Cocos2d / Box2d运动体的奇怪行为

时间:2013-03-16 12:33:25

标签: cocos2d-iphone box2d-iphone

我正在开发一款非常简单的游戏。这是我的敌人类名为Machine的行为代码:

#import "Machine.h"

@implementation Machine

+(id)machineWithWorld:(b2World*)world position:(CGPoint)pos
{
    return [[[self alloc] initWithWorld:world position:pos] autorelease];
}

-(id)initWithWorld:(b2World*)world position:(CGPoint)pos
{
    if(self = [super initWithShape:[AppDelegate renameFrameForIpad:@"machine"] inWorld:world])
    {
        size = [CCDirector sharedDirector].winSize;

        self.body->SetTransform([Helper toMeters:pos], 0.0);
        self.body->SetType(b2_staticBody);

        safetyCounter = 5;
        [self schedule:@selector(machineSafetyCounter)];

        movementWidthInMeters = (size.width-self.contentSize.width)/PTM_RATIO;
        linearSpeed = 0.5;
        [self schedule:@selector(startMoving) interval:1.5];
    }

    return self;
}

#pragma mark<Machine Behavior>

-(void)startMoving
{
    [self unschedule:_cmd];

    float distanceFromCenterInMeters = (size.width/2 - self.position.x)/PTM_RATIO;
    float interval = ABS(distanceFromCenterInMeters/linearSpeed);
    if(interval < 0.01f)
        interval = 0.02f;

    b2Vec2 motionDirection = (distanceFromCenterInMeters > 0.0f) ? b2Vec2(1.0, 0.0) : b2Vec2(-1.0, 0.0);
    self.body->SetType(b2_kinematicBody);
    self.body->SetLinearVelocity(linearSpeed*motionDirection);

    [self schedule:@selector(startMotionFromBeginning) interval:interval-0.01];

    CCLOG(@"startMoving distance-->%f, interval-->%f", distanceFromCenterInMeters, interval);
}

-(void)startMotionFromBeginning
{
    [self unschedule:_cmd];

    float interval = (movementWidthInMeters/2)/linearSpeed;

    self.body->SetLinearVelocity(0.5*b2Vec2(1.0, 0.0));
    [self schedule:@selector(moveRTL) interval:interval-0.01];

    [self schedule:@selector(checkIfHelmetIsBelowMachine) interval:0.1];

    CCLOG(@"startMotionFromBeginning interval-->%f", interval);
}

-(void)moveRTL
{
    [self unschedule:_cmd];

    float interval = movementWidthInMeters/linearSpeed;

    self.body->SetLinearVelocity(0.5*b2Vec2(-1.0, 0.0));
    [self schedule:@selector(moveLTR) interval:interval-0.01];

    CCLOG(@"moveRTL interval-->%f", interval);
}

-(void)moveLTR
{
    [self unschedule:_cmd];

    float interval = movementWidthInMeters/linearSpeed;

    self.body->SetLinearVelocity(0.5*b2Vec2(1.0, 0.0));
    [self schedule:@selector(moveRTL) interval:interval-0.01];

    CCLOG(@"moveLTR interval-->%f", interval);
}

-(void)checkIfHelmetIsBelowMachine
{
    [self unschedule:_cmd];

    Helmet* helmet = (Helmet*)[[[[[CCDirector sharedDirector] runningScene] children] objectAtIndex:0] getChildByTag:kTagHelmet];
    float helmetPosX = helmet.position.x;

    if((self.position.x > helmetPosX) && (self.position.x < helmetPosX+helmet.contentSize.width))
    {
        [self unscheduleAllSelectors];
        [self schedule:@selector(machineSafetyCounter) interval:0.1];

        [self schedule:@selector(startMovingDownwards) interval:0.0];

        return;
    }

    [self schedule:_cmd interval:0.1];
}

-(void)startMovingDownwards
{
    [self unschedule:_cmd];

    self.body->SetLinearVelocity(0.25*b2Vec2(0.0, -1.0));
    [self schedule:@selector(stopMovingDownwards) interval:1.0];

    CCLOG(@"startMovingDownwards");
}

-(void)stopMovingDownwards
{
    [self unschedule:_cmd];

    self.body->SetLinearVelocity(b2Vec2(0.0, 0.0));
    [self schedule:@selector(startMoving) interval:0.2];

    CCLOG(@"stopMovingDownwards");
}

我所做的就是:

1)身体最初是静态的,位于ccp(size.width * 0.5,size.height * 0.75)。

2)1.5秒后,它变为运动学并开始以0.5米/秒的线速度移动。

3)它检查当前距离(从屏幕宽度中心保持高度相同),评估到达该点所需的时间,然后开始沿水平方向移动。

4)到达那个地点后,它开始它的签名动作,它开始从左向右移动,如果在任何时候头盔(另一个游戏对象)经过它下面,它开始向下移动并在1.0秒后停止,然后整个循环重复。

5)它移动LTR&amp; RTL,直到它找到下面的头盔时开始向下移动。

现在的问题是,有时行为与预期完全相同。 很多次,它开始向上移动,我从未在正方向上设置运动矢量的y位。

1 个答案:

答案 0 :(得分:0)

初始化身体后,你不应该改变它的bodyType.当你第一次制作身体时,将它设置为运动学,这样你以后在尝试改变时就不会遇到问题。身体是否附着在CCSprite上?如果是这样,您应该将该类设为CCSprite的子类,以便您可以使用
[super initWithFile:(NSString *) world:(b2World *)]或您选择的某种方法来促进您的努力。