% Program 2.8
% R-RTR-RTR 
% Position analysis 
% Creating a movie

clear; clc; close all
AB = 0.14; AC = 0.06; AE = 0.25; CD = 0.15; 
xA = 0; yA = 0; xC = 0 ; yC = AC; xE = 0; yE = -AE; 

axis([-0.3 0.3 -0.3 0.3]); % create axis

M = moviein(6); % allocate/initialize the matrix to have 6 frames

set(gca,'NextPlot','replacechildren')
% prevents the plot function from resetting the axis shaping  to axis 
% normal each time it is called

incr = 0;

for phi=pi/3:pi/3:2*pi,

xB = AB*cos(phi); yB = AB*sin(phi); 
eqnD1 = '( xDsol - xC )^2 + ( yDsol - yC )^2 = CD^2 ';
eqnD2 = '( yB - yC ) / ( xB - xC ) = ( yDsol - yC ) / ( xDsol - xC )';
solD = solve(eqnD1, eqnD2, 'xDsol, yDsol');
xDpositions = eval(solD.xDsol); yDpositions = eval(solD.yDsol);
xD1 = xDpositions(1); xD2 = xDpositions(2);
yD1 = yDpositions(1); yD2 = yDpositions(2);
if (phi>=0 && phi<=pi/2)||(phi >= 3*pi/2 && phi<=2*pi)
   if xD1 <= xC xD = xD1; yD=yD1; else xD = xD2; yD=yD2; end
   else
   if xD1 >= xC xD = xD1; yD=yD1; else xD = xD2; yD=yD2; end
end

plot([xA,xB],[yA,yB],'r-o',[xB,xD],[yB,yD],'b-o',[xD,xE],[yD,yE],'g-o'),...
text(xA,yA,'  A'), text(xB,yB,'  B'), text(xC,yC,'  C'),...
text(xD,yD,'  D'), text(xE,yE,'  E')

incr = incr + 1;

M(:,incr) = getframe; % record the movie

end % end for

% movie(M,5) % run the movie 5 times