Hi guys! I know I can bounce when the sprite hit boundary but how can I bounce when my sprite hit a wall for example? What formula can I use for it?

http://scratch.mit.edu/projects/12004820/

You will just me messing with the X parameters instead of the Y

You can make the wall part of the backdrop, or a sprite.

Its not that simple… I need a way to bounce accord to the angle like a mirror reflexion of a laser!

see in “dl.dropboxusercontent.com/u/16702799/images/bounce.png”

My wall is a sprite already, but I want my another sprite bounce when collide with wall sprite, I know theres a calculation but I dont remember !

If you are moving in a direction, set the new direction ito 180-direction

If you are using Y velocity and X velocity you do it like this http://scratch.mit.edu/projects/13152873/

Thanks I will try !

Are you drawing the path, or just having an object bounce?

Just an object fired by a cannon which sometime will bounce against a wall, Im using direction.
Thanks!

Locomule wrote:

One problem with bouncing is when your sprite hits two walls at the same time in a corner. Here is a solution to that.

Do you mean for the ball to bust right out of the box? It does.

Do you want to assume perfect bounciness (no loss of speed)?

It was fine on my pc. I made the ball speed ajustable. If it leaves the box, restart it and slow it down 1 speed. Eventually it should run fine. The point is that the method works. I could have made the wall thicker but I wanted to prove that the system works on its own.

Likewise, if you start it and the ball stays inside, try speeding it up. I made it deafault to 6 which is half as fast as my pc will run it correctly.

ps. Most Scratch problems do not have a bulletproof solution. If I increase the ball speed too much, I will have to increase the wall thickness, add more check loops, or maybe use a different method, like using 4 sprites for the walls. Or adding a feeler sprites. Or backing the ball up after contact, etc. Even the most stable method may have to be replaced or altered as your project grows.