Sprite Kit SKPhysicsJoint

Question

我試圖用Sprite Kit的聯合系統進行實驗。到目前爲止，我很難製作一串「串」/「繩」。最終目標是生產一種像籃球網那樣的左邊繩索（垂直），1條右邊繩索（垂直），至少兩條繩索之間連接左邊的&右邊繩索（水平） - 共4條繩索。之後，弄清楚如何使2條水平繩索在穿過它們時不與物體（炮彈？）碰撞。有誰知道如何做這樣的事情？我一直在嘗試這2周，我的眼睛&手指疼痛。

Answer 1

您可以連接幾個物理體與限位接頭一起創建一個像受到與其他物體碰撞影響的結構的繩索。我的代碼非常混亂，但這裏是一個Sprite套件項目的Scene類。它有一個籃球網，當你點擊屏幕時，它會產生一個球。

與截圖這裏https://dl.dropboxusercontent.com/s/flixgbhfk2yysr8/screenshot.jpg?dl=0

編輯：我們對此深感抱歉，代碼現在在OBJ-C

編輯：粘貼這些方法到您的SKScene子類：

-(void)addBasketAtPos:(CGPoint)pos WithSize:(CGSize)size HoopThickness:(CGFloat)hoopThickness RopeThickness:(CGFloat)ropeThickness GapSize:(CGFloat)gapSize { 

    int nSect=ceil(size.height/(ropeThickness*4)); 

    SKSpriteNode *hoop=[SKSpriteNode spriteNodeWithColor:[SKColor redColor] size:CGSizeMake(size.width+hoopThickness, hoopThickness)]; 
    hoop.position=pos; 
    //[self addChild:hoop]; 

    SKNode *lHoopEdge=[SKNode node]; 
    lHoopEdge.position=CGPointMake(pos.x-size.width/2, pos.y); 
    lHoopEdge.physicsBody=[SKPhysicsBody bodyWithCircleOfRadius:hoopThickness/2]; 
    lHoopEdge.physicsBody.dynamic=false; 
    lHoopEdge.physicsBody.restitution=0.9; 
    [self addChild:lHoopEdge]; 
    SKNode *rHoopEdge=[SKNode node]; 
    rHoopEdge.position=CGPointMake(pos.x+size.width/2, pos.y); 
    rHoopEdge.physicsBody=[SKPhysicsBody bodyWithCircleOfRadius:hoopThickness/2]; 
    rHoopEdge.physicsBody.dynamic=false; 
    rHoopEdge.physicsBody.restitution=0.9; 
    [self addChild:rHoopEdge]; 

    NSMutableArray *rope1=[self makeRopeAtPos:lHoopEdge.position node:lHoopEdge num: nSect gap:size.height/nSect width:ropeThickness]; 
    NSMutableArray *rope2=[self makeRopeAtPos:rHoopEdge.position node:lHoopEdge num: nSect gap:size.height/nSect width:ropeThickness]; 

    CGFloat insetStep=(size.width-gapSize)/2/nSect; 
    for (int i=0;i<rope1.count;++i) { 
     SKNode *a=[rope1 objectAtIndex:i]; 
     SKNode *b=[rope2 objectAtIndex:i]; 
     a.position=CGPointMake(a.position.x+i*insetStep, a.position.y); 
     b.position=CGPointMake(b.position.x-i*insetStep, b.position.y); 
    } 

    for (int i=0;i<rope1.count;++i) { 
     /* 
     SKNode *n1=[rope1 objectAtIndex:i]; 
     SKNode *n2=[rope2 objectAtIndex:i]; 
     SKPhysicsJointLimit* joint=[self joinBodyA:n1.physicsBody bodyB:n2.physicsBody ropeThickness:ropeThickness]; 
     [self.physicsWorld addJoint:joint]; 
     */ 
     if (i>0) { 
      [self.physicsWorld addJoint:[self joinBodyA:((SKNode*)[rope1 objectAtIndex:i]).physicsBody 
                bodyB:((SKNode*)[rope2 objectAtIndex:i-1]).physicsBody 
              ropeThickness:ropeThickness]]; 
      [self.physicsWorld addJoint:[self joinBodyA:((SKNode*)[rope2 objectAtIndex:i]).physicsBody 
                bodyB:((SKNode*)[rope1 objectAtIndex:i-1]).physicsBody 
              ropeThickness:ropeThickness]]; 
     } 
     if (i==rope1.count-1) { 
      [self.physicsWorld addJoint:[self joinBodyA:((SKNode*)[rope1 objectAtIndex:i]).physicsBody 
                bodyB:((SKNode*)[rope2 objectAtIndex:i]).physicsBody 
              ropeThickness:ropeThickness]]; 
     } 
    } 

