这篇文章主要介绍多段线实现布尔运算的方法
先上代码

function getOperatedCurves(sourceCurs: Curve[], targetCus: Curve[])
    {
        let source: Polyline | Circle = (sourceCurs[0] instanceof Circle) ? sourceCurs[0] as Circle : new Polyline().Combine(sourceCurs)[0];
        let target: Polyline | Circle = (targetCus[0] instanceof Circle) ? targetCus[0] as Circle : new Polyline().Combine(targetCus)[0];
        try
        {
            if (!source.IsClose || !target.IsClose) throw new Error("不是封闭曲线");
        }
        catch (err)
        {
            console.log(err);
        }

        let interPts = source.IntersectWith(target, IntersectOption.OnBothOperands);
        let sourceContainerTarget = isTargetCurInSourceCur(source, target);
        let targetContainerSource = isTargetCurInSourceCur(target, source);

        let isContainer = sourceContainerTarget || targetContainerSource;
        let intersectionList: Curve[] = [];  //交集
        let unionList: Curve[] = []; //并集
        let subList: Curve[] = []; //补集

        /*
        *两封闭区域有交点并且不是包含关系,则通过交点把区域分割
        */
        if (interPts.length && !isContainer)
        {
            let pars1 = interPts.map(p => source.GetParamAtPoint(p)).sort((a, b) => a - b);
            let pars2 = interPts.map(p => target.GetParamAtPoint(p)).sort((a, b) => a - b);

            let cus1: Array<Polyline | Arc> = source.GetSplitCurves(pars1);

            cus1.forEach(pl =>
            {
                if (isTargetCurInSourceCur(target, pl))
                {
                    intersectionList.push(pl);
                }
                else
                {
                    subList.push(pl);
                    unionList.push(pl);
                }
            })

            let cus2: Array<Polyline | Arc> = target.GetSplitCurves(pars2);
            cus2.forEach(pl =>
            {
                if (isTargetCurInSourceCur(source, pl))
                {
                    intersectionList.push(pl);
                    subList.push(pl);
                }
                else
                {
                    unionList.push(pl);
                }
            })

        }
        else
        {
            if (isContainer)
            {
                if (sourceContainerTarget)
                {
                    intersectionList.push(target);
                    subList.push(source, target);
                    unionList.push(source);
                }
                else
                {
                    unionList.push(target);
                    intersectionList.push(source);
                }
            }
            else
            {
                unionList.push(source, target)
                subList.push(source);
            }

        }
        return {
            intersectionList, unionList, subList
        }
    }

由于一些曲线类实现方法不一，这里主要说一些实现布尔运算的思路

• 判断2封闭曲线是否是被包含的关系
• 获取2封闭曲线的所有交点，这里交点可能是圆和线，线和线，圆和圆的，求交点的方法网上应该很多，以后有时间也会写写用JavaScript实现方式
• 根据所有的交点把2封闭曲线分割为多个部分
• 对分割后的线段进行整理，其中相交部分是曲线在对方曲线内部的部分，合并是互不在对方曲线内部的部分，相减类似不想说了，具体看代码，如果是被包含状态则更加就简单了