Spritekit场景锚点影响子节点定位

Posted 2023-03-14

【中文标题】Spritekit场景锚点影响子节点定位

【英文标题】：Spritekit scene anchorpoint affecting child node positioning

【发布时间】：2014-01-09 09:57:50

【问题描述】：

我创建了我的 SKScene 子类，它设置锚点，然后为世界添加一个 SKSpriteNode，世界有多个 SKSpriteNodes 用于障碍物、玩家等。我也以

为中心

我遇到的问题是，当我将场景的锚点设置为 (0.5, 0.5) 时，我添加到世界的任何子节点的位置都从世界的中心开始。如何修复节点的位置，使 position = (0,0) 位于世界节点的左下角，并添加任何子节点，而不是中心？

@implementation LevelScene

-(id)initWithSize:(CGSize)size 
if (self = [super initWithSize:size]) 

    NSLog(@"width:%f height:%f", self.view.bounds.size.width, self.view.bounds.size.height);


    // set the physics body
    self.physicsWorld.gravity = CGVectorMake(0,-5);
    self.physicsWorld.contactDelegate = self;
    self.anchorPoint = CGPointMake(0.5, 0.5);

    NSMutableDictionary *plistDict = [[NSMutableDictionary alloc] initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"LevelScene" ofType:@"plist"]];
    NSString *backgroundImage = [plistDict objectForKey:@"background"];

    // add a node that holds the background
    background = [SKSpriteNode spriteNodeWithTexture:[SKTexture textureWithImageNamed:backgroundImage] size:CGSizeMake(1024, 768)];
    background.position = CGPointMake(0, 0);
    [self addChild:background];

    world = [SKSpriteNode spriteNodeWithColor:[SKColor brownColor] size:CGSizeMake(1024, 768)];
    world.position = CGPointMake(0, 0); // this should be bottom-left
    world.size = CGSizeMake(1024, 768);
    world.physicsBody = [SKPhysicsBody bodyWithEdgeLoopFromRect:world.frame];
    world.physicsBody.categoryBitMask = worldCategory;
    [self addChild:world];

    // load in the game tiles (these are non-dynamic tiles the player can use)
    [self loadInTiles];

    // add in game object to the world skspritenode - this just creates a subclass of skspritenode and sets position to 0,0
    [self addGameObject:CGPointMake(0, 0)];

...


// ...setup functions, input handling, etc

-(void)didSimulatePhysics 

    // setup the player to move depending on their direction
    [player updatePosition];

    [self centreOnNode:player];


-(void)centreOnNode: (SKSpriteNode *)node 
    CGPoint cameraPositionInScene = [node.scene convertPoint:node.position fromNode:node.parent];

    CGFloat x = node.parent.position.x - cameraPositionInScene.x;
    CGFloat y = node.parent.position.y - cameraPositionInScene.y;
    NSLog(@"camera x:%f y:%f", x, y);

    NSLog(@"world frame origin x:%f y:%f", world.frame.origin.x, world.frame.origin.y);

    node.parent.position = CGPointMake(x, y);

【参考方案1】：

如果要将世界精灵的原点设置在左下方，只需设置它的锚点即可。

world.anchorPoint = CGPointMake(0,0);

这样，世界精灵的坐标系将与场景的默认坐标系一样。

确保删除该行：

self.anchorPoint = CGPointMake(0.5, 0.5);

【参考方案2】：

替换这一行：

world.position = CGPointMake(0, 0);

通过这个：

world.position = CGPointMake(-CGRectGetMidX(self.frame), -CGRectGetMidY(self.frame));

(0,0) 是场景的中心，因为您将SKScene 的锚点设置为 (0.5,0.5)

【讨论】：

这似乎不会影响世界 skspritenode 中节点的定位 - 请参阅 dropbox.com/s/grqx20o1lc461m7/…> - 目前游戏对象的位置设置为 0,0 但默认为中心

通过替换：[self addGameObject:CGPointMake(0, 0)];与： CGFloat theX = [playerX floatValue] - CGRectGetMaxX(self.frame); CGFloat theY = [playerY floatValue] - CGRectGetMaxY(self.frame); [self addGameObject:CGPointMake(theX, theY)];这似乎可行，虽然我还需要调整精灵的大小