plot_fwselect(celldata, idx, flag)

function plot_fwselect(celldata, idx, flag)
% PLOT_FWSELECT - plot selected freeway cell.
%
% Call:   plot_fwselect(celldata, idx)
%
% Parameters:
%             celldata - array of freeway cell structures;
%             idx      - index to 'celldata' array;
%             flag     - specifies if the cell is selected or unselected;
%
% Returns:   none.
%
% Last modified:   11/11/2006.

%
% Alex Kurzhanskiy   <[e-mail]>
%

K = 2;
N = size(celldata, 2);  % number of cells

if (N < 1) | (idx < 1) | (idx > N)
  return;
end

ih = ishold;

if celldata(idx).PMstart <= celldata(idx).PMend  % direction: from LEFT to RIGHT
  dr = 1;
else  % direction: from RIGHT to LEFT
  dr = -1;
end

if flag
  C1 = 'y';
  C2 = 0.5 * [1 1 1];
else
  C1 = 'w';
  C2 = 'k';
end

xylim = axis;
Xml   = [celldata(idx).PMstart celldata(idx).PMstart celldata(idx).PMend celldata(idx).PMend celldata(idx).PMstart];
Yml   = [(-dr)*ceil(celldata(idx).lanes) 0 0 (-dr)*ceil(celldata(idx).lanes) (-dr)*ceil(celldata(idx).lanes)];
Yfr   = [xylim(3) xylim(4) xylim(4) xylim(3) xylim(3)];
fill(Xml, Yfr, C1);
hold on;
plot(Xml, Yfr, C1);
fill(Xml, Yml, C2);
plot(Xml, Yml, C1);

Yr  = [Yml(1) Yml(1) (Yml(1)-K*dr) (Yml(1)-K*dr) Yml(1)];
wdt = min(get_cell_lengths(celldata))/8;

if ~isempty(celldata(idx).ORname)  % plot on-ramp
  w = wdt * celldata(idx).ORlanes;
  x = celldata(idx).PMstart;
  if dr > 0
    Xor = [(x+wdt) (x+wdt+w) (x+w) x (x+wdt)];
  else
    Xor = [(x-wdt) (x-wdt-w) (x-w) x (x-wdt)];
  end
  fill(Xor, Yr, 'b');
  plot(Xor, Yr, 'b');
end

if ~isempty(celldata(idx).FRname)  % plot off-ramp
  w = wdt * celldata(idx).FRlanes;
  x = celldata(idx).PMend;
  if dr > 0
    Xfr = [(x-wdt) (x-wdt-w) (x-w) x (x-wdt)];
  else
    Xfr = [(x+wdt) (x+wdt+w) (x+w) x (x+wdt)];
  end
  fill(Xfr, Yr, 'g');
  plot(Xfr, Yr, 'g');
end

plot([xylim(1:2) xylim(2) xylim(1) xylim(1)], ...
     [xylim(3) xylim(3) xylim(4) xylim(4) xylim(3)], 'k');

axis(xylim);

xlabel('Post Mile');
h = gca;
set(h, 'YTick', []);

if ih == 0
  hold off;
end

return;