我在 iphone 上使用 box2d 来创建游戏.我有一个受重力影响的身体向下移动而不是向右或向左移动.它会被另一个物体击中，然后向右或向左移动.然后我有一个重置按钮，可以将身体移回起点.唯一的问题是它仍在向右或向左移动.我怎样才能抵消球已经在移动的力?重置游戏时如何消除这种左右移动?

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?

推荐答案

Box2d 自动清除每个模拟步骤的力.我认为你只是在重置时改变了身体的位置，而不是它的速度.将此代码添加到您的重置方法中:

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);