动态改变接触过滤器-Box2d-Changingcontactfilteronthefly

9  

b2Filter filter;

for ( b2Fixture* f = body->GetFixtureList(); f; f = f->GetNext() ) {
    f->GetFilterData( &filter );
    filter.categoryBits = ...;
    filter.maskBits = ...;
    filter.groupIndex = ...;
    f->SetFilterData( &filter );
}

Obviously this would change the filter settings for all fixtures on a body - if you want to be more selective you will have to be able to tell which fixture is which somehow. Eg. if you know it's the only circle fixture you could just look at the type of the fixture to decide, otherwise you would have to make use of the fixture's user data I guess.

显然，这将更改主体上所有装置的过滤器设置——如果您想要更有选择性，您必须能够以某种方式知道哪个装置是哪个装置。如。如果你知道这是唯一一个圆夹具，你可以只看夹具的类型来决定，否则你将不得不使用夹具的用户数据。

0  

You can iterate over all bodies in the b2World. On each body you can iterate over it's fixture and change it's filter. To identify your bodies you can use userData.

可以遍历b2World中的所有主体。在每个主体上，您可以遍历它的fixture并更改它的过滤器。要识别您的身体，您可以使用userData。

0  

The answer from iforce2d might be obsolete. I got the following code working properly with box2d v2.2.1, cocos2D v2.0.0 using Xcode v4.5.2 (here I assume I have a pointer to a b2Body named 'body' with only one fixture, i.e., I don't iterate over all fixtures on the body):

来自iforce2d的答案可能已经过时了。我使用Xcode v4.5.2使用box2d v2.2.1、cocos2D v2.0.0正确运行了以下代码(在这里，我假设我有一个指向一个名为“body”的b2Body的指针，只有一个fixture，即“body”。，我不会对身体上所有的固定装置进行迭代):

b2Fixture *fix = body->GetFixtureList();
b2Filter filter = fix->GetFilterData();   
filter.groupIndex = -1*kPlayerGroupIndex; 
fix->SetFilterData(filter);

In the above code I prevent 'body' from colliding with my player body which also has the same groupIndex value, i.e., -1*kPlayerGroupIndex, where kPlayerGroupIndex is a positive integer constant. Any bodies with this negative groupIndex never collide with one another. You could also update the categoryBits or maskBits accordingly to prevent collisions.

在上面的代码中，我阻止了“body”与我的player body发生冲突，它也具有相同的groupIndex值，即。-1*kPlayerGroupIndex，其中kPlayerGroupIndex为正整数常量。任何具有这个负群指数的物体都不会相互碰撞。您还可以相应地更新类别位或maskBits，以防止冲突。

GetFilterData(&filter) and SetFilterData(&filter) returned errors for me given the version numbers I quoted above.

GetFilterData(&filter)和SetFilterData(&filter)返回了我上面引用的版本号的错误。