gif of sphere with changing radius in Matlab - matlab

Question

I wish to generate a .gif file of a sphere that grows in size(radius) over time based on a specified function relating radius and time. I'm having some trouble with how to formulate the animation.
Here is what I have so far:
%% Parameters
dt = 0.05;
time = 0:dt:1;
radius = 1
%% generate sphere
[X, Y, Z] = sphere(25);
X=X*radius;
Y=Y*radius;
Z=Z*radius;
mySphere = surf(X,Y,Z, 'FaceLighting','gouraud');
axis equal
shading interp
mySphere.FaceAlpha = 0.3
view([61 15])
colormap bone
hold on
%% generate gif
filename = 'Sizechange.gif';
for n = 1:20
radius = 1 + time(n)
im = frame2im(getframe(1));
[imind,cm] = rgb2ind(im,256);
if n == 1;
imwrite(imind,cm,filename,'gif', 'Loopcount',inf,'DelayTime',dt);
else
imwrite(imind,cm,filename,'gif','WriteMode','append','DelayTime',dt);
end
end
Here I am trying to get it to go from radius 1 to radius 2 in steps of 0.05.
When I run this however, the gif stays still at 1 and there is no animation.
Any help would be greatly appreciated.

Answer 1

As #cris-luengo said, you should redraw your sphere for each iteration on the radius.
%% Parameters
dt = 0.05;
time = 0:dt:1;
radius = 1 ;
%% generate sphere
[X, Y, Z] = sphere(25);
X=X*radius;
Y=Y*radius;
Z=Z*radius;
%figure;
%mySphere = surf(X,Y,Z, 'FaceLighting','gouraud');
% axis equal
% shading interp
% mySphere.FaceAlpha = 0.3;
% view([61 15])
% colormap bone
% hold on
%% generate gif
filename = 'Sizechange.gif';
figure;
for n = 1:20
radius = 1+ time(n);
%====================================================
X=X*radius;
Y=Y*radius;
Z=Z*radius;
mySphere = surf(X,Y,Z, 'FaceLighting','gouraud');
axis equal
shading interp
mySphere.FaceAlpha = 0.3;
view([61 15])
colormap bone
%====================================================
im = frame2im(getframe(1));
[imind,cm] = rgb2ind(im,256);
if n == 1
imwrite(imind,cm,filename,'gif', 'Loopcount',inf,'DelayTime',dt);
else
imwrite(imind,cm,filename,'gif','WriteMode','append','DelayTime',dt);
end
end