%%%%%%%%%%%%%%%%%%%%% Intractive Tesselation with Mouse %%%%%%%%%%%%%%%%%%%
%
% MTESS
% Usage: MTESS(p,q,r,e,T0,)
%
% Inputs:  p,q,r  - real numbers with 1/p +1/q +1/r < 1 
%                   see SCHWARTZ for the interpretation of p,q,r
%          e      - optional erasure parameter, see below 
%          T0     -  initial triangle
%
% Output:  word - the sequence of reflections created by the interactive 
%          tesellation 
%          T - final triangle   
%          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,T] = mtess(p,q,r,e,T0);

% initializations

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

if (nargin < 4) e ='BF'; end;
erase = [sum(e == 'B') sum(e == 'F')];

if (nargin >= 5)
     T = T0;
   else 
     T = schwartz(p,q,r);
   end; 

% plotting colours

vc1 = 'r';
vc2 = 'y';
vc3 = 'g';
cc  = 'w';
ec  = 'k';
tricol = 'w';


% graphics and menu setup 
tritype = [inttostr(p) '-' inttostr(q) '-' inttostr(r)]; 

Q      = 27; 
Terase = 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([ tritype ' 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, 'Esc: Quit');

plottri(T,tricol);
plotvert(T,vc1,vc2,vc3);
plotcent(T, 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(T,ec);  
      A = T(1);  B = T(2);  C = T(3); 
      wa = sameside([B C A],z);
      wb = sameside([C A B],z);       
      wc = sameside([A B C],z);
      h = 0;
      if (wa < h) side = 'a'; h = wa; end;
      if (wb < h) side = 'b'; h = wb; end;
      if (wc < h) side = 'c'; h = wc; end;
      if h < 0 

         T2 = trirefl(T,side);
         if (btn == right) 
            side = upcase(side); 
            end;
         if (btn == left) 
            plottri(T2,tricol); 
            plotvert(T2,vc1,vc2,vc3); 
            end;
         T = T2;
         word = [word side];     
         end;
      plotcent(T,cc);
      end;   
   if (btn == Terase)   
      plottri(T,ec);
      end;
  end;

if erase(2) clf; end;