Sprite Kit - 确定滑动手势的矢量以轻弹精灵 [英] Sprite Kit - Determine vector of swipe gesture to flick sprite

问题描述

我有一个游戏，其中圆形物体从屏幕底部弹起，我希望能够滑动它们以朝我滑动的方向轻弹它们.我的问题是，我不知道如何计算滑动的矢量/方向，以便让圆形物体以适当的速度在正确的方向上轻弹.

I have a game where circular objects shoot up from the bottom of the screen and I would like to be able to swipe them to flick them in the direction of my swipe. My issue is, I don't know how to calculate the vector/direction of the swipe in order to get the circular object to get flicked in the proper direction with the proper velocity.

我使用的静态向量(5,5)"需要通过滑动速度和滑动方向来计算.另外，我需要确保一旦我第一次接触到物体，它就不再发生，以免双重撞击物体.这是我目前正在做的事情:

The static vector "(5,5)" I am using needs to be calculated by the swipe speed and direction of the swipe. Also, I need to make sure that once I make first contact with the object, it no longer happens, as to refrain from double hitting the object. Here's what I am doing currently:

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {

for (UITouch *touch in touches) {
    CGPoint location = [touch locationInNode:self];

    SKNode* node = [self nodeAtPoint:location];
    [node.physicsBody applyImpulse:CGVectorMake(5, 5) atPoint:location];
}
}

推荐答案

以下是如何检测滑动手势的示例:

Here's an example of how to detect a swipe gesture:

首先，定义实例变量来存储起始位置和时间.

First, define instance variables to store the starting location and time .

    CGPoint start;
    NSTimeInterval startTime;

在 touchesBegan 中，保存触摸事件的位置/时间.

In touchesBegan, save the location/time of a touch event.

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

    /* Avoid multi-touch gestures (optional) */
    if ([touches count] > 1) {
        return;
    }
    UITouch *touch = [touches anyObject];
    CGPoint location = [touch locationInNode:self];
    // Save start location and time
    start = location;
    startTime = touch.timestamp;
}

定义滑动手势的参数.相应地调整这些.

Define parameters of the swipe gesture. Adjust these accordingly.

#define kMinDistance    25
#define kMinDuration    0.1
#define kMinSpeed       100
#define kMaxSpeed       500

在 touchesEnded 中，通过比较开始和结束位置以及时间戳之间的差异来确定用户的手势是否为滑动.

In touchesEnded, determine if the user's gesture was a swipe by comparing the differences between starting and ending locations and time stamps.

- (void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {

    UITouch *touch = [touches anyObject];
    CGPoint location = [touch locationInNode:self];
    // Determine distance from the starting point
    CGFloat dx = location.x - start.x;
    CGFloat dy = location.y - start.y;
    CGFloat magnitude = sqrt(dx*dx+dy*dy);
    if (magnitude >= kMinDistance) {
        // Determine time difference from start of the gesture
        CGFloat dt = touch.timestamp - startTime;
        if (dt > kMinDuration) {
            // Determine gesture speed in points/sec
            CGFloat speed = magnitude / dt;
            if (speed >= kMinSpeed && speed <= kMaxSpeed) {
                // Calculate normalized direction of the swipe
                dx = dx / magnitude;
                dy = dy / magnitude;
                NSLog(@"Swipe detected with speed = %g and direction (%g, %g)",speed, dx, dy);
            }
        }
    }
}

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