Question

我正在将二进制空间分区上的this ActionScript tutorial转换为Swift，以便可以在类似流氓的游戏中使用它。我遇到了麻烦。

在文章中，作者按如下方式初始化其类：

public function Leaf(X:int, Y:int, Width:int, Height:int)
{
    // initialize our leaf
    x = X;
    y = Y;
    width = Width;
    height = Height;
}

当我将其翻译成Swift时，我遇到了一个错误。上面的代码并未初始化其所有声明的值。这导致我陷入无法解决的错误。不知何故，本文的作者使用此函数在初始化范围之外初始化了leftChild和rightChild变量。

public function split():Boolean
{
    // begin splitting the leaf into two children
    if (leftChild != null || rightChild != null)
        return false; // we're already split! Abort!

    // determine direction of split
    // if the width is >25% larger than height, we split vertically
    // if the height is >25% larger than the width, we split horizontally
    // otherwise we split randomly
    var splitH:Boolean = FlxG.random() > 0.5;
    if (width > height && width / height >= 1.25)
        splitH = false;
    else if (height > width && height / width >= 1.25)
        splitH = true;

    var max:int = (splitH ? height : width) - MIN_LEAF_SIZE; // determine the maximum height or width
    if (max <= MIN_LEAF_SIZE)
        return false; // the area is too small to split any more...

    var split:int = Registry.randomNumber(MIN_LEAF_SIZE, max); // determine where we're going to split

    // create our left and right children based on the direction of the split
    if (splitH)
    {
        leftChild = new Leaf(x, y, width, split);
        rightChild = new Leaf(x, y + split, width, height - split);
    }
    else
    {
        leftChild = new Leaf(x, y, split, height);
        rightChild = new Leaf(x + split, y, width - split, height);
    }
    return true; // split successful!
}

在ActionScript中可以使用哪种方式，但是在Swift中，这会导致我遇到问题。

这是我的翻译代码（Swift）：

private let mapWidth:Int = 50
private let mapHeight:Int = 50

class Leaf {
    var leftLeaf = [Leaf]()
    var rightLeaf = [Leaf]()

    var minLeafSize:Int = 6
    var x, y, width, height: Int

    var leftChild:Leaf
    var rightChild:Leaf

    init (X:Int, Y:Int, W:Int, H:Int) {

        x = Y
        y = Y

        width = W
        height = H

        let maxLeafSize:UInt = 20

        var leaves = [Leaf]()

        // first, create a Leaf to be the 'root' of all Leafs.
        let root = Leaf(X: 0, Y: 0, W: mapWidth, H: mapHeight)
        leaves.append(root)

        var didSplit:Bool = true
        // we loop through every Leaf in our Vector over and over again, until no more Leafs can be split.
        while (didSplit) {
            didSplit = false
            for l in leaves {
                if l.leftLeaf.isEmpty == true && l.rightLeaf.isEmpty == true {
                    // if this Leaf is too big, or 75% chance...
                    if l.width > maxLeafSize || l.height > maxLeafSize || Int(arc4random_uniform(100)) > 25 {
                        if (l.split()) {
                            // if we did split, push the child leafs to the Vector so we can loop into them next
                            leaves.append(l.leftChild)
                            leaves.append(l.rightChild)
                            didSplit = true
                        }
                    }
                }
            }
        }
    }
    func split() -> Bool {
        if leftLeaf.isEmpty == true || rightLeaf.isEmpty == true {
            return false
        }

        var splitH = arc4random_uniform(100) > 50 ? true : false

        if width > height && Double(width / height) >= 1.25 {
            splitH = false
        }
        if height > width && Double(height / width) >= 1.25 {
            splitH = true
        }

        let max:Int = (splitH ? height : width) - minLeafSize // determine the maximum height or width
        if max <= minLeafSize { return false }

        let split:Int = Int(arc4random_uniform(UInt32(minLeafSize - max) + UInt32(max)))

        if (splitH) {
            leftChild = Leaf(X: x, Y: y, W: width, H: split)
            rightChild = Leaf(X: x, Y: y + split, W: width, H: height - split)

            leftLeaf.append(leftChild)
            rightLeaf.append(rightChild)
        } else {
            leftChild = Leaf(X: x, Y: y, W: split, H: height)
            rightChild = Leaf(X: x + split, Y: y, W: width - split, H: height);

            leftLeaf.append(leftChild)
            rightLeaf.append(rightChild)
        }
        return true
    }
}

（据我所知）它与本文中的ActionScript代码相同。但这给我一个错误。 leftChild和rightChild变量未在我的init方法中初始化。当我将split() -> Bool函数移到init方法中时，它不会让我使用该函数，给我一个错误“ Leaf类型的值没有成员split（）”。从l行中删除if (l.spit())给了我第二个错误“声明前使用局部变量'split'”。 split()函数必须在初始化范围之外。

如果我尝试像这样初始化leftChild和rightChild：

init (X:Int, Y:Int, W:Int, H:Int) {

    x = Y
    y = Y

    width = W
    height = H

    leftChild = Leaf(X: x, Y: y, W: width, H: height)
    rightChild = Leaf(X: x, Y: y, W: width, H: height)
}

它创建一个无限循环，最终导致崩溃。

代码应该在leftChild函数中初始化rightChild和split() -> Bool，但是我不认为这就是Swift中的工作方式。您应该能够将其复制/粘贴到Swift文件中，并得到相同的错误。

为什么会这样？我的代码写得不好吗？我该如何解决？

Answer 1

在ActionScript中，将使用特殊值undefined自动评估未初始化的变量；此外，在ActionScript中，undefined == null也是如此，这就是if (leftChild != null || rightChild != null)起作用的原因。

在Swift中，您需要显式allow变量为零。您担心的变量需要以nil开始（如果允许，它们会自动将它们的类型设置为Optional-注意问号）：

var leftChild:Leaf?
var rightChild:Leaf?

BSP Dungeon Generator产生无法修复的错误

1 个答案: