-outFile");
        o.outFile := pp.getNext();

        pp.finish();                                       
      EXCEPT                                                            
      | ParseParams.Error =>                                              
          Wr.PutText(stderr, "Usage: PZFilter \\\n");
          Wr.PutText(stderr, "  -inFile NAME -outFile NAME \n");
        Process.Exit(1);
      END;
    END;
    RETURN o
  END  GetOptions;

PROCEDURE PlotFractalDistance(
    wr: Wr.T; 
    READONLY p: PZLR3Chain.T;
  )=
  VAR step: LONGREAL := 1.0d0;
      s, T, ta, tb: LONG;
      pa, pb: LR3.T;
      ka, kb: CARDINAL;
  BEGIN
    WITH 
      n = NUMBER(p),
      t = NEW(ARRAY OF LONG, n)^,
      v = NEW(PZLR3Chain.T, n)^,
      
    DO 
      T := LinearLengths(p, t);
      REPEAT 
        WITH
          m = CEILING(T/step
          q = NEW(PZLR3Chain.T, n)^
        DO
          ka := 0; ta := 0.0d0; pa := p[0];
          s := 0.0d0;
          LOOP
            FindNextSample(t, p, ka, ta, pa, step, kb, tb, pb);
            IF kb >= n-1 THEN EXIT END;
            s := s + LR3.Dist(pa, pb);
            ka := kb; ta := tb; pa := pb
          END;
          s := s + LR3.Dist(pa, p[n-1]);
          Wr.PutText(wr, Fmt.LongReal(step) & " " & Fmt.LongReal(s) & "\n");
          step := 2.0d0*step;
        END
      END UNTIL step >= T/2.0d0;
    END; 
  END PlotFractalDistance;
  
PROCEDURE FindNextSample(
    READONLY p: PZLR3Chain.T;
    READONLY t: ARRAY OF LONG;
    ka: NAT;
    ta: LONG;
    pa: LR3.T;
    step: LONG;
    VAR kb: NAT;
    VAR tb: LONG;
    VAR pb: LONG;
  ) =
  (*
    Computes a new time "tb" ahead of "ta", and the corresponding point "pb" on 
    the open polygonal chain "p[0..n-1]" with cumulative lengths
    "t[0..n-1]".  The new point "pb" is chosen so that 
    "LR3.Dist(pa, pb) = step".  Also returns "kb" such that the
    chosen time "tb" is between "t[kb]" and "t[kb+1]". Returns
    "kb = n-1" if there is no such point.*)
  VAR klo, khi: NAT;
      tlo, thi: LONG;
  BEGIN
    WITH
      n = NUMBER(p)
    DO
      tlo := ta; thi := ta + step;
      klo := ka; khi := ka; WHILE khi < n-1 AND t[khi+1] < thi DO INC(khi) END;
      
    END~
    
    
  END FindNextSample

BEGIN
  Main()
END DimFractal.





BEGIN
  Main()
END PZFractDim.