Collision Problem (Square 2d)

Hello there, i am trying to write some code that plots a square moving along a line with a certain velocity when the centre of the squares coordinates get within a certain tolerance the direction of the velocity becomes negative and so it 'bounces' off the wall. My code is below but the constraints in terms of direction don't seem to be working any insight would be greatly appreciated. Best Regards

fps = 20; 
dt = 1/fps; 

tmax = 10; 
t = 0; 
theta = 0;
dtheta = 1/20;

p = transpose([20,20,1]); 
v = transpose([50,25,1]); 

Vobj = transpose([2, -2, 1; 2,2,1; -2, 2, 1; -2, -2, 1]);

while t < tmax
    x = p + t*v;
    if x(1)<= 5 || x(1) >= 95
      v(1)=-v(1);
    elseif x(2)<= 5 || x(2) >= 95
      v(2)=-v(2);
    end
    p = x;

      % Transformations
      T = [1,0,p(1);0,1,p(2);0,0,1];
      S = [1+0.2*sin(2*t),0,0; 0,1+0.2*sin(2*t),0;0,0,1];
      R = [cos(theta),sin(theta),0 ;-sin(theta),cos(theta),0;0,0,1];

      % Application of Transformations
      V = R*S*T*Vobj;

      fill(V(1,:),V(2,:),'r')

      hold on
      axis([0,100,0,100])
      hold off
      shg;
      pause(0.3);

      % Updates
      t = t + dt;
      theta = theta + dtheta;
  end

[aliyah islam]

Did you end up figuring this problem out? If so have you still got the matlab code for it, as i have a similar problem to solve. Thanks

Answer 1

[madhan ravi]

   fps = 20; 
      dt = 1/fps; 
      tmax = 10; 
      t = 0;
      x =[20,20,1]; 
      v = [50,25,1]; 
      ctr=1;
      while t < tmax
          p(ctr,:) = x + t*v;
          if p(1) < 5 || p(1) > 95 || p(2) < 5 || p(2) > 95
              p(ctr,:) = x + t*(-v);
          else
              p(ctr,:) = x + t*v;
          end
          plot(p(1),p(2),'o')
          hold on
          axis([0,100,0,100])
          hold off
          pause(1);  
          t = t + dt;
      end

[madhan ravi]

use counter to solve the problem

[Jake Simmonds]

This still has the same issue as my above code once it enters the tolerance it just disappears

[Jake Simmonds]

It's a matter of changing the direction the plot goes after it is in the critical zone so to speak.