在Xcode Spritekit中扩展物理实体

Question

我最近遇到了一个问题，我会增加一个节点的大小，但是物理主体的大小会保持不变。我试图找到解决方案但没有成功。如何根据节点的大小调整人体尺寸？

CGPoint location = CGPointMake(randX, -self.frame.size.height - expander.size.height);

SKAction *moveAction = [SKAction moveTo:location duration:randDuration];

SKAction *expandAction = [SKAction resizeToWidth:(expander.size.width * 1.4) height:(expander.size.width * 1.4) duration:1.0];

SKAction *collapseAction = [SKAction resizeToWidth:(expander.size.width) height: (expander.size.height) duration:1.0];

SKAction *doneAction = [SKAction runBlock:(dispatch_block_t)^() {
    expander.hidden = YES;
}];

SKAction *expandCollapseAction = [SKAction repeatActionForever:[SKAction sequence:@[expandAction, collapseAction]]];

SKAction *moveExpandAction = [SKAction group:@[moveAction, expandCollapseAction]];

SKAction *moveExpanderActionWithDone = [SKAction sequence: @[moveExpandAction, doneAction ]];
[expander runAction:moveExpanderActionWithDone withKey: @"expanderMoving"];

Answer 1

我认为这不会起作用，但看起来物理机构毕竟是缩放的。这是可以在iOS8上重现物理体缩放的代码：

- (void)didMoveToView:(SKView *)view {
  /* Setup your scene here */

    SKSpriteNode *s = [SKSpriteNode spriteNodeWithColor:[SKColor yellowColor] size:CGSizeMake(100,100)];
    s.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMinY(self.frame)+100);
    s.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:s.size];

    s.physicsBody.dynamic = YES;

    s.physicsBody.affectedByGravity = NO;

    [self addChild:s];

    [s runAction:[SKAction scaleTo:0.3f duration:5]];

    [s.physicsBody applyImpulse:CGVectorMake(0,30)];

}

如果我没记错的话，这在早些时候没有用过，但我只是试了一下它看起来很有效。尽管如此，这还没有经过全面测试，我不确定这是否会破坏物理模拟。接触检测可能会起作用。我只是想表明，当精灵缩放时，实际的物理实体会被缩放。结果如下：

从上面的gif可以看出，物理体与精灵一起被缩放（没有重新创建另一个不同大小的物理体）。精灵周围的蓝色边界框是精灵物理体的直观表示（在视图控制器中启用skView.showsPhysics = YES）;

Answer 2

这很奇怪，你可以在将它添加到SKNode或SKScene之前添加物理体。例如。

SKTexture  *texture=[_gameTexture textureNamed:@"mysprite"];
SKSpriteNode *bubble=[SKSpriteNode spriteNodeWithTexture:texture];
bubble.anchorPoint=CGPointMake(0.5,0.5);
//_bubble.name=[@"bubble" stringByAppendingFormat:@"%d ",index];
bubble.name=newcolor;

// _bubble.userInteractionEnabled = YES;    _bubble.position = CGPointMake（newPosition.x，newPosition.y）;

//
bubble.physicsBody=[SKPhysicsBody bodyWithCircleOfRadius:60];
bubble.physicsBody.dynamic=NO;
bubble.physicsBody.linearDamping=0;
bubble.physicsBody.restitution=0;


bubble.physicsBody.density=1;
bubble.physicsBody.allowsRotation=NO;
bubble.physicsBody.affectedByGravity=NO;
//_bubble.physicsBody.velocity=CGVectorMake([self getRandomNumberBetween:-10 to:7], [self getRandomNumberBetween:-10 to:7]);
//  _bubble.physicsBody.usesPreciseCollisionDetection=YES;


bubble.physicsBody.categoryBitMask=ballCategory;
bubble.physicsBody.collisionBitMask=ballCategory | pathCategory ;
bubble.physicsBody.contactTestBitMask=ballCategory | pathCategory ;

[self addChild:_bubble];


bubble.xScale=_bubble.yScale=2;
bubble.alpha=0.5;