{"id":1974,"date":"2024-02-16T06:43:11","date_gmt":"2024-02-16T11:43:11","guid":{"rendered":"https:\/\/blogs.mathworks.com\/matlab\/?p=1974"},"modified":"2024-02-16T06:43:11","modified_gmt":"2024-02-16T11:43:11","slug":"producing-animated-gifs-from-matlab-flipbook-mini-hack-entries","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/matlab\/2024\/02\/16\/producing-animated-gifs-from-matlab-flipbook-mini-hack-entries\/","title":{"rendered":"Producing animated gifs from MATLAB Flipbook Mini Hack entries"},"content":{"rendered":"
On Valentine's day, the MathWorks linkedIn channel <\/span>posted<\/span><\/a> this animated gif<\/span><\/div>
\"dbc1ee461bf1d391edf5ce670d36353132993b22.gif\"<\/img><\/div>
The obvious question was duly asked \"Where's the MATLAB code for this?\" Turns out, I was uniquely placed to answer this as it <\/span>was one of my entries<\/span><\/a> for the MATLAB Flipbook Mini Hack contest that occurred in late 2023. The full credit, however, has to go to <\/span>Zhaoxu Liu \/ slandarer<\/span><\/a> who wrote the original entry called Particle Heart 2. My version of the code was a lightly edited 'remix' that simply made the heart rotate more quickly, causing it to do a full revolution for every loop of the gif. This idea of remixing was a key feature of the contest which helped make it a lot of fun. Some of the best entries got remixed a lot! <\/span><\/div>
I was at dinner at the time and wasn't able to post a full reply to the questions on LinkedIn so I just posted the link to the <\/span>Minihack entry.<\/span><\/a> Here's the code<\/span><\/div>
function <\/span>drawframe(f)<\/span><\/span><\/div><\/div>
global<\/span> <\/span>theta1 theta2 theta3 heartHdl star1Hdl star2Hdl hpnts sx1 sx2 sy1 sy2<\/span><\/span><\/div><\/div>
if <\/span>f==1<\/span><\/span><\/div><\/div>
% \u6240\u9700\u533f\u540d\u51fd\u6570<\/span><\/span><\/div><\/div>
col1Func=@(n) repmat([255,158,196].\/255,[n,1])+repmat([-39,-81,-56].\/255,[n,1]).*repmat(rand([n,1]),[1,3]);<\/span><\/span><\/div><\/div>
col2Func=@(n) repmat([118,156,216].\/255,[n,1])+repmat([137,99,39].*.1.\/255,[n,1]).*repmat(rand([n,1]),[1,3]);<\/span><\/span><\/div><\/div>
szFunc=@(n) rand([n,1]).*15+8;<\/span><\/span><\/div><\/div>
hold <\/span>on<\/span><\/span><\/div><\/div>
% \u8ba1\u7b97\u7231\u5fc3\u70b9\u4f4d\u7f6e\u5e76\u7ed8\u5236\u7231\u5fc3<\/span><\/span><\/div><\/div>
n=120;<\/span><\/span><\/div><\/div>
x=linspace(-3,3,n); <\/span><\/span><\/div><\/div>
y=linspace(-3,3,n);<\/span><\/span><\/div><\/div>
z=linspace(-3,3,n);<\/span><\/span><\/div><\/div>
[X,Y,Z]=ndgrid(x,y,z);<\/span><\/span><\/div><\/div>
F=((-(X.^2).*(Z.^3)-(9\/80).*(Y.^2).*(Z.^3))+((X.^2)+(9\/4).*(Y.^2)+(Z.^2)-1).^3);<\/span><\/span><\/div><\/div>
FV=isosurface(F,0);<\/span><\/span><\/div><\/div>
hpnts=FV.vertices;<\/span><\/span><\/div><\/div>
hpnts=(hpnts-repmat(mean(hpnts),[size(hpnts,1),1])).*repmat([.75,.7,.7],[size(hpnts,1),1]);<\/span><\/span><\/div><\/div>
hpnts=hpnts+rand(size(hpnts)).*.7;<\/span><\/span><\/div><\/div>
heartHdl=scatter3(hpnts(:,1),hpnts(:,2),hpnts(:,3),<\/span>'.'<\/span>,<\/span>'SizeData'<\/span>,5,<\/span>'CData'<\/span>,col1Func(size(hpnts,1)));<\/span><\/span><\/div><\/div>
