how to make a point in matlab AVI video moving in a radom path

I made a 2D AVI animation in Matlab, there are one green dot and one blue dot moving along a line into different directions. But now i want to add into this AVI animation video another dot, which move in a random path together with the other two dots, what should i write codes here now ? attached below is my codes. Thanks very much for your help!

%time steps

      N=20;

%start position of one moving object

      x_pos=10;
      y_pos=10;
      x1_pos=100;
      y1_pos=100;

%speed of the moving object

      speed_x=3;
      speed_y=2;
      speed_x1=-4;
      speed_y1=-2;

%ini white image with size 100 x 150

      image=ones(100,150,3);

%initialization of videowriter

      outputVideo = VideoWriter('test.avi');
      outputVideo.FrameRate = 5; %set frame rate of the image
      open(outputVideo)  

%drawing a moving object on an image plane and creating the video

      for i=1:N

%update states of moving object

      x_pos=x_pos+speed_x;
      y_pos=y_pos+speed_y;
      x1_pos=x1_pos+speed_x1;
      y1_pos=y1_pos+speed_y1;

%draw the measurement on the image using a green point with specific size

      size=4;
      image((x_pos-size/2):(x_pos+size/2),(y_pos-size/2):(y_pos+size/2),1)=0;
      image((x_pos-size/2):(x_pos+size/2),(y_pos-size/2):(y_pos+size/2),3)=0;
      image((x1_pos-size/2):(x1_pos+size/2),(y1_pos-size/2):(y1_pos+size/2),2)=0;
      image((x1_pos-size/2):(y1_pos+size/2),(y1_pos-size/2):(y1_pos+size/2),1)=0;

%give the image to the video writer object

      writeVideo(outputVideo,image)

Answer 1

[Image Analyst]

See my attached demo that you can adapt to do that.

[Jing Huang]

@Image Analyst Thanks for your help.