    [self addChild:hoop]; 
} 

-(NSMutableArray*)makeRopeAtPos:(CGPoint)p node:(SKNode*)node num:(int)num gap:(CGFloat)gap width:(CGFloat)width { 
    NSMutableArray *array=[[NSMutableArray alloc] init]; 
    SKNode *last=node; 
    CGPoint pos=p; 
    CGPoint anchor=pos; 
    for (int i=0; i<num; ++i) { 
     pos=CGPointMake(pos.x, pos.y-gap); 
     last=[self makeRopeSegAtPos:pos prev:last anchor:anchor first:(i==0) width:width]; 
     anchor=pos; 
     [array addObject:last]; 
    } 
    return array; 
} 

-(SKNode*)makeRopeSegAtPos:(CGPoint)pos prev:(SKNode*)prev anchor:(CGPoint)anchor first:(BOOL)first width:(CGFloat)width { 
    //SKNode *r=[SKNode node]; 
    SKSpriteNode *r=[SKSpriteNode spriteNodeWithColor:[SKColor whiteColor] size:CGSizeMake(anchor.y-pos.y, width)]; 
    r.position=pos; 
    r.anchorPoint=CGPointMake(0, 0.5); 
    if (first) { 
     //r.size=CGSizeMake(10, 20); 
     r.constraints=@[[SKConstraint orientToPoint:anchor inNode:self offset:nil]]; 
    }else { 
     r.constraints=@[[SKConstraint orientToNode:prev offset:nil]]; 
    } 
    r.physicsBody=[SKPhysicsBody bodyWithCircleOfRadius:width]; 
    r.physicsBody.allowsRotation=NO; 
    //r.physicsBody.density=0.2; 
    r.physicsBody.linearDamping=0.8; 
    [self addChild:r]; 
    SKPhysicsJointLimit *j=[SKPhysicsJointLimit jointWithBodyA:r.physicsBody bodyB:prev.physicsBody anchorA:r.position anchorB:anchor]; 
    [self.physicsWorld addJoint:j]; 
    return r; 

} 

-(SKPhysicsJoint*)joinBodyA:(SKPhysicsBody*)bodyA bodyB:(SKPhysicsBody*)bodyB ropeThickness:(CGFloat)ropeThickness { 
SKPhysicsJointLimit *j=[SKPhysicsJointLimit jointWithBodyA:bodyA bodyB:bodyB anchorA:bodyA.node.position anchorB:bodyB.node.position]; 
SKSpriteNode *rope=[SKSpriteNode spriteNodeWithColor:[SKColor whiteColor] size:CGSizeMake(j.maxLength, ropeThickness)]; 

rope.anchorPoint=CGPointMake(0, 0.5); 
rope.constraints=@[[SKConstraint distance:[SKRange rangeWithUpperLimit:1] toNode:bodyA.node],[SKConstraint orientToNode:bodyB.node offset:nil]]; 
SKAction *keepLength=[SKAction repeatActionForever:[SKAction sequence:@[[SKAction waitForDuration:1/60],[SKAction runBlock:^{ 
    rope.size=CGSizeMake(sqrtf(powf(bodyA.node.position.x-bodyB.node.position.x, 2)+powf(bodyA.node.position.y-bodyB.node.position.y, 2)), rope.size.height); 
}]]]]; 
[rope runAction:keepLength]; 
[self addChild:rope]; 
return j; 

}

使用

[self addBasketAtPos: CGPointMake(self.size.width/2, self.size.height*0.7) 
      WithSize: CGSizeMake(100, 100) 
     HoopThickness: 10 
     RopeThickness: 5 
      GapSize: 80 
]; 

添加一個籃子

在這裏看到新的截圖：https://dl.dropboxusercontent.com/s/xe07ri70rgpxp47/screenshot%202.jpg?dl=0