% \u8ba1\u7b97\u661f\u661f\u4f4d\u7f6e\u5e76\u7ed8\u5236\u661f\u661f<\/span><\/span><\/div><\/div>
sx1=rand([2e3,1]).*120-60;<\/span><\/span><\/div><\/div>
sy1=rand([2e3,1]).*120-60;<\/span><\/span><\/div><\/div>
sz1=ones(size(sx1)).*-30;<\/span><\/span><\/div><\/div>
star1Hdl=scatter3(sx1,sy1,sz1,<\/span>'.'<\/span>,<\/span>'SizeData'<\/span>,szFunc(length(sx1)),<\/span>'CData'<\/span>,col2Func(size(sx1,1)),<\/span>'LineWidth'<\/span>,1);<\/span><\/span><\/div><\/div>
sx2=rand([2e3,1]).*120-60;<\/span><\/span><\/div><\/div>
sy2=rand([2e3,1]).*120-60;<\/span><\/span><\/div><\/div>
sz2=rand([2e3,1]).*120-20;<\/span><\/span><\/div><\/div>
star2Hdl=scatter3(sx2,sy2,sz2,<\/span>'.'<\/span>,<\/span>'SizeData'<\/span>,szFunc(length(sx2)),<\/span>'CData'<\/span>,[1,1,1]);<\/span><\/span><\/div><\/div>
% \u5750\u6807\u533a\u57df\u4fee\u9970<\/span><\/span><\/div><\/div>
ax=gca;<\/span><\/span><\/div><\/div>
ax.XLim=[-30,30];<\/span><\/span><\/div><\/div>
ax.YLim=[-30,30];<\/span><\/span><\/div><\/div>
ax.ZLim=[-40,30];<\/span><\/span><\/div><\/div>
ax.Projection=<\/span>'perspective'<\/span>;<\/span><\/span><\/div><\/div>
% ax.DataAspectRatio=[1,1,1];<\/span><\/span><\/div><\/div>
view(-42,14);<\/span><\/span><\/div><\/div>
ax.Color=[0,0,0];<\/span><\/span><\/div><\/div>
ax.XColor=<\/span>'none'<\/span>;<\/span><\/span><\/div><\/div>
ax.YColor=<\/span>'none'<\/span>;<\/span><\/span><\/div><\/div>
ax.ZColor=<\/span>'none'<\/span>;<\/span><\/span><\/div><\/div>
set(ax,<\/span>'LooseInset'<\/span>,[0,0,0,0]);<\/span><\/span><\/div><\/div>
set(ax,<\/span>'Position'<\/span>,[-1\/5,-1\/5,1+2\/5,1+2\/5])<\/span><\/span><\/div><\/div>
set(gcf,<\/span>'Color'<\/span>,[0,0,0]);<\/span><\/span><\/div><\/div>
% text(0,0,20,'slandarer','Color','w','HorizontalAlignment','center')<\/span><\/span><\/div><\/div>
% \u65cb\u8f6c\u7231\u5fc3\u548c\u661f\u661f<\/span><\/span><\/div><\/div>
theta1=0;theta2=0;theta3=0;<\/span><\/span><\/div><\/div>
else<\/span><\/span><\/div><\/div>
theta1=theta1-pi\/48;<\/span><\/span><\/div><\/div>
theta2=theta2-0.003;<\/span><\/span><\/div><\/div>
theta3=theta3-0.02;<\/span><\/span><\/div><\/div>
set(heartHdl,<\/span>'XData'<\/span>,hpnts(:,1).*cos(theta1)-hpnts(:,2).*sin(theta1),<\/span>...<\/span><\/span><\/div><\/div>
<\/span>'YData'<\/span>,hpnts(:,1).*sin(theta1)+hpnts(:,2).*cos(theta1))<\/span><\/span><\/div><\/div>
set(star1Hdl,<\/span>'XData'<\/span>,sx1.*cos(theta2)-sy1.*sin(theta2),<\/span>...<\/span><\/span><\/div><\/div>
<\/span>'YData'<\/span>,sx1.*sin(theta2)+sy1.*cos(theta2))<\/span><\/span><\/div><\/div>
set(star2Hdl,<\/span>'XData'<\/span>,sx2.*cos(theta3)-sy2.*sin(theta3),<\/span>...<\/span><\/span><\/div><\/div>
<\/span>'YData'<\/span>,sx2.*sin(theta3)+sy2.*cos(theta3))<\/span><\/span><\/div><\/div>
end<\/span><\/span><\/div><\/div>
end<\/span><\/span><\/div><\/div><\/div>
It's a function that draws a single frame. The software behind the website then called this function in a loop with the frame number going from 1 to 48 and inserted a delay such that the resulting animation would last 2 seconds before starting again. However, if you just had MATLAB then this function only produces a static frame. <\/span><\/div>
