當使用bodyWithPolygonFromPath時，斷言失敗：蛋形狀的方法

Question

我正在模擬物理到蛋形SKSprite節點。 但是，斷言失敗的錯誤發生：

斷言失敗：（edge.LengthSquared（）> 1.19209290e-7F * 1.19209290e-7F），功能設置，文件/SourceCache/PhysicsKit_Sim/PhysicsKit-6.5。 4/PhysicsKit/Box2D的/碰撞/型材/ b2PolygonShape.cpp，管線180

以下是代碼：

self.egg = [SKSpriteNode spriteNodeWithImageNamed:IMAGE_NAME_EGG]; 
    [self.egg setScale:0.2]; 
    self.egg.position = CGPointMake(self.size.width/2,self.size.height - self.egg.size.height/2); 
    self.egg.name = IMAGE_NAME_EGG; 

    CGPoint startPoint = CGPointMake(0, self.egg.size.height*0.4); 
    CGPoint endPoint = CGPointMake(self.egg.size.width, startPoint.y); 
    CGPoint controlPointLeft = CGPointMake(startPoint.x, self.egg.size.height); 
    CGPoint controlPointRight = CGPointMake(endPoint.x, controlPointLeft.y); 


    CGMutablePathRef pathRef = CGPathCreateMutable();   
    CGPathMoveToPoint(pathRef, NULL, startPoint.x, startPoint.y); 
    CGPathAddQuadCurveToPoint(pathRef, NULL, controlPointLeft.x, controlPointLeft.y, self.egg.size.width/2, controlPointLeft.y); 
    CGPathAddQuadCurveToPoint(pathRef, NULL, controlPointRight.x, controlPointRight.y, endPoint.x,endPoint.y); 
    CGPathAddArc(pathRef, NULL, self.egg.size.width/2, startPoint.y, self.egg.size.width/2, 0, M_PI, NO); 

    self.egg.physicsBody = [SKPhysicsBody bodyWithPolygonFromPath:pathRef]; 
    self.egg.physicsBody.dynamic = YES; 
    self.egg.physicsBody.categoryBitMask = eggCategory; 
    self.egg.physicsBody.contactTestBitMask = rabbitCategory; 
    self.egg.physicsBody.collisionBitMask = rabbitCategory; 
    self.egg.physicsBody.allowsRotation = YES; 
    [self addChild:self.egg]; 

有什麼不對？任何人都可以幫我解決？非常感謝你！

Answer 1

根據該斷言，其中一個邊緣比sprite套件預期的最小尺寸短。

Assertion failed: (edge.LengthSquared() > 1.19209290e-7F * 1.19209290e-7F) 

檢查路徑座標，並確保它不會太小。

當您使用 「bodyWithPolygonFromPath：」

Answer 2

，你MUT確保路徑肉類下列條件：

1）。凸多邊形路徑 2）。逆時針纏繞 3）。沒有自我交集。 //這些點是相對於擁有節點的原點指定的。

你可以找到它在申請SKPhysicsBody這裏類參考： https://developer.apple.com/library/ios/documentation/SpriteKit/Reference/SKPhysicsBody_Ref/Reference/Reference.html#//apple_ref/occ/clm/SKPhysicsBody/bodyWithPolygonFromPath：

Answer 3

我試圖做一個三角形路徑時，對舊的iOS7 iPhone這個錯誤。事實證明，加入最後一行帶來的路徑返回到導致錯誤的起點IE（雖然新版iOS版本允許這樣。）：

CGPathMoveToPoint(path, nil, self.size.width/2, self.size.height/2) 
CGPathAddLineToPoint(path, nil, -self.size.width/2, 0.0) 
CGPathAddLineToPoint(path, nil, self.size.width/2, -self.size.height/2) 
CGPathAddLineToPoint(path, nil, self.size.width/2, self.size.height/2) //REMOVED THIS LINE TO FIX 
CGPathCloseSubpath(path) 

這解釋了爲什麼是太小邊緣評估 - 兩個相同點之間的邊界是0！