Question

的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

以下是我在其中一款游戏中用于缩放缩放的代码。

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

@property (nonatomic, strong) NSMutableSet * touches;

以下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，我已删除大部分代码并删除了无关的逻辑，并且无法启动此代码。如果您对此代码有任何问题，请与我们联系。

Answer 2

因为我在Javascript中寻找它很久现在尝试实现它，

var listener = cc.EventListener.create({
        event: cc.EventListener.TOUCH_ALL_AT_ONCE,
        swallowTouches: true,
        kPinchZoomCoeff: 1 / 200,
        _touches: {},
        thresHold: [],
        onTouchesBegan: function (touches, event) {
            for (var i = 0; i < touches.length; i++) {
                var touch = touches[i];
                this._touches[touch.getID()] = touch.getLocationInView();
            }
        },
        onTouchesCancelled: function (touches, event) {
            for (var i = 0; i < touches.length; i++) {
                var touch = touches[i];
                delete this._touches[touch.getID()];
            }
        },
        onTouchesEnded: function (touches, event) {
            for (var i = 0; i < touches.length; i++) {
                var touch = touches[i];
                delete this._touches[touch.getID()];
            }
        },
        onTouchesMoved: function (touches, event) {
            for (var i = 0; i < touches.length; i++) {
                var touch = touches[i];
                this.pinchZoomWithMovedTouch(touch, event);
            }
        },
        pinchZoomWithMovedTouch: function (movedTouch, event) {
            var minDistSqr = 300000;
            var nearestTouch = null;
            var target = event.getCurrentTarget();
            var newLocation = movedTouch.getLocationInView();
            for (var i in this._touches) {
                var location = this._touches[i];
                if (i != movedTouch.getID()) {
                    var distSqr = this.sqrOfDistanceBetweenPoints(location, newLocation);
                    this.thresHold.push(distSqr);
                    if (distSqr < minDistSqr) {
                        minDistSqr = distSqr;
                        nearestTouch = location;
                    }
                }
            }
            if (nearestTouch) {
                var prevDistSqr = this.sqrOfDistanceBetweenPoints(nearestTouch, movedTouch.getPreviousLocationInView());
                var pinchDiff = Math.sqrt(minDistSqr) - Math.sqrt(prevDistSqr);
                cc.log(pinchDiff);
                target.scale += pinchDiff * this.kPinchZoomCoeff;
            }
        },
        sqrOfDistanceBetweenPoints: function (p1, p2) {
            return Math.pow(p1.x - p2.x, 2) + Math.pow(p1.y - p2.y, 2);
        }
    });
    cc.eventManager.addListener(listener, this);

Answer 3

这似乎是similar to this post。我在那里给了一个（希望完整的）答案。请看一下。

Cocos2d：如何通过捏合实现缩放

3 个答案: