function [sys, x0, str, ts] = udg(t, x, u, varargin)
% UDG  User-defined graphics.
% Plot data u in MATLAB figure.
% u is assumed to be Nx2; first column real-part, second column imag-part.
% Can also pass additional parameters to plot function

switch varargin{1}
    case 3
        sys = [];  % mdlOutput - unused
    case 2
        sys = mdlUpdate(t, x, u, varargin{:});
    case 0
        [sys, x0, str, ts] = mdlInitializeSizes;
    case 9
        sys=mdlTerminate;
    otherwise
        feval(varargin{:});
end


% -----------------------------------------------------------
function [sys, x0, str, ts] = mdlInitializeSizes

blk = get_param(gcb, 'parent');

sizes = simsizes;
sizes.NumInputs      = -1;
sizes.NumOutputs     =  0;
sizes.NumSampleTimes =  1;
sys = simsizes(sizes);
x0  = [];           % states
str = '';           % state ordering strings
ts  = [-1 1];       % inherited sample time, fixed in minor steps

% initialize block data
bd = get_param(blk, 'userdata');
bd.firstcall = true;
bd.figTag = blk;
bd.graphicsName = get_param(blk, 'graphicsName');
bd.plotFcnHandle = str2func(bd.graphicsName);
set_param(blk, 'userdata', bd);


% ------------------------------------------------------------
function sys = mdlUpdate(t, x, u, flag, params)

% Faster implementation of: blk=gcb;
cs   = get_param(0, 'CurrentSystem');
cb   = get_param(cs, 'CurrentBlock');
sfcn = [cs '/' cb];
blk  = get_param(sfcn, 'parent');
sys  = [];

bd = get_param(blk, 'userdata');

% Form complex vector
u_complex = u(:, 1) + j*u(:, 2);

% Extra parameters
other_params = params;
other_params_exist = ~isempty(other_params);

% Need to check for figure every update (faster way?)
bd.fig = findobj('type', 'figure', 'tag', bd.figTag);
figExists = ~isempty(bd.fig);

if ~figExists && ~bd.firstcall
    % Return if user closed figure during simulation.
    return
end

if ~figExists
    % figure is not open
    
    bd.fig = figure;
    set(bd.fig, 'tag', bd.figTag);
    set(bd.fig, 'render', 'zbuffer');
    set(bd.fig, 'numbertitle', 'off');
    set(bd.fig, 'name', bd.figTag);
    bd.axes = [];
    bd.firstcall = true;
    
else
    if bd.firstcall
        figure(bd.fig);
    end
end

% Call graphics function
if other_params_exist
     feval(bd.plotFcnHandle, u_complex, bd.axes, bd.firstcall, other_params{:});
else
     feval(bd.plotFcnHandle, u_complex, bd.axes, bd.firstcall)
end

if bd.firstcall
    % get axes handles
    [bd.axes, bd.multiple_axes] = get_axes_handles(bd.fig);
end

bd.firstcall = false;

set_param(blk, 'userdata', bd);

% ---------------------------------------------------------------
function sys = mdlTerminate
sys = [];

%--------------------------------------------------------------------------
function [haxes, multi] = get_axes_handles(fig);
% returns axes handles
% if there is only one axes, axes is a handle
% if more, axes is a structure of handles, with fieldnames corresponding to
% axes tags.
% to fix: return only children which are axes
% multi: true if more than one axes
c = findobj(fig, 'type', 'axes');
multi = (length(c)>1);
if ~multi
    haxes = c;
else
    t = get(c, 'tag');
    h = num2cell(c);
    x = [t(:).'; h(:).'];
    haxes = struct(x{:});
end