ios - SpriteKit 接头

Question

我正在尝试制作一个动画角色，可以在不移动他的躯干的情况下伸手去拿屏幕上的东西。

如果他够不到，他的手应该朝这个方向移动最大量，然后被他的静态躯干的物理限制所抵消。



所以在我的代码中，绿色矩形( hand )在我点击的地方移动，躯干随之移动。
我希望能够使红色矩形( 主体 )静止，并使绿色矩形“点”在触摸点位置。

我试图在场景和红体矩形之间应用一个固定的关节，但这似乎不起作用。

- (void) createSceneContent
{
    SKSpriteNode *body = [SKSpriteNode spriteNodeWithColor:[SKColor redColor] size:CGSizeMake(100, 100)];
    body.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame));
    [self addChild:body];

    body.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:body.size];
    body.physicsBody.affectedByGravity = NO;
    body.physicsBody.dynamic = YES;

    self.hand = [SKSpriteNode spriteNodeWithColor:[SKColor greenColor] size:CGSizeMake(150, 20)];
    self.hand.position = CGPointMake(body.position.x + body.size.width / 2 + self.hand.size.width / 2, body.position.y);
    [self addChild:self.hand];
    self.hand.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:self.hand.size];
    self.hand.physicsBody.dynamic = NO;

    self.scene.physicsBody = [SKPhysicsBody bodyWithEdgeLoopFromRect:self.frame];

    [self.physicsWorld addJoint:[SKPhysicsJointPin jointWithBodyA:body.physicsBody bodyB:self.hand.physicsBody anchor:CGPointMake(body.position.x + body.size.width / 2, body.position.y)]];

    [self.hand runAction:[SKAction moveByX:100 y:10 duration:0.1]];
}

- (void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [touches anyObject];

    CGPoint location = [touch locationInNode:self];
    [self.hand runAction:[SKAction moveTo:location duration:0.1]];
}

Answer 1

首先，如果您只希望 ARM 指向触摸的位置，您实际上并不需要在这里使用物理。
只需更改 arm 节点的 anchorPoint到肩部(将销钉放在关节上的位置)并围绕该点旋转它(该点保存在辅助肩部节点中，以便稍后转换为它的坐标)。您可以使用 atan2f 计算旋转角度.这是代码:

- (void) createSceneContent
{
    SKSpriteNode *body = [SKSpriteNode spriteNodeWithColor:[SKColor redColor] size:CGSizeMake(100, 100)];
    body.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame));
    [self addChild:body];

    self.hand = [SKSpriteNode spriteNodeWithColor:[SKColor greenColor] size:CGSizeMake(150, 20)];
    self.hand.position = CGPointMake(body.position.x + body.size.width*0.5, body.position.y);
    self.hand.anchorPoint = CGPointMake(0, 0.5);
    [self addChild:self.hand];

    SKNode *shoulderNode = [SKNode node];
    shoulderNode.position = self.hand.position;
    shoulderNode.name = @"shoulderNode";
    [self addChild:shoulderNode];

}

- (void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [touches anyObject];

    CGPoint location = [touch locationInNode:self];
    CGPoint locationConv = [self convertPoint:location toNode:[self childNodeWithName:@"shoulderNode"]];

    self.hand.zRotation = (atan2f(locationConv.y, locationConv.x));
}

另一方面，如果您需要在这里使用物理实体，使用 SKActions 移动 ARM 可能不是一个好主意，您可能还需要设置 body.physicsBody.dynamic = NO使躯干静止。然后，确保正确添加销接头，并将其frictionTorque 属性设置为较高的值以减少悬空。使手点位于正确位置的方法之一是在更新方法中设置它的速度矢量 - 只需使用转换后的位置坐标(这里它们是相对于 body 节点的中心)。完整示例代码:

- (void) createSceneContent {
    self.physicsBody = [SKPhysicsBody bodyWithEdgeLoopFromRect:self.frame];

    body = [SKSpriteNode spriteNodeWithColor:[SKColor redColor] size:CGSizeMake(100, 100)];
    body.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame));
    [self addChild:body];

    body.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:body.size];
    body.physicsBody.dynamic = NO;
    body.physicsBody.affectedByGravity = YES;

    self.hand = [SKSpriteNode spriteNodeWithColor:[SKColor greenColor] size:CGSizeMake(20, 150)];
    // experiment with the anchorPoint for different results
    self.hand.anchorPoint = CGPointMake(0.5, 0);
    self.hand.position = CGPointMake(body.position.x, body.position.y);
    [self addChild:self.hand];

    self.hand.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:self.hand.size];
    self.hand.physicsBody.dynamic = YES;
    self.hand.physicsBody.affectedByGravity = NO;

    SKPhysicsJointPin *pinHand = [SKPhysicsJointPin jointWithBodyA:body.physicsBody bodyB:self.hand.physicsBody anchor:CGPointMake(body.position.x, body.position.y-5)];
    [self.physicsWorld addJoint:pinHand];
    // experiment with the friction torque value to achieve desired results
    pinHand.frictionTorque = 1.0;
}

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

-(void)update:(CFTimeInterval)currentTime {
    CGPoint locationConv = [self convertPoint:location toNode:body];
    // experiment with the multiplier (here: 10) for faster/slower movement
    self.hand.physicsBody.velocity = CGVectorMake(locationConv.x*10, locationConv.y*10);
}

希望有帮助!