function scopeani()
%Plots a slow-speed simulated scope screen to illustrate the effect
%of proper or improper triggering.  Use buttons to select the triggering to
%animate.  Push the stop button on the figure to get the menu back; quit
%from the quit button on the menu

%C. Sullivan, 7/01  Charles.R.Sullivan@dartmouth.edu

choice=0;
while choice ~= 5,

choice=menu('Select Triggering','None','y = trigger level','+ slope crossing','- slope crossing','quit');

if choice==5, return, end

f = 1.105;
sweeprate = 0.5;
sweeps = 50;
triglevel = 0.5;
points = 100;

anifun(f,sweeprate,sweeps,choice,triglevel,points);

end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% End of Main, start of functions (just one)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

function M=anifun(f,sweeprate,sweeps,trig,triglevel,anilen)
%This function, though not scopani, offers partial support for...
%OPTIONAL OUTPUT M=xlineani(....)
%The animation can then be run, more smoothly, with 
%>>movie(M)

displayrate = 20;
figure(1)
%____________________
    % The STOP button--from odeplot
    %h = findobj(f,'Tag','stop');
    %if isempty(h)
      ud.stop = 0;
      pos = get(0,'DefaultUicontrolPosition');
      pos(1) = pos(1) - 15;
      pos(2) = pos(2) - 15;
      str = 'ud=get(gcf,''UserData''); ud.stop=1; set(gcf,''UserData'',ud);';
      stophandle=uicontrol( ...
          'Style','push', ...
          'String','Stop', ...
          'Position',pos, ...
          'Callback',str, ...
          'Tag','stop');
    %else
    %  set(h,'Visible','on');            % make sure it's visible
    %  if ishold
    %    oud = get(f,'UserData');
    %    ud.stop = oud.stop;             % don't change old ud.stop status
    %  else
    %    ud.stop = 0;
    %  end
    %end
    set(gcf,'UserData',ud);
%____________________


%plot "beam", set up axes, etc.
hx=plot(0,0,'wo','markersize',8,'markerFaceColor','g');
axis([0 1/sweeprate -1.5 1.5])
whitebg(gcf,'k')
set(gcf,'DoubleBuffer','on')
hold on
ylabel('V')
xlabel('t')  
told = 0;


for sweep = 1:sweeps
   
%Get some data ready to plot
t=linspace(told,told+1/sweeprate,anilen);
y = sin(2*pi*f*t);

set(hx,'xdata',0)  %Set beam to left

%if trig == 1
%do nothing special--just go ahead.

if trig ==6
%old method--no longer used.
   %find first place it gets close
   [minabs,imin] = min(abs(y-triglevel));
   typabs = abs(y(imin+1)-triglevel);
   close = abs(y-triglevel)<typabs;
   it = find(close);
   it = it(1);
   
   for ti = 2:it
      set(hx,'ydata',y(ti))
      pause(1/displayrate)
   end
   
   told = t(it);
   t=linspace(told,told+1/sweeprate,anilen);
   y = sin(2*pi*f*t);
  
end
if trig ==2
   %find first place it crosses
   y0=y(1);
   cross = -1 == sign(y0-triglevel)*sign(y-triglevel);
   it = find(cross);
   it = it(1);
   
   for ti = 2:it
      set(hx,'ydata',y(ti))
      pause(1/displayrate)
   end
   
   told = t(it);
   t=linspace(told,told+1/sweeprate,anilen);
   y = sin(2*pi*f*t);
  
end

if trig == 3
   %find first place it crosses - to +
   y0=y(1);
   side = sign(y-triglevel);
   cross = diff(side);
   pcross = cross > 0;
   it = find(pcross);
   it = it(1);
   
   for ti = 2:it
      set(hx,'ydata',y(ti))
      pause(1/displayrate)
   end
   
   told = t(it);
   t=linspace(told,told+1/sweeprate,anilen);
   y = sin(2*pi*f*t);
  
end

if trig == 4
   %find first place it crosses + to -
   y0=y(1);
   side = sign(y-triglevel);
   cross = diff(side);
   ncross = cross < 0;
   it = find(ncross);
   it = it(1);
   
   for ti = 2:it
      set(hx,'ydata',y(ti))
      pause(1/displayrate)
   end
   
   told = t(it);
   t=linspace(told,told+1/sweeprate,anilen);
   y = sin(2*pi*f*t);
  
end



tplot = linspace(0,1/sweeprate,anilen);

%set up initial plot
h=plot(tplot(1),y(1),'g');
 
%Loop to generate animation SWEEP!!!!!!!
for ti=1:anilen
   set(h,'Ydata',y(1:ti),'Xdata',tplot(1:ti)); 
   set(hx,'ydata',y(ti),'Xdata',tplot(ti));
   %Show and/or collect plots
   if(nargout > 0)
      M(ti)=getframe;
   else
      pause(1/displayrate)
      oud = get(gcf,'UserData');
      if oud.stop ==1, break, end
    end
 end
 
 if oud.stop ==1, break, end
 told=t(length(t));
 %hold on
end
hold off