ios - 如何防止SKSpriteNode的子代与其父代一起旋转？

我使用SpriteKit编写了一个包含大量标记球的iOS游戏。我正在通过构建具有2个 child 的父级SKSpriteNode来构建这些“rollingBalls”:

a)SKShapeNode(实际的圆形)

b)和一个SKLabelNode(标签)

球将在整个屏幕上移动，并与二维物体相互影响，并且完全取决于预期的物理效果(想想台球)。但是，如果可能的话，我希望标签不随父标签一起旋转，以便始终保持可读性。

最简单的方法是什么？

标签不应该是容器的子代吗？还有其他方法可以将其固定到ballShape吗？还是在标签等上可以设置一些属性？

这是我现在得到的:

double ballDiameter = 40;
UIBezierPath* ovalPath = [UIBezierPath bezierPathWithOvalInRect:
                            CGRectMake(-ballDiameter / 2, -ballDiameter / 2,
                                        ballDiameter, ballDiameter)];

SKSpriteNode *container = [[SKSpriteNode alloc]init];

container.name = @"rollingBall";

SKShapeNode *ballShape = [[SKShapeNode alloc] init];
ballShape.path = ovalPath.CGPath;

SKLabelNode *ballLabel = [SKLabelNode labelNodeWithFontNamed:@"Arial"];
ballLabel.text = @"some random string";
ballLabel.horizontalAlignmentMode = SKLabelHorizontalAlignmentModeCenter;
ballLabel.verticalAlignmentMode = SKLabelVerticalAlignmentModeCenter;
ballLabel.position = CGPointMake(0,0);

[container addChild:ballShape];
[container addChild:ballLabel];

container.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:ballDiameter / 2];
container.physicsBody.usesPreciseCollisionDetection = YES;

最佳答案

将所有标签放在单个容器中，将标签添加到关联节点的userData，然后更新标签位置。

// Add a container as a scene instance variable.
SKNode *labels;

- (void)addLabelContainer
{
    labels = [SKNode node];
    [self addChild:labels];
}

- (void)addLabelForNode:(SKNode*)node
{
    SKLabelNode *label = [SKLabelNode labelNodeWithFontNamed:@"Chalkduster"];
    node.userData = [NSMutableDictionary dictionaryWithObject:label forKey:@"label"];
    label.text = node.name;
    label.fontSize = 5;
    label.zPosition = node.zPosition + 1;
    [labels addChild:label];
}

- (void)removeLabelForNode:(SKNode*)node
{
    [[node.userData objectForKey:@"label"] removeFromParent];
    [node.userData removeObjectForKey:@"label"];
}

- (void)update:(NSTimeInterval)currentTime
{
    for (SKNode *node in self.children) {
        SKNode *label = (SKLabelNode*)[node.userData objectForKey:@"label"];
        if (label) {
            label.position = node.position;
        }
    }
}

参见https://github.com/pmark/MartianRover/blob/master/hiSpeed/hiSpeed/Scenes/LimboScene.m