Spritekit 如何根据触摸和按住的位置运行 SKAction

Question

所以我试图在游戏中实现一种方法，如果玩家的手指在 y 轴上的 50 或更低的位置触摸屏幕，SKAction 将运行以将角色精灵向下移动，如果他们的手指触摸到 50 以上，另一个动作将向上移动精灵。我不知道你是如何让它识别触摸并保持的。请帮忙。

Answer 1

您需要捕获用户的触摸事件才能完成此操作。我建议查看 RayWenderlich 提供的优秀教程：Animating Textures and Moving Them With Touch Events

如果您没有时间，您的代码可能如下所示：

首先，您需要了解两个最通用的触摸事件是： -(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event 和： -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event

基本上，当用户将手指放在屏幕上时会调用 touches started 方法，而当用户将手指从屏幕上移开时会触发 touches end 方法。

在本例中，我将使用 touchesEnded，但如果您愿意，可以随意更改它，就像将“Ended”切换为“Began”一样简单。

我即将向您展示的所有代码都将发生在场景实现文件中：

如果您只想让精灵在某个点以上时向上移动，在某个点以下时向下移动，请使用以下命令：

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    //capture the location of the touch
    CGPoint location = [[touches anyObject] locationInNode:self];

    //used to hold the location to travel
    CGPoint moveLocation;

    //check if the Y location is less than 50
    if(location.y < 50)
    {
        //the the location to the bottom of the screen
         moveLocation = CGPointMake(sprite.position.x, 0);
    }
    //and then if its more than 50
    else
    {
        //set the locaiton to the top of the screen
        moveLocation = CGPointMake(sprite.position.x, self.frame.size.height);
    }

    //move the sprite

    //Check if their already moving
    if(sprite actionForKey:@"moving")
    {
        //If they are stop them so they can move in the new direction
        [sprite removeActionForKey:@"moving"];
    }
    SKAction *moveAction = [SKAction moveTo:location duration:5.0f];

    //remember to give the action a key so that we can check for it during the above if statement
    [sprite runAction:moveAction withKey:@"moving"];
}

你有它。唯一的缺陷是，无论您与该位置的距离如何，到达该位置总是需要 5 秒，如果您想要有关如何纠正该问题的提示，或者如果您想了解如何使精灵移动到任何位置，请继续阅读触摸屏幕上的位置。

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    //capture the location of the touch
    CGPoint location = [[touches anyObject] locationInNode:self];

    //move the sprite

    //Check if their already moving
    if(sprite actionForKey:@"moving")
    {
        //If they are stop them so they can move in the new direction
        [sprite removeActionForKey:@"moving"];
    }
    SKAction *moveAction = [SKAction moveTo:location duration:5.0f];

    //remember to give the action a key so that we can check for it during the above if statement
    [sprite runAction:moveAction withKey:@"moving"];
}

该代码将在 5 秒内使精灵移动到屏幕上触摸的位置。请记住用您的 SKSpriteNode 变量的名称替换“sprite”的实例。对于更复杂的运动，请尝试以下操作：

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    //capture the location of the touch
    CGPoint location = [[touches anyObject] locationInNode:self];
    //set the velocity of the subject
    float velocity = self.frame.size.width/3.0;
    //The above will ensure that it will take the sprite 3 seconds to travel the distance of the screen

    //Determine the difference between the point touched and the sprites position
    CGPoint moveDifference = CGPointMake(location.x - sprite.position.x, location.y - sprite.position.y);

    //Use pythagorean theorem to figure out the actual length to move
    float distanceToMove = sqrtf(moveDifference.x * moveDifference.x + moveDifference.y*moveDifference.y);

    //Use the distance to travel and the velocity to determine how long the sprite should move for
    float moveDuration = distanceToMove / velocity;

    //and finally move the sprite
    if(sprite actionForKey:@"moving")
    {
        [sprite removeActionForKey:@"moving"];
    }
    SKAction *moveAction = [SKAction moveTo:location duration:moveDuration];

    [sprite runAction:moveAction withKey:@"moving"];
}

这将为精灵设置一个速度，确定旅行的长度，以及到达新位置需要多长时间。

如果您想涉及纹理，我强烈建议您阅读我提供的链接。

根据要求，我也很乐意提供使用力来控制移动速度的示例。

希望对您有所帮助，如果有任何问题我无法运行代码，请告诉我，但我确信它没问题。