Cocos2d:如何通过捏合实现缩放

Question

Cocos2d:你好.很长一段时间试图通过缩放捏,但并非不可能.你能告诉我们如何实现缩放.

Answer 1

这是我在我的一个游戏中用于缩放缩放的代码.

首先将@property添加到要剪切缩放的场景的@interface(或更可能的图层):

@property (nonatomic, strong) NSMutableSet * touches;

这里是您可以添加到图层的@implementation的代码

- (void) ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    [_touches unionSet:touches];
}

- (void) ccTouchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
    [_touches minusSet:touches];
}

- (void) ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    [_touches minusSet:touches];
}

- (void) ccTouchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    for (UITouch * touch in touches)
    {
        [self pinchZoomWithMovedTouch:touch];
    }
}

- (void) pinchZoomWithMovedTouch: (UITouch *) movedTouch
{
    CGFloat minDistSqr = CGFLOAT_MAX;
    UITouch * nearestTouch = nil;
    UIView * mainView = [[CCDirector sharedDirector] view];
    CGPoint newLocation = [movedTouch locationInView:mainView];
    for (UITouch * touch in _touches)
    {
        if (touch != movedTouch)
        {
            CGFloat distSqr = sqrOfDistanceBetweenPoints([touch locationInView:mainView],newLocation);
            if (distSqr < minDistSqr)
            {
                minDistSqr = distSqr;
                nearestTouch = touch;
            }
        }
    }
    if (nearestTouch)
    {
        CGFloat prevDistSqr = sqrOfDistanceBetweenPoints([nearestTouch locationInView:mainView],
                                                         [movedTouch previousLocationInView:mainView]);
        CGFloat pinchDiff = sqrtf(minDistSqr) - sqrtf(prevDistSqr);
        self.scale += pinchDiff * kPinchZoomCoeff; // kPinchZoomCoeff is constant = 1.0 / 200.0f Adjust it for your needs
    }
}

CGFloat sqrOfDistanceBetweenPoints(CGPoint p1, CGPoint p2)
{
    CGPoint diff = ccpSub(p1, p2);
    return diff.x * diff.x + diff.y * diff.y;
}

请注意,我已经复制了大部分代码,删除了无关的逻辑并且没有启动此代码.如果您对此代码有任何问题,请与我们联系.