How to stop the forces acting on a body in box2d

Question

I am using box2d on the iphone to create a game. I have a body that is effected by gravity to move down and not right or left. It will get hit by another body and will then be moving right or left. I then have a reset button which moves the body back to its starting point. The only problem is that it is still moving right or left. How can I counteract the forces that a ball is already traveling? How can I get rid of this right and left movement when I reset my game?

Solution

Box2d automatically clears the forces each simulation step. I think you are just changing your body's position when resetting, but not its velocity. Add this code to your reset method:

body->SetLinearVelocity(b2Vec2(0,0));
body->SetAngularVelocity(0);

Comments

[TomSawyer]

I've tried this way but doesn't work when two object close to each other stackoverflow.com/questions/39716111/…

[Andrew]

@TomSawyer: they probably collide after you reset the velocities and that causes their velocity to change again

[TomSawyer]

I think resetting the velocity make one object stand still. it's impossible to collide to the other. Anyway to make sure one object has been stopped?