修正当线段丢失的时候,越界访问

__test__/Polyline/offset.test.ts

@@ -379,3 +379,19 @@ test('闭合多段线偏移测试14', () =>
     // expect(cus[0].GetOffsetCurves(1).length).toBe(1);
     // expect(cus[0].GetOffsetCurves(1.2).length).toBe(3);
 })
+
+test('提前丢失所有的线段', () =>
+{
+    let f = new CADFile();
+
+    f.Data =
+        [1, ["Polyline", 1, 1, 12, false, 7, -1, [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, -17.386067452264705, 17.11283965241085, 0, 1], 2, 3, [108.37693694676932, 28.257776463252547], 0.4472440944881872, [108.37693694676932, 17.68555707305448], 3.5940684866260213, [111.70676982557188, 14.089337563947739], 0.5086040192926764, false]];
+
+    f.Read();
+
+    let pl = f.ReadObject() as Polyline;
+
+    let cus = pl.GetOffsetCurves(-7.155086190577401);
+
+    expect(cus.length).toBe(0);
+});

src/GraphicsSystem/OffestPolyline.ts

@@ -224,7 +224,10 @@ export class PolyOffestUtil
         arrayRemoveIf(offResList, r => !r.curve || equaln(r.curve.Length, 0, 1e-6));
 
         if (offResList.length <= 1)
+        {
             this.m_RetCurves = offResList.map(r => r.curve);
+            return;
+        }
 
         //下一线段起始点
         let nextStartPt: Vector3 = offResList[0].curve.StartPoint;