Create an animated GIF: My code plots only the first image

Hi All, I have written some code to create an animated GIF image, but I don't get any update in the image sequence, it only picks up the first image. I don't get any error messages or warnings either and the drawnow sequence works ok.

I have copied below the part of the code that is relevant for this question. I would really appreciate any ideas on this.

Many thanks.

     set(fig1,'Units','normalized','Position',[0 0 1 1]);
     set(fig1,'Units','pixels');
     % Get figure size
     pos = get(gcf, 'Position');
     left=pos(1);
     bottom=pos(2);
     width = pos(3);
     height = pos(4);
     % Preallocate data (for storage frame data)
     mov = zeros(height, width, 1, Imax, 'uint8');

for k=1:Imax

(...)

    set(fig1,'Units','pixels');
    set(fig1,'Position',[left bottom width height]);

    drawnow

    % Get frame as an image
    f = getframe(fig1);

    % Create a colormap for the first frame. For the rest of the frames,
    % use the same colormap
    if k==1
        [mov(:,:,1,k), map] = rgb2ind(f.cdata, 256, 'nodither');
    else
        mov(:,:,1,k) = rgb2ind(f.cdata, map, 'nodither');
    end
 end

imwrite(mov, map, 'animation.gif', 'DelayTime',0, 'LoopCount', inf)

Answer 1

[Sean de Wolski]

It doesn't look like you're actually changing anything in the figure on each iteration. Don't you want to re-plot?

Answer 2

[Saleta]

Hi Sean, I am within the loop. Just didn't show it in the screen. As I said, the update with the drawnow works fine. This is part of the code in the k-loop:

for k=1:Imax subplot(4,4,[2,3,6,7,10,11,14,15]); set(fig1, 'currentaxes', hax);

            if k~=1
                delete(hHoopCentral);
            end
            hHoopCentral=zeros(nSeg,2*Imax);

        for t=1:nSeg

            for m=1:2
                for i=2:4:read1-1
                    hold on
                    if m==1
                        hHoopCentral(t,int16((i+2)/4))=polar(hax,SectionsHoopCentral(t,m).diffStrRelComp(1,:),SectionsHoopCentral(t,m).diffStrRelComp(i,:));
                        %set(hHoopCentral(t,int16((i+2)/4)), 'color', [(read1-1-i)/(read1-1) (read1-1-i)/(read1-1) 1]);
                        set(hHoopCentral(t,int16((i+2)/4)), 'color',[0.75 0.75 1]);
                        set(hHoopCentral(t,int16((i+2)/4)), 'LineWidth',0.5);
                        %Imax=int16((i+2)/4);
                        if int16((i+2)/4)==k
                            set(hHoopCentral(t,int16((i+2)/4)), 'LineWidth',2);
                            set(hHoopCentral(t,int16((i+2)/4)), 'color',[0 0 1]);
                        end
(and so on....)

[Sean de Wolski]

I don't know. I typically don't take the movie approach and instead use the 'writemode append' option (streaming rather than storing).

% Setup
[T, x, y, ang, ~, hh1, hh2, ht, fig] = pendulum_setup();

% Animate and add animation frame to the movie structure
for id = 1:length(T)
    % Update XData and YData
    set(hh1(1), 'XData', T(id)         , 'YData', ang(id, 1))
    set(hh1(2), 'XData', T(id)         , 'YData', ang(id, 2))
    set(hh2(1), 'XData', [0, x(id, 1)] , 'YData', [0, y(id, 1)])
    set(hh2(2), 'XData', x(id, :)      , 'YData', y(id, :))
    set(ht, 'String', sprintf('Time: %0.2f sec', T(id)))

      % Get frame as an indexed image with a map
      I = frame2im(getframe(fig));
      [Ind, map] = rgb2ind(I,256,'nodither');

      % Decide what to do
      if id == 1
          % First iteration, set up GIF properties: loop count and delay time
          imwrite(Ind,map,'animation.gif','gif','LoopCount',Inf,'DelayTime',0);
      else
          % All other iterations, append new frame
          imwrite(Ind,map,'animation.gif','gif','WriteMode','append','DelayTime',0);
      end

end

pendulum_setup is attached.

If it does work, then just go in and modify the pieces you need.