%% NAST2D_STREAK_MOVIE reads an NAST2D streakline file and creates a movie.
%
%  The streaklines are shown evolving in time.
%
  clear
%
%  input data
%
  icase = input ( ' Enter case: 1=dam, 2=wave, 3=drop ' ) 

  if ( icase == 1 )
    B = load ('dam.str');
    xmin = 0;
    xmax = 10;
    ymin = 0;
    ymax = 5;
  elseif ( icase == 2 )
    B = load ('wave.str');
    xmin = 0;
    xmax = 40;
    ymin = 0;
    ymax = 10;
  elseif ( icase == 3 )
    B = load ( 'drop.str' );
    xmin = 0;
    xmax = 8;
    ymin = 0;
    ymax = 5;
  end

  [m,n] = size ( B )
%
%  use all the data? or skip some values?
%
  skip = input ( ' Enter SKIP to use every SKIP-th value of the data ' ) 
%
%  Determine the number of frames and the size of each
%
  frames = 0;
  for i = 1 : 1 : m
    if ( B(i,2) == -1 & B(i,3) == -1 & B(i,4) == -1 )
      frames = frames + 1
      count(frames) = 0;
    else
      count(frames) = count(frames) + 1; 
    end
  end
%
%  Render and save each frame of the movie into Mv.
%
  index = 0;
  for j = 1:1:frames
    index = index + 1;
    for i=1:1:count(j)/skip
      index = index + skip;
      x(i) = B(index,1);
      y(i) = B(index,2);
    end
    plot ( x, y, '.' );
    clear x;
    clear y;

    set ( gca, 'Xlim', [xmin xmax] );
    set ( gca, 'Ylim', [ymin ymax] );
    xlabel ( 'x', 'FontName', 'Helvetica', 'FontWeight', 'bold', ...
      'FontSize', 16 );
    ylabel ( 'y', 'FontName', 'Helvetica', 'FontWeight', 'bold', 'FontSize', ...
      16, 'Rotation', 0 );
    title ( 'Streaklines', 'FontName', 'Helvetica', 'FontWeight', 'bold', ...
      'FontSize', 16 );

    Mv(j) = getframe;

  end
%
%  Play the frames
%
%  NREPS = number of repetitions of the movie.
%  FPS = frames per second.
%
  nreps = 4;
  fps = 10;
  movie ( Mv, nreps, fps );