我从本教程中下载了 Ray Wenderlich 的简单接触监听器:http://www.raywenderlich.com/606/how-to-use-box2d-for-just-collision-detection-with-cocos2d-iphone
目前我正在使用下面的代码,它几乎是我的 CCLayer 中 Ray 的自定义 b2ContactListener 的实现。但问题是,一次碰撞有多个回调。
有人可以告诉我如何制作,以便碰撞只会触发一次,直到两个物体未接触然后再次修饰吗?
这是我当前使用的代码:
std::vector<b2Body *>toDestroy;
std::vector<MyContact>::iterator pos;
for(pos = _contactListener->_contacts.begin(); pos != _contactListener->_contacts.end(); ++pos) {
MyContact contact = *pos;
// Get the box2d bodies for each object
b2Body *bodyA = contact.fixtureA->GetBody();
b2Body *bodyB = contact.fixtureB->GetBody();
if (bodyA->GetUserData() != NULL && bodyB->GetUserData() != NULL) {
CCSprite *spriteA = (CCSprite *) bodyA->GetUserData();
CCSprite *spriteB = (CCSprite *) bodyB->GetUserData();
if ((spriteA.tag == 1 && spriteB.tag == 2) || (spriteA.tag == 2 && spriteB.tag == 1)) {
NSLog(@"tag 1 hit tag 2");
}
谢谢!
编辑1:
if ((hasDetectedCollision == NO) && ( (spriteA.tag == 1 && spriteB.tag == 2) || (spriteA.tag == 2 && spriteB.tag == 1) ) ) {
hasDetectedCollision = YES;
NSLog(@"tag 1 hit tag 2");
[self doSomethingWhenCollisionHappens];
}
- (void)doSomethingWhenCollisionHappens {
//here you might want to remove an object because of a collision
//or maybe change the color of the objects that collided
//I can't provide more details of what you might want
//to do without seeing more of your code
//but when you are ready to start receiving collision updates again
//set hasDetectedCollision to NO again
[yesLabel setString:[NSString stringWithFormat:@"Yes: %d", yesNumber++]];
hasDetectedCollision = NO;
}
然后在我的 init 方法中:
hasDetectedCollision = NO;
新编辑:
if (!hasDetectedCollision && ((spriteA.tag == 1 && spriteB.tag == 4) || (spriteA.tag == 4 && spriteB.tag == 1))) {
hasDetectedCollision = YES;
[yesLabel setString:[NSString stringWithFormat:@"Yes:%d", yesInt++]];
NSLog(@"tag 1 hit tag 4");
}
最佳答案
我不熟悉 Box2d,但是根据您在问题中所描述的内容,这应该可以帮助您:
在你的.h中:
@interface foo : FooBar {
BOOL hasDetectedCollision;
}
在你的.m中:
- (void)viewDidLoad {
hasDetectedCollision = NO;
}
然后简单地替换
if ((spriteA.tag == 1 && spriteB.tag == 2) || (spriteA.tag == 2 && spriteB.tag == 1)) {
NSLog(@"tag 1 hit tag 2");
}
与
if ((hasDetectedCollision == NO) && ( (spriteA.tag == 1 && spriteB.tag == 2) || (spriteA.tag == 2 && spriteB.tag == 1) ) ) {
hasDetectedCollision = YES;
NSLog(@"tag 1 hit tag 2");
[self doSomethingWhenCollisionHappens];
}
然后:
- (void)doSomethingWhenCollisionHappens {
//here you might want to remove an object because of a collision
//or maybe change the color of the objects that collided
//I can't provide more details of what you might want
//to do without seeing more of your code
//but when you are ready to start receiving collision updates again
//set hasDetectedCollision to NO again
hasDetectedCollision = NO;
}
然后,每当您完成检测到碰撞时想做的任何事情时,将 hasDetectedCollision 设置回 no,然后就可以重新开始。
编辑:
std::vector<b2Body *>toDestroy;
std::vector<MyContact>::iterator pos;
for(pos = _contactListener->_contacts.begin(); pos != _contactListener->_contacts.end(); ++pos) {
MyContact contact = *pos;
// Get the box2d bodies for each object
b2Body *bodyA = contact.fixtureA->GetBody();
b2Body *bodyB = contact.fixtureB->GetBody();
if (bodyA->GetUserData() != NULL && bodyB->GetUserData() != NULL) {
CCSprite *spriteA = (CCSprite *) bodyA->GetUserData();
CCSprite *spriteB = (CCSprite *) bodyB->GetUserData();
if(hasDetectedCollision == NO)
NSLog(@"hasDetectedCollision == NO");
if ((spriteA.tag == 1 && spriteB.tag == 2) || (spriteA.tag == 2 && spriteB.tag == 1)) {
NSLog(@"tag 1 hit tag 2");
}
如果检查 hasDetectedCollision 状态的 if 语句被执行,那么问题不在于 bool 值,而在于碰撞检测。
关于ios - 防止与 b2ContactListener 发生一次碰撞而产生多个回调?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/8275038/