修复:避免差集后无法分裂实体 fix #I3FOH0

src/DatabaseServices/Contour.ts

@@ -4,6 +4,7 @@ import { curveLinkGroup, equalCurve } from "../Common/CurveUtils";
 import { Status } from "../Common/Status";
 import { FixIndex } from "../Common/Utils";
 import { IntersectBox2 } from "../Geometry/Box";
+import { CreateContour2 } from "../Geometry/CreateContour2";
 import { Route } from "../Geometry/CurveMap";
 import { equaln, equalv2, equalv3 } from "../Geometry/GeUtils";
 import { RegionParse } from "../Geometry/RegionParse";
@@ -400,7 +401,7 @@ export class Contour
             for (let routes of routeSet)
             {
                 let cs: Curve[] = routes.map(r => r.curve);
-                let c = Contour.CreateContour(cs, false);
+                let c = Contour.CreateContour(cs, false) ?? CreateContour2(cs);
                 if (c
                     && !equalCurve(c.Curve, this.Curve)
                     && targets.every(target => !equalCurve(c.Curve, target.Curve))

src/Geometry/CreateContour2.ts

@@ -1,10 +1,10 @@
 import { Vector3 } from "three";
-import { Polyline } from "../api";
 import { arrayPushArray } from "../Common/ArrayExt";
 import { Contour } from "../DatabaseServices/Contour";
 import { Circle } from "../DatabaseServices/Entity/Circle";
 import { Curve } from "../DatabaseServices/Entity/Curve";
 import { Ellipse } from "../DatabaseServices/Entity/Ellipse";
+import { Polyline } from "../DatabaseServices/Entity/Polyline";
 import { Spline } from "../DatabaseServices/Spline";
 import { IntersectOption } from "../GraphicsSystem/IntersectWith";
 import { CurveIntersection2 } from "./CurveIntersection";