typescript 八叉树的简单实现

interface QuadTreeNode<T> {
    bounds: {
        x: number,
        y: number,
        width: number,
        height: number
    };
    nodes: QuadTreeNode<T>[];
    items: T[];
    split(): void;
    insert(item: T, x: number, y: number): void;
    retrieve(x: number, y: number): T[];
}
 
class QuadTree<T> implements QuadTreeNode<T> {
    bounds: { x: number, y: number, width: number, height: number };
    nodes: QuadTreeNode<T>[];
    items: T[];
    maxItems: number;
    maxDepth: number;
 
    constructor(x: number, y: number, width: number, height: number, maxItems: number, maxDepth: number) {
        this.bounds = { x, y, width, height };
        this.items = [];
        this.nodes = [];
        this.maxItems = maxItems;
        this.maxDepth = maxDepth;
    }
 
    split(): void {
        if (this.nodes.length > 0) {
            return; // already split
        }
        const { x, y, width, height } = this.bounds;
        const nextWidth = width / 2;
        const nextHeight = height / 2;
        this.nodes = [
            new QuadTree(x, y, nextWidth, nextHeight, this.maxItems, this.maxDepth - 1),
            new QuadTree(x + nextWidth, y, nextWidth, nextHeight, this.maxItems, this.maxDepth - 1),
            new QuadTree(x, y + nextHeight, nextWidth, nextHeight, this.maxItems, this.maxDepth - 1),
            new QuadTree(x + nextWidth, y + nextHeight, nextWidth, nextHeight, this.maxItems, this.maxDepth - 1)
        ];
    }
 
    insert(item: T, x: number, y: number): void {
        if (this.nodes.length > 0 && this.bounds.width / 2 > 0 && this.bounds.height / 2 > 0) {
            const index = this.getIndex(x, y);
            if (index !== -1) {
                this.nodes[index].insert(item, x, y);
                return;
            }
        }
        this.items.push(item);
        if (this.items.length > this.maxItems && this.bounds.width / 2 > 0 && this.bounds.height / 2 > 0 && this.maxDepth > 0) {
            if (this.nodes.length === 0) {
                this.split();
            }
            while (this.items.length > 0) {
                const item = this.items.pop();
                const index = this.getIndex(x, y);