iOS Sprite 套件 : How to make Sprite follow Touches

Question

我是 Sprite Kit 的新手，我想知道如何让 Sprite 跟随触摸。例如，我的玩家 Sprite 位于屏幕底部。当我点击屏幕顶部时，玩家 Sprite 应该以一定的速度移动到触摸点 - 如果我移动手指，它应该始终指向触摸点。这就是我尝试实现它的方式:

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

    for (UITouch *touch in touches) {

        CGPoint location = [touch locationInNode:self];

        CGPoint diff = rwSub(location, self.player.position);
        CGPoint norm = rwNormalize(diff);

        SKAction *act = [SKAction moveByX:norm.x * 10 y:norm.y * 10 duration:0.1];
        [self.player runAction:[SKAction repeatActionForever:act] withKey:@"move"];


    }
}

- (void)touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event {
    for (UITouch *touch in touches) {

        CGPoint location = [touch locationInNode:self];

        CGPoint diff = rwSub(location, self.player.position);
        CGPoint norm = rwNormalize(diff);

        SKAction *act = [SKAction moveByX:norm.x * 10 y:norm.y * 10 duration:0.1];
        [self.player runAction:[SKAction repeatActionForever:act] withKey:@"move"];
    }

}

但是，当移动手指时， Sprite 的移动非常迟缓。有什么办法可以让 Action 变得漂亮流畅吗？

任何帮助将不胜感激!

编辑:我想我已经找到了一个解决方案，我修改了touchesMoved函数:

- (void)touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event
{
    for (UITouch *touch in touches) {

        [self.player removeActionForKey:@"move"];
        CGPoint location = [touch locationInNode:self];

        CGPoint diff = rwSub(location, self.player.position);
        CGPoint norm = rwNormalize(diff);

        [self.player setPosition: rwAdd(self.player.position, rwMult(norm, 2))];
        SKAction *act = [SKAction moveByX:norm.x * 10 y:norm.y * 10 duration:0.01];
        [self.player runAction:[SKAction repeatActionForever:act] withKey:@"move"];
        }
    }

}

Answer 1

我会在 touchesBegan 上将 UITouch 绑定(bind)到 Sprite，在 touchesEnded 上取消绑定(bind)。然后在每次更新时使用单极过滤器接近 UITouch 位置。

根本不需要任何操作，也不需要以这种方式实现 touchesMoved 。整个东西变得更加封装。

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或者使用SKPhysicsJointSpring 。创建一个用于触摸的节点，然后创建一个连接 Sprite 和触摸节点的 Spring 关节。然后仅调整触摸节点位置。

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Sprite

@interface ApproachingSprite : SKSpriteNode
@property (nonatomic, weak) UITouch *touch;
@property (nonatomic) CGPoint targetPosition;
-(void)update;
@end

@implementation ApproachingSprite

-(void)update
{
    // Update target position if any touch bound.
    if (self.touch)
    { self.targetPosition = [self.touch locationInNode:self.scene]; }

    // Approach.
    CGFloat filter = 0.1; // You can fiddle with speed values
    CGFloat inverseFilter = 1.0 - filter;
    self.position = (CGPoint){
        self.targetPosition.x * filter + self.position.x * inverseFilter,
        self.targetPosition.y * filter + self.position.y * inverseFilter,
    };
}

@end

场景

-(void)touchesBegan:(NSSet*)touches withEvent:(UIEvent*) event
{ self.sprite.touch = [touches anyObject]; }

-(void)touchesEnded:(NSSet*)touches withEvent:(UIEvent*) event
{ self.sprite.touch = nil; }

-(void)update:(CFTimeInterval) currentTime
{ [self.sprite update]; }

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