This example shows how to animate a triangle looping around the inside of a circle by updating the data properties of the triangle.

Plot the circle and set the axis limits so that the data units are the same in both directions.

theta = linspace(-pi,pi); xc = cos(theta); yc = -sin(theta); plot(xc,yc); axisequal

Use theareafunction to draw a flat triangle. Then, change the value of one of the triangle vertices using the (x,y) coordinates of the circle. Change the value in a loop to create an animation. Use adrawnowordrawnow limitratecommand to display the updates after each iteration.drawnow limitrateis fastest, but it might not draw every frame on the screen.

xt = [-1 0 1 -1]; yt = [0 0 0 0]; holdont = area(xt,yt);% initial flat triangleholdoffforj = 1:length(theta)-10 xt(2) = xc(j);% determine new vertex valueyt(2) = yc(j); t.XData = xt;%更新数据属性t.YData = yt; drawnowlimitrate% display updatesend

The animation shows the triangle looping around the inside of the circle.