%%%%%%%%%%%%%%%%%%%%% Interactive Tesselation with Mouse %%%%%%%%%%%%%%%%%%%
%
% QMTESS
% Usage: QMTESS(s,t,u,v,h,e,Qu0)
%
% Inputs:  s,t,u,v  - real numbers with 1/s + 1/t + 1/u + 1/v < 2 
%                    see QSCHWARTZ for the interpretation of s,t,u,v
%          h        - sidelength
%          e        - optional erasure parameter, see below 
%          Qu0      - initial quadrilateral
%
% Output:  word - the sequence of reflections created by the interactive 
%          tesellation 
%          Qu - final quadrilateral   
%          e is a string composed of the following options
%               'B'   erase at beginning start with new boundary circle
%               'b'   do not erase at beginning 
%               'F'   clear graphics at end 
%               'f'   do not clear graphics at end  
%               default is 'BF'


function [word,Qu] = qmtess(s,t,u,v,h,e,Qu0);

% initializations

I = sqrt(-1);
word = [];

if (nargin < 6) e ='BF'; end;
erase = [sum(e == 'B') sum(e == 'F')];

if (nargin >= 7)
     Qu = Qu0;
   else 
      Qu = qschwartz1(s,t,u,v,h);
   end; 

% plotting colours

vc1 = 'r';
vc2 = 'y';
vc3 = 'g';
vc4 = 'b';
cc  = 'w';
ec  = 'k';
quadcol = 'w';


% graphics and menu setup 
quadtype = [inttostr(s) '-' inttostr(t) '-' inttostr(u)' '-' inttostr(v)]; 

Q      = abs('Q'); 
Qerase = abs('E');
left   = 1;
right  = 3;

mbx = -1.5;         mby =  .8;  
lx = mbx;         ly = mby-.15;
rx = mbx;         ry = ly -.25;
kx = mbx;         ky = ry -.3;
ex = mbx;         ey = ky-.15;
qx = mbx;         qy = ey-.15;

% screen drawing
if erase(1) boundary([ quadtype ' Tiling'],'','w'); end;
text(mbx,mby, 'Mouse Buttons');
text(lx,ly, 'Left:');
text(lx,ly-.1, '  reflect & draw');
text(rx,ry, 'Right:');
text(rx,ry-.1, '  reflect only');
text(kx,ky-.1, 'Keys');
text(ex,ey-.1, 'E: Erase');
text(qx,qy-.1, 'Q: Quit');

plotpoly(Qu,quadcol);
plotvertq(Qu,vc1,vc2,vc3,vc4);
plotcent(Qu, cc);

% main loop
btn = 0;                        
while (btn ~= Q)                        
   [x,y,btn] = ginputsab(1);
   btn = rem(rem(btn,256)+256,256);
   btn = abs(upcase(setstr(btn)));    

   z = x+y*I; 
   if (abs(z) < 1.5)&(sum(btn == [left right]))  % check if mouse button pressed 
      plotcent(Qu,ec);  
      S = Qu(1);  T = Qu(2);  U = Qu(3); V = Qu(4);
      wa = sameside([S T U],z);
      wb = sameside([T U V],z);       
      wc = sameside([U V S],z);
      wd = sameside([V S T],z);
            
      k = 0;
      if (wa < k) side = 'a'; k = wa; end;
      if (wb < k) side = 'b'; k = wb; end;
      if (wc < k) side = 'c'; k = wc; end;
      if (wd < k) side = 'd'; k = wd; end;
      if k < 0 

         Qu2 = polyrefl(Qu,side);
         if (btn == right) 
            side = upcase(side); 
            end;
         if (btn == left) 
            plotpoly(Qu2,quadcol); 
            plotvertq(Qu2,vc1,vc2,vc3,vc4); 
            end;
         Qu = Qu2;
         word = [word side];     
         end;
      plotcent(Qu,cc);
      end;   
      if (btn == Qerase)   
%      plotpoly(Qu,ec);
      end;
  end;

if erase(2) clf; end;