Question

我正在模拟一个蛋形SKSprite节点的物理。但是，有断言失败错误发生：

断言失败：（edge.LengthSquared（）＆gt; 1.19209290e-7F * 1.19209290e-7F），功能设置，文件/SourceCache/PhysicsKit_Sim/PhysicsKit-6.5.4/PhysicsKit/Box2D/Collision/Shapes/b2PolygonShape。 cpp，第180行。

以下是代码：

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];

出了什么问题？任何人都可以帮我解决？非常感谢你！

Answer 1

当你使用＆＃34; bodyWithPolygonFromPath：＆＃34;，你确保路径符合以下条件：

1）。凸多边形路径 2）。逆时针绕组 3）。没有自我交叉点。 //这些点是相对于拥有节点的原点指定的。

您可以在SKPhysicsBody的应用类参考中找到它： https://developer.apple.com/library/ios/documentation/SpriteKit/Reference/SKPhysicsBody_Ref/Reference/Reference.html#//apple_ref/occ/clm/SKPhysicsBody/bodyWithPolygonFromPath：

Answer 2

根据断言，其中一条边比sprite套件预期的最小尺寸短。

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

检查您的路径坐标并确保它不会太小。

Answer 3

在尝试制作三角形路径时，我在较旧的iOS7 iPhone上出现此错误。事实证明，添加最后一行以使路径返回到起点导致错误（尽管较新的iOS版本允许这样做。）IE：

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)

这解释了为什么边缘太小而无法评估 - 两个相同点之间的边缘为0！

使用bodyWithPolygonFromPath：方法进行蛋形时，断言失败

3 个答案: