The right way to make animations with Matlab

This page explains how to make animations with Matlab. The idea is to create a figure, get the associated object and update these objects properties. The page presents a step by step guide. If you are familiar with Matlab, go straight to the example code.

Create a figure

First create a figure, here we will just draw a point at coordinates (10,10) in a new figure. First create a new figure:

figure

Force the axis between 0 and 20 on each axis:

axis ([0,20,0,20])

Keep the previous content in the figure:

hold on

Draw a point and get properties

Draw the point, note that we will get the plot properties in the object h:

h = plot (10,10,'o');

Your figure should look something like:

When drawing the point, we get the object properties (h). We can now access the object properties with the following command:

>> get (h)
    AlignVertexCenters: 'off'
            Annotation: [1×1 matlab.graphics.eventdata.Annotation]
          BeingDeleted: 'off'
            BusyAction: 'queue'
         ButtonDownFcn: ''
              Children: [0×0 GraphicsPlaceholder]
              Clipping: 'on'
                 Color: [0.9290 0.6940 0.1250]
             CreateFcn: ''
             DeleteFcn: ''
           DisplayName: ''
      HandleVisibility: 'on'
               HitTest: 'on'
         Interruptible: 'on'
              LineJoin: 'round'
             LineStyle: 'none'
             LineWidth: 0.5000
                Marker: 'o'
       MarkerEdgeColor: 'auto'
       MarkerFaceColor: 'none'
         MarkerIndices: 1
            MarkerSize: 6
                Parent: [1×1 Axes]
         PickableParts: 'visible'
              Selected: 'off'
    SelectionHighlight: 'on'
                   Tag: ''
                  Type: 'line'
         UIContextMenu: [0×0 GraphicsPlaceholder]
              UserData: []
               Visible: 'on'
                 XData: 10
             XDataMode: 'manual'
           XDataSource: ''
                 YData: 10
           YDataSource: ''
                 ZData: [1×0 double]
           ZDataSource: ''

The previous command display all the properties of the point. Most usefull properties are :

XData : the X-coordinate of the point
YData : the Y-coordinate of the point
Color : the color of the point
Marker : the style of the marker
MarkerSize : the size of the marker

Updating properties

To create an animation, we will not redraw the point, we will update its properties with the command set. First, let's change the point marker:

set (h, 'Marker', 'x')

The marker should be changed to a cross:

We can also change the marker color:

set (h, 'Color', 'r')

Display should be updated:

The most important attribute to create animation is to update the points coordinates. We can change several attribute with the same command. The following command update the X and Y coordinates of the point:

set (h, 'XData',3, 'YData', 5)

Here, the point has moved to coordinates (3,5):

Animate in a loop

The following code draw a vertical line and animate the line to turn around the point (0,0):

close all;
clear all;

%% Initialization of the figure

% Draw the line and get line properties
l = line ([0,0] , [0,1]);
% Set axis 
axis ([-2,2,-2,2]);

%% Main loop

% Loop on the line angle (from 0 radians to 2pi radians
for a=0:0.01:2*pi
    % Update the line coordinates
    set (l, 'XData',[0,sin(a)], 'YData',[0, cos(a)] );

    % Refresh the figure
    drawnow;
end

Here is the result :

The right way to make animations with Matlab

Create a figure

Draw a point and get properties

Updating properties

Animate in a loop

See also