On Pset4 "bounce" Can anyone please help me in bouncing the ball at angles after it touches the window edges and paddle?! I mean is what all the math computation involved in it?? a pseudocode highly recommended... Thanks in advance

1 Answer 1


It's not too bad on the math side. In summary, you just reverse the values of the x and y velocity when it contacts the object.

For instance, if the ball hits the right edge of the window.

the x-velocity variable (controlling up and down motion) would remain unchanged while the y-velocity variable would be reversed;

//if collision between ball and right edge of window
   yvelocity = -yvelocity

In the case of the paddle or a brick, you would modify the xvelocity

//if collision between ball and brick
  xvelocity = -xvelocity
  yvelocity = -yvelocity

The part that takes a little adjustment on your part is to figure out how to modify the xvelocity just slightly every time the ball contacts the paddle so that there is a bit of randomization and that the user doesn't get stuck in an endless loop with a ball that won't hit certain spots. You can try using a random number as a multipler and adding a constant to it.

  //if collision between ball and paddle
      xvelocity = (-xvelocity * drand48()) + some constant number
      yvelocity = -yvelocity

The formula is really personal preference and can be adjusted as you see fit to make the game more or less difficult and unpredictable.

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