Animation Techniques

You can use four basic techniques to create animations in MATLAB^®.

Technique	Description	Example
Update data in a loop.	Update the properties of a graphics object and display the updates on the screen in a loop. This technique is useful for creating animations when most of the plot remains the same. For example, set the XData and YData properties of a Scatter object in a loop to create an animation effect.	Create Animation by Updating Data in Loop
Apply matrix transformations.	Apply transforms to objects. This technique is useful when you want change the position and orientation of a group of objects together. Group the graphics objects as children under a transform object. Create the transform object using the hgtransform function. Set the Matrix property of the transform object to adjust the position of all its children.	Create Animation Using Matrix Transformation
Create an animated GIF file.	Update a figure and capture the frames of an animated GIF using the exportgraphics function in a loop.	Create Animated GIF File
Create a movie.	Update a figure and capture the frames of a movie using the getframe function in a loop. This technique is useful for complex animations that do not draw quickly in real time or when you want to store an animation to replay it. Use the movie function to play the movie.	Create and Play Movie

Create Animation by Updating Data in Loop

Create an animation of a marker moving along a line.

• Plot a sine wave. Then plot a marker and save it as the variable mkr so you can access its properties later.

• Use the xlim, ylim, and zlim functions to set the limits of each axis. Setting the limits disables the automatic axis limits calculation, which can cause flicker and affect the performance of the animation.

• Create a for-loop that updates the coordinates of the marker. Change the XData and YData properties of the Scatter object (mkr) at each iteration to move the marker along the line.

• Call the drawnow command at the end each loop iteration to update the figure display.

x = linspace(0,10,500);
y = sin(x);

% Plot a line and a marker
plot(x,y)
hold on
mkr = scatter(NaN,NaN,[],"red","filled");
hold off
xlim([0 10])
ylim([-1 1])
zlim([-1 1])

% Move the marker along the line
for i = 1:length(x)
    mkr.XData = x(i);
    mkr.YData = y(i);
    drawnow
end

Create Animation Using Matrix Transformation

An efficient way to animate a plot is to apply a transformation matrix to one or more objects rather than iterating over all the points. The transformations you can use include translation, rotation, and scaling. You can also define your own transformation matrix.

Create an animation of a sphere rotating it 2π radians on an arbitrary axis.

• Create the coordinates of a sphere using the sphere function.

• Create a Transform object named grp. Then plot the sphere as a Surface object by calling the surf function and specifying the parent object as grp.

• Display the axes grid lines and show the plot box in a 3-D view.

• Create a for-loop that steps through 300 equally spaced angle values from 0 to 2π, rotating the sphere by a small angle at every iteration. Use the makehgtform function to create the transformation matrix for each small angle of rotation. Then set the Matrix property of grp to perform the rotation.

• Call the drawnow command at the end of each loop iteration to update the figure display.

% Create the coordinates of a sphere
figure
ax = axes;
[x,y,z] = sphere(270);

% Create transform object and plot the sphere
grp = hgtransform(Parent=ax);
s = surf(ax,x,y,z,z,Parent=grp,EdgeColor="none");

% Display grid lines and show the plot box in 3-D
grid on
view(3)
axis vis3d
axis tight manual

% Rotate the sphere by small angles in a loop
for ang = linspace(0,2*pi,300)
   tm = makehgtform("axisrotate",[1,1,1],ang);
   grp.Matrix = tm;
   drawnow
end

Create Animated GIF File

Create an animated GIF file of a marker moving along a parabola.

• Plot a parabola with one marker.

• Create a for-loop that changes the location of the marker at every iteration.

• At the end of each loop iteration, capture the figure as a frame of an animated GIF file using the exportgraphics function. When you specify the Append=true name-value argument, exportgraphics captures the current frame and appends it to the specified GIF file.

• The resulting parabola.gif file is saved to your current folder.

% Plot a parabola and a marker
x = -10:0.5:10;
y = x.^2;
p = plot(x,y,"-o",MarkerFaceColor="red");

% Move the marker along the parabola and capture frames in a loop
for i=1:41
    p.MarkerIndices = i;
    exportgraphics(gca,"parabola.gif",Append=true)
end

Create and Play Movie

Create a movie of a surface plot changing shape by using the getframe function in a loop. The getframe function captures the movie frames in an array of structures, and you use the movie function to play the movie.

• Plot the coordinates of the peaks function as a surface using the surf function and save the Surface objects as the variable s.

• Position the plot box tightly around surface and freeze the axes limits using the axis tight manual command.

• Create an array of 40 structures named F to contain the animation frames.

• Create a for-loop that changes the shape of the surface at every iteration.

• At the end of each loop iteration, update the figure using the drawnow command and capture a movie frame using the getframe function.

• The resulting movie is saved as the structure array F.

% Plot a surface
Z = peaks;
s = surf(Z);
axis tight manual

% Change the shape of the surface and capture frames
loops = 40;
F(loops) = struct('cdata',[],'colormap',[]);
for j = 1:loops
    Zframe = sin(j*pi/10)*Z;
    s.ZData = Zframe;
    drawnow
    F(j) = getframe(gcf);
end

Play the movie two times.

fig = figure;
movie(fig,F,2)