function spm_dem_reach_movie(DEM)
% creates a movie of the trajectory of a two-joint arm
% FORMAT spm_dem_reach_movie(DEM)
%
% DEM - DEM structure from reaching simulations
%__________________________________________________________________________
% Copyright (C) 2008 Wellcome Trust Centre for Neuroimaging

% Karl Friston
% $Id: spm_dem_reach_movie.m 3901 2010-05-27 16:14:36Z karl $


% evaluate positions (target)
%--------------------------------------------------------------------------
try
    v = DEM.pU.v{2};
    C = v(3,:);                                  % target color
    T = [v(1,end); v(2,end)];                    % target location
    C = C - min(C);
    C = C/max(C);
end

% evaluate positions (motor plant)
%--------------------------------------------------------------------------
x    = DEM.pU.x{1};                              % angular position
J    = spm_dem_reach_x2J(x);                     % joint location
J{2} = J{1} + J{2};                              % finger location
fin  = imread('finger.jpg');
N    = size(x,2);

% movie
%--------------------------------------------------------------------------
s     = 1/4;
for i = 1:N

    cla
    axis image ij
    hold on

    % arm
    %----------------------------------------------------------------------
    imagesc(([-2 0] + 1/3)*s + J{2}(1,i),([-1 0] + 1/2)*s + J{2}(2,i),fin);
    plot([0 J{1}(1,i)],[0 J{1}(2,i)],'color',[1 .8 .7]*.8)
    plot([J{1}(1,i) J{2}(1,i)],[J{1}(2,i) J{2}(2,i)],'color',[1 .8 .7]*.8)

    % target (T) or scribe (moving trajectory)
    %----------------------------------------------------------------------
    try
        plot(T(1),T(2),'.','MarkerSize',32,'color',[C(i) (1 - C(i)) 0])
    catch
        x  = J{2}(1,1:i) + ([1:i] - i)/N;
        y  = J{2}(2,1:i);
        plot(x,y,'color',[1 1 1]*.8,'Linewidth',4)
    end
    axis([-0.5 1.5 0 2])
    hold off
    drawnow

    % save
    %----------------------------------------------------------------------
    M(i) = getframe(gca);

end

% set ButtonDownFcn
%--------------------------------------------------------------------------
h = findobj(gca,'type','image');
set(h(1),'Userdata',{M,16})
set(h(1),'ButtonDownFcn','spm_DEM_ButtonDownFcn')