Box2D Forums

Hi All, Heres the issue - I extend B2ContactListener so I can change the UserData on objects that have collisions. I create my custom contact listener class and use the SetContactListener( ) function to apply it to the world. However, it soon became clear that I wasn't getting any contacts so.... I trace back to the b2World class where the BeginContact function is being called and it seems its not getting called there either! As you can see I have traces in all blocks of code and none are getting called. Any help here would be appreciated! Thanks Dan

Heres my code:

//setting up new listener ( from main game class )

var contact_listener : PopoutContactListener = new PopoutContactListener();
_world.SetContactListener( contact_listener ) ;

// overrides begincontact (copied from PopoutContactListener that extends b2ContactListener )

override public function BeginContact(contact:b2Contact):void {
trace('BeginContact call ') ;
var fixtureA:b2Fixture=contact.GetFixtureA();
var fixtureB:b2Fixture=contact.GetFixtureB();
var data : Object ;

if (fixtureB.IsSensor()) {
data = getUserData( fixtureB.GetBody() ) ;
data.status = 'hit'
fixtureB.GetBody().SetUserData( 'hit' );
}
if (fixtureA.IsSensor()) {
data = getUserData( fixtureA.GetBody() ) ;
data.status = 'hit'
fixtureA.GetBody().SetUserData( 'hit' );
}
}

protected function getUserData( body : b2Body ) : Object
{
trace('getUserData call ', body ) ;
return body.GetUserData() ;
}

// from the b2World class
public function BeginContact(c:int, a:b2Fixture, b:b2Fixture):void {
trace('begin contact');
if(m_contactListener){
m_contactListener.BeginContact(new b2Contact(c, a, b));
}
}

You have to set reportBeginContact, reportEndContact, Etc. on the fixtures you want contact events from. This is because there's some overhead when exiting Alchemy and calling the function, so it only does it for fixtures with those flags set.

Thanks very much for this, ill try it at the first oppurtunity! Dan