ios - Spritekit 平行滚动

Question

我的游戏中有一个对象的平行滚动问题，我的对象是一条应该重复的线，但我的代码将该线滚动到屏幕外，然后返回到第一个位置并再次滚动:

 - (void)bricksEdgeAnimation {

    SKSpriteNode *bEdge = [[SKSpriteNode alloc]initWithImageNamed:@"edge.png"];
    bEdge.position = self.view.center;
    bEdge.name = @"edge";
    [self addChild:bEdge];


}

- (void)moveBg
{
    [self enumerateChildNodesWithName:@"edge" usingBlock: ^(SKNode *node, BOOL *stop)
     {
         SKSpriteNode * bg = (SKSpriteNode *) node;
         bg.position = CGPointMake(bg.position.x , bg.position.y - SPEED);

         if (bg.position.y <= -bg.size.width)
         {
             bg.position = CGPointMake(bg.position.x ,
                                       bg.position.y + bg.size.width*2);
         }
     }];
}

-(void)update:(CFTimeInterval)currentTime {

    if (_lastUpdateTime)
    {
        _dt = currentTime - _lastUpdateTime;
    }
    else
    {
        _dt = 0;
    }

    _lastUpdateTime = currentTime;

    [self moveBg];

}

应该是这样的:

应该如何更改我的代码以在彼此之后重复这一行？

Answer 1

添加第二个“边缘”节点:

- (void)bricksEdgeAnimation {

    SKSpriteNode *bEdge = [[SKSpriteNode alloc]initWithImageNamed:@"edge.png"];
    bEdge.position = self.view.center;
    bEdge.name = @"edge";
    [self addChild:bEdge];

    //2nd node - note the name is the same
    SKSpriteNode *bEdge1 = [[SKSpriteNode alloc]initWithImageNamed:@"edge.png"];
    bEdge1.position = CGPointMake(bEdge.position.x,bEdge.position.y+(bEdge.size.height));
    bEdge1.name = @"edge";
    [self addChild:bEdge1];
}

//note I changed "width" to "height"
- (void)moveBg
{
    [self enumerateChildNodesWithName:@"edge" usingBlock: ^(SKNode *node, BOOL *stop)
     {
         SKSpriteNode * bg = (SKSpriteNode *) node;
         bg.position = CGPointMake(bg.position.x , bg.position.y - SPEED);

         if (bg.position.y <= -bg.size.width)
         {
             bg.position = CGPointMake(bg.position.x ,
                                       bg.position.y + bg.size.height*2);
         }
     }];
}