drawframe(1);<\/span><\/span><\/div>
<\/div>
<\/div>
<\/div>
<\/div>
<\/div><\/div><\/div><\/div><\/div>
How do you use this to produce the animated gif was the follow up question? I reached out to the team who built the Minihack website and asked them how they did it. How can I reproduce the exact same animated gifs using MATLAB and the <\/span>drawframe()<\/span> functions found on the website? They sent me the code below<\/span><\/div>
function <\/span>animateFrames()<\/span><\/span><\/div><\/div>
animFilename = <\/span>'animation.gif'<\/span>; <\/span>% Output file name<\/span><\/span><\/div><\/div>
<\/span><\/span><\/div><\/div>
firstFrame = true;<\/span><\/span><\/div><\/div>
framesPerSecond = 24;<\/span><\/span><\/div><\/div>
delayTime = 1\/framesPerSecond;<\/span><\/span><\/div><\/div>
<\/span><\/span><\/div><\/div>
<\/span>% Create the gif<\/span><\/span><\/div><\/div>
<\/span>for <\/span>frame = 1:48<\/span><\/span><\/div><\/div>
drawframe(frame);<\/span><\/span><\/div><\/div>
fig = gcf(); <\/span><\/span><\/div><\/div>
fig.Units = <\/span>'pixels'<\/span>;<\/span><\/span><\/div><\/div>
fig.Position(3:4) = [300,300];<\/span><\/span><\/div><\/div>
im = getframe(fig);<\/span><\/span><\/div><\/div>
[A,map] = rgb2ind(im.cdata,256);<\/span><\/span><\/div><\/div>
<\/span><\/span><\/div><\/div>
<\/span>if <\/span>firstFrame<\/span><\/span><\/div><\/div>
firstFrame = false;<\/span><\/span><\/div><\/div>
imwrite(A,map,animFilename, LoopCount=Inf, DelayTime=delayTime);<\/span><\/span><\/div><\/div>
<\/span>else<\/span><\/span><\/div><\/div>
imwrite(A,map,animFilename, WriteMode=<\/span>\"append\"<\/span>, DelayTime=delayTime);<\/span><\/span><\/div><\/div>
<\/span>end<\/span><\/span><\/div><\/div>
<\/span>end<\/span><\/span><\/div><\/div>
end<\/span><\/span><\/div><\/div><\/div>
So, create two m-files, one called <\/span>animateFrames.m<\/span> and the other called <\/span>drawframe.m<\/span>, run <\/span>animateFrames()<\/span><\/div>
animateFrames()<\/span><\/span><\/div><\/div><\/div>
and after a few seconds, you'll have <\/span>animation.gif<\/span> that contains what you are looking for. At this point, I suggest you t<\/span>ake a look at the gallery<\/span><\/a> and find something to animate yourself. These flowers, also from <\/span>Zhaoxu Liu \/ slandarer<\/span><\/a>, perhaps?<\/span><\/div>
\"flowers.gif\"<\/img><\/div>
or how about <\/span>these lanterns<\/span><\/a> by <\/span>Tim<\/span><\/a>?<\/span><\/div>
\"lanterns.gif\"<\/img><\/div>
Even though the competition only lasted 4 weeks, there are over 600 entries for you to play with. Here is a static view of a few more.<\/span><\/div>
\"\"<\/img><\/a><\/div>
The competition had a few restrictions. For example, all animations had exactly 48 frames that would be turned into a 2 second gif. There were also computational time limits and character limits on the <\/span>drawframe()<\/span> function. Now you have the code, you can go crazy and produce animated gifs of whatever complexity you like! <\/span><\/div>\r\n<\